[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (RFC 2518) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 RFC 4918

WebDAV                                                      L. Dusseault
Internet-Draft                                                      OSAF
Obsoletes: 2518 (if approved)                          December 30, 2005
Expires: July 3, 2006


           HTTP Extensions for Distributed Authoring - WebDAV
                    draft-ietf-webdav-rfc2518bis-10

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on July 3, 2006.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   WebDAV consists of a set of methods, headers, and content-types
   ancillary to HTTP/1.1 for the management of resource properties,
   creation and management of resource collections, URL namespace
   manipulation, and resource locking (collision avoidance).

   RFC2518 was published in February 1999, and this specification makes
   minor revisions mostly due to interoperability experience.




Dusseault                 Expires July 3, 2006                  [Page 1]

Internet-Draft                   WebDAV                    December 2005


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   7
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   9
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .  10
   4.  Data Model for Resource Properties  . . . . . . . . . . . . .  11
     4.1.   The Resource Property Model  . . . . . . . . . . . . . .  11
     4.2.   Properties and HTTP Headers  . . . . . . . . . . . . . .  11
     4.3.   XML Usage  . . . . . . . . . . . . . . . . . . . . . . .  11
     4.4.   Property Values  . . . . . . . . . . . . . . . . . . . .  12
       4.4.1.   Example - Property with Mixed Content  . . . . . . .  14
     4.5.   Property Names . . . . . . . . . . . . . . . . . . . . .  15
     4.6.   Source Resources and Output Resources  . . . . . . . . .  16
   5.  Collections of Web Resources  . . . . . . . . . . . . . . . .  17
     5.1.   HTTP URL Namespace Model . . . . . . . . . . . . . . . .  17
     5.2.   Collection Resources . . . . . . . . . . . . . . . . . .  17
   6.  Locking . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
     6.1.   Exclusive Vs. Shared Locks . . . . . . . . . . . . . . .  19
     6.2.   Required Support . . . . . . . . . . . . . . . . . . . .  20
     6.3.   Lock Tokens  . . . . . . . . . . . . . . . . . . . . . .  20
     6.4.   Lock Capability Discovery  . . . . . . . . . . . . . . .  21
     6.5.   Active Lock Discovery  . . . . . . . . . . . . . . . . .  21
     6.6.   Locks and Multiple Bindings  . . . . . . . . . . . . . .  22
   7.  Write Lock  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     7.1.   Lock Owner . . . . . . . . . . . . . . . . . . . . . . .  23
     7.2.   Methods Restricted by Write Locks  . . . . . . . . . . .  23
     7.3.   Write Locks and Lock Tokens  . . . . . . . . . . . . . .  24
     7.4.   Write Locks and Properties . . . . . . . . . . . . . . .  24
     7.5.   Avoiding Lost Updates  . . . . . . . . . . . . . . . . .  24
     7.6.   Write Locks and Unmapped URLs  . . . . . . . . . . . . .  25
     7.7.   Write Locks and Collections  . . . . . . . . . . . . . .  27
     7.8.   Write Locks and the If Request Header  . . . . . . . . .  29
       7.8.1.   Example - Write Lock . . . . . . . . . . . . . . . .  29
     7.9.   Write Locks and COPY/MOVE  . . . . . . . . . . . . . . .  30
     7.10.  Refreshing Write Locks . . . . . . . . . . . . . . . . .  30
   8.  HTTP Methods for Distributed Authoring  . . . . . . . . . . .  31
     8.1.   General Request and Response Handling  . . . . . . . . .  31
       8.1.1.   Use of XML . . . . . . . . . . . . . . . . . . . . .  31
       8.1.2.   Required Bodies in Requests  . . . . . . . . . . . .  31
       8.1.3.   HTTP Headers for use in WebDAV . . . . . . . . . . .  31
       8.1.4.   ETag . . . . . . . . . . . . . . . . . . . . . . . .  31
       8.1.5.   Including error response bodies  . . . . . . . . . .  32
     8.2.   PROPFIND . . . . . . . . . . . . . . . . . . . . . . . .  32
       8.2.1.   PROPFIND status codes  . . . . . . . . . . . . . . .  34
       8.2.2.   Status codes for use with 207 (Multi-Status) . . . .  34
       8.2.3.   Example - Retrieving Named Properties  . . . . . . .  35
       8.2.4.   Example - Retrieving Named and Dead Properties . . .  37
       8.2.5.   Example - Using 'propname' to Retrieve all



Dusseault                 Expires July 3, 2006                  [Page 2]

Internet-Draft                   WebDAV                    December 2005


                Property Names . . . . . . . . . . . . . . . . . . .  37
       8.2.6.   Example - Using 'allprop'  . . . . . . . . . . . . .  39
     8.3.   PROPPATCH  . . . . . . . . . . . . . . . . . . . . . . .  41
       8.3.1.   Status Codes for use in 207 (Multi-Status) . . . . .  42
       8.3.2.   Example - PROPPATCH  . . . . . . . . . . . . . . . .  43
     8.4.   MKCOL Method . . . . . . . . . . . . . . . . . . . . . .  44
       8.4.1.   MKCOL Status Codes . . . . . . . . . . . . . . . . .  45
       8.4.2.   Example - MKCOL  . . . . . . . . . . . . . . . . . .  45
     8.5.   GET, HEAD for Collections  . . . . . . . . . . . . . . .  46
     8.6.   POST for Collections . . . . . . . . . . . . . . . . . .  46
     8.7.   DELETE . . . . . . . . . . . . . . . . . . . . . . . . .  46
       8.7.1.   DELETE for Collections . . . . . . . . . . . . . . .  47
       8.7.2.   Example - DELETE . . . . . . . . . . . . . . . . . .  47
     8.8.   PUT  . . . . . . . . . . . . . . . . . . . . . . . . . .  48
       8.8.1.   PUT for Non-Collection Resources . . . . . . . . . .  48
       8.8.2.   PUT for Collections  . . . . . . . . . . . . . . . .  48
     8.9.   COPY . . . . . . . . . . . . . . . . . . . . . . . . . .  49
       8.9.1.   COPY for Non-collection Resources  . . . . . . . . .  49
       8.9.2.   COPY for Properties  . . . . . . . . . . . . . . . .  49
       8.9.3.   COPY for Collections . . . . . . . . . . . . . . . .  50
       8.9.4.   COPY and Overwriting Destination Resources . . . . .  51
       8.9.5.   Status Codes . . . . . . . . . . . . . . . . . . . .  51
       8.9.6.   Example - COPY with Overwrite  . . . . . . . . . . .  52
       8.9.7.   Example - COPY with No Overwrite . . . . . . . . . .  53
       8.9.8.   Example - COPY of a Collection . . . . . . . . . . .  53
     8.10.  MOVE . . . . . . . . . . . . . . . . . . . . . . . . . .  54
       8.10.1.  MOVE for Properties  . . . . . . . . . . . . . . . .  55
       8.10.2.  MOVE for Collections . . . . . . . . . . . . . . . .  55
       8.10.3.  MOVE and the Overwrite Header  . . . . . . . . . . .  56
       8.10.4.  Status Codes . . . . . . . . . . . . . . . . . . . .  56
       8.10.5.  Example - MOVE of a Non-Collection . . . . . . . . .  57
       8.10.6.  Example - MOVE of a Collection . . . . . . . . . . .  58
     8.11.  LOCK Method  . . . . . . . . . . . . . . . . . . . . . .  58
       8.11.1.  Refreshing Locks . . . . . . . . . . . . . . . . . .  59
       8.11.2.  Depth and Locking  . . . . . . . . . . . . . . . . .  60
       8.11.3.  Locking Unmapped URLs  . . . . . . . . . . . . . . .  60
       8.11.4.  Lock Compatibility Table . . . . . . . . . . . . . .  60
       8.11.5.  LOCK Responses . . . . . . . . . . . . . . . . . . .  61
       8.11.6.  Example - Simple Lock Request  . . . . . . . . . . .  62
       8.11.7.  Example - Refreshing a Write Lock  . . . . . . . . .  64
       8.11.8.  Example - Multi-Resource Lock Request  . . . . . . .  65
     8.12.  UNLOCK Method  . . . . . . . . . . . . . . . . . . . . .  66
       8.12.1.  Status Codes . . . . . . . . . . . . . . . . . . . .  66
       8.12.2.  Example - UNLOCK . . . . . . . . . . . . . . . . . .  67
   9.  HTTP Headers for Distributed Authoring  . . . . . . . . . . .  68
     9.1.   DAV Header . . . . . . . . . . . . . . . . . . . . . . .  68
     9.2.   Depth Header . . . . . . . . . . . . . . . . . . . . . .  68
     9.3.   Destination Header . . . . . . . . . . . . . . . . . . .  70



Dusseault                 Expires July 3, 2006                  [Page 3]

Internet-Draft                   WebDAV                    December 2005


     9.4.   If Header  . . . . . . . . . . . . . . . . . . . . . . .  70
       9.4.1.   No-tag-list Production . . . . . . . . . . . . . . .  71
       9.4.2.   Tagged-list Production . . . . . . . . . . . . . . .  71
       9.4.3.   Example - Tagged List If header in COPY  . . . . . .  72
       9.4.4.   Not Production . . . . . . . . . . . . . . . . . . .  72
       9.4.5.   Matching Function  . . . . . . . . . . . . . . . . .  73
       9.4.6.   If Header and Non-DAV Aware Proxies  . . . . . . . .  73
     9.5.   Lock-Token Header  . . . . . . . . . . . . . . . . . . .  74
     9.6.   Overwrite Header . . . . . . . . . . . . . . . . . . . .  74
     9.7.   Timeout Request Header . . . . . . . . . . . . . . . . .  74
   10. Status Code Extensions to HTTP/1.1  . . . . . . . . . . . . .  76
     10.1.  207 Multi-Status . . . . . . . . . . . . . . . . . . . .  76
     10.2.  422 Unprocessable Entity . . . . . . . . . . . . . . . .  76
     10.3.  423 Locked . . . . . . . . . . . . . . . . . . . . . . .  76
     10.4.  424 Failed Dependency  . . . . . . . . . . . . . . . . .  76
     10.5.  507 Insufficient Storage . . . . . . . . . . . . . . . .  76
   11. Use of HTTP Status Codes  . . . . . . . . . . . . . . . . . .  77
     11.1.  412 Precondition Failed  . . . . . . . . . . . . . . . .  77
     11.2.  414 Request-URI Too Long . . . . . . . . . . . . . . . .  77
   12. Multi-Status Response . . . . . . . . . . . . . . . . . . . .  78
     12.1.  Response headers . . . . . . . . . . . . . . . . . . . .  78
     12.2.  URL Handling . . . . . . . . . . . . . . . . . . . . . .  78
     12.3.  Handling redirected child resources  . . . . . . . . . .  79
     12.4.  Internal Status Codes  . . . . . . . . . . . . . . . . .  79
   13. XML Element Definitions . . . . . . . . . . . . . . . . . . .  80
     13.1.  activelock XML Element . . . . . . . . . . . . . . . . .  80
     13.2.  allprop XML Element  . . . . . . . . . . . . . . . . . .  80
     13.3.  collection XML Element . . . . . . . . . . . . . . . . .  80
     13.4.  dead-props XML Element . . . . . . . . . . . . . . . . .  81
     13.5.  depth XML Element  . . . . . . . . . . . . . . . . . . .  81
     13.6.  error XML Element  . . . . . . . . . . . . . . . . . . .  81
     13.7.  exclusive XML Element  . . . . . . . . . . . . . . . . .  82
     13.8.  href XML Element . . . . . . . . . . . . . . . . . . . .  82
     13.9.  location XML Element . . . . . . . . . . . . . . . . . .  82
     13.10. lockentry XML Element  . . . . . . . . . . . . . . . . .  83
     13.11. lockinfo XML Element . . . . . . . . . . . . . . . . . .  83
     13.12. lockroot XML Element . . . . . . . . . . . . . . . . . .  83
     13.13. lockscope XML Element  . . . . . . . . . . . . . . . . .  84
     13.14. locktoken XML Element  . . . . . . . . . . . . . . . . .  84
     13.15. locktype XML Element . . . . . . . . . . . . . . . . . .  84
     13.16. multistatus XML Element  . . . . . . . . . . . . . . . .  85
     13.17. owner XML Element  . . . . . . . . . . . . . . . . . . .  85
     13.18. prop XML element . . . . . . . . . . . . . . . . . . . .  85
     13.19. propertyupdate XML element . . . . . . . . . . . . . . .  86
     13.20. propfind XML Element . . . . . . . . . . . . . . . . . .  86
     13.21. propname XML Element . . . . . . . . . . . . . . . . . .  86
     13.22. propstat XML Element . . . . . . . . . . . . . . . . . .  87
     13.23. remove XML element . . . . . . . . . . . . . . . . . . .  87



Dusseault                 Expires July 3, 2006                  [Page 4]

Internet-Draft                   WebDAV                    December 2005


     13.24. response XML Element . . . . . . . . . . . . . . . . . .  87
     13.25. responsedescription XML Element  . . . . . . . . . . . .  88
     13.26. set XML element  . . . . . . . . . . . . . . . . . . . .  88
     13.27. shared XML Element . . . . . . . . . . . . . . . . . . .  89
     13.28. status XML Element . . . . . . . . . . . . . . . . . . .  89
     13.29. timeout XML Element  . . . . . . . . . . . . . . . . . .  89
     13.30. write XML Element  . . . . . . . . . . . . . . . . . . .  90
   14. DAV Properties  . . . . . . . . . . . . . . . . . . . . . . .  91
     14.1.  creationdate Property  . . . . . . . . . . . . . . . . .  91
     14.2.  displayname Property . . . . . . . . . . . . . . . . . .  92
     14.3.  getcontentlanguage Property  . . . . . . . . . . . . . .  92
     14.4.  getcontentlength Property  . . . . . . . . . . . . . . .  93
     14.5.  getcontenttype Property  . . . . . . . . . . . . . . . .  94
     14.6.  getetag Property . . . . . . . . . . . . . . . . . . . .  94
     14.7.  getlastmodified Property . . . . . . . . . . . . . . . .  95
     14.8.  lockdiscovery Property . . . . . . . . . . . . . . . . .  95
       14.8.1.  Example - Retrieving the lockdiscovery Property  . .  96
     14.9.  resourcetype Property  . . . . . . . . . . . . . . . . .  97
     14.10. supportedlock Property . . . . . . . . . . . . . . . . .  98
       14.10.1. Example - Retrieving the DAV:supportedlock
                Property . . . . . . . . . . . . . . . . . . . . . .  99
   15. Precondition/postcondition XML elements . . . . . . . . . . . 100
     15.1.  Example - Response with precondition code  . . . . . . . 101
   16. Instructions for Processing XML in DAV  . . . . . . . . . . . 103
   17. DAV Compliance Classes  . . . . . . . . . . . . . . . . . . . 104
     17.1.  Class 1  . . . . . . . . . . . . . . . . . . . . . . . . 104
     17.2.  Class 2  . . . . . . . . . . . . . . . . . . . . . . . . 104
     17.3.  Class 'bis'  . . . . . . . . . . . . . . . . . . . . . . 104
   18. Internationalization Considerations . . . . . . . . . . . . . 105
   19. Security Considerations . . . . . . . . . . . . . . . . . . . 107
     19.1.  Authentication of Clients  . . . . . . . . . . . . . . . 107
     19.2.  Denial of Service  . . . . . . . . . . . . . . . . . . . 107
     19.3.  Security through Obscurity . . . . . . . . . . . . . . . 108
     19.4.  Privacy Issues Connected to Locks  . . . . . . . . . . . 108
     19.5.  Privacy Issues Connected to Properties . . . . . . . . . 108
     19.6.  Implications of XML Entities . . . . . . . . . . . . . . 109
     19.7.  Risks Connected with Lock Tokens . . . . . . . . . . . . 110
     19.8.  Hosting malicious scripts executed on client machines  . 110
   20. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 112
   21. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . 113
     21.1.  Previous Authors' Addresses  . . . . . . . . . . . . . . 114
   22. References  . . . . . . . . . . . . . . . . . . . . . . . . . 115
     22.1.  Normative References . . . . . . . . . . . . . . . . . . 115
     22.2.  Informational References . . . . . . . . . . . . . . . . 115
   Appendix A.  Notes on Processing XML Elements . . . . . . . . . . 117
     A.1.   Notes on Empty XML Elements  . . . . . . . . . . . . . . 117
     A.2.   Notes on Illegal XML Processing  . . . . . . . . . . . . 117
     A.3.   Example - XML Syntax Error . . . . . . . . . . . . . . . 117



Dusseault                 Expires July 3, 2006                  [Page 5]

Internet-Draft                   WebDAV                    December 2005


     A.4.   Example - Unknown XML Element  . . . . . . . . . . . . . 118
   Appendix B.  Notes on HTTP Client Compatibility . . . . . . . . . 119
   Appendix C.  The opaquelocktoken scheme and URIs  . . . . . . . . 120
   Appendix D.  Guidance for Clients Desiring to Authenticate  . . . 121
   Appendix E.  Summary of changes from RFC2518  . . . . . . . . . . 123
     E.1.   Changes Notable to Server Implementors . . . . . . . . . 123
     E.2.   Changes Notable to Client Implementors . . . . . . . . . 124
   Appendix F.  Change Log (to be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . . 126
     F.1.   Changes from -05 to -06  . . . . . . . . . . . . . . . . 126
     F.2.   Changes in -07 . . . . . . . . . . . . . . . . . . . . . 126
     F.3.   Changes in -08 . . . . . . . . . . . . . . . . . . . . . 127
     F.4.   Changes in -09 . . . . . . . . . . . . . . . . . . . . . 128
     F.5.   Chandles in -10  . . . . . . . . . . . . . . . . . . . . 129
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . 130
   Intellectual Property and Copyright Statements  . . . . . . . . . 131



































Dusseault                 Expires July 3, 2006                  [Page 6]

Internet-Draft                   WebDAV                    December 2005


1.  Introduction

   This document describes an extension to the HTTP/1.1 protocol that
   allows clients to perform remote web content authoring operations.
   This extension provides a coherent set of methods, headers, request
   entity body formats, and response entity body formats that provide
   operations for:

   Properties: The ability to create, remove, and query information
   about Web pages, such as their authors, creation dates, etc.  Also,
   the ability to link pages of any media type to related pages.

   Collections: The ability to create sets of documents and to retrieve
   a hierarchical membership listing (like a directory listing in a file
   system).

   Locking: The ability to keep more than one person from working on a
   document at the same time.  This prevents the "lost update problem",
   in which modifications are lost as first one author then another
   writes changes without merging the other author's changes.

   Namespace Operations: The ability to instruct the server to copy and
   move Web resources, operations which change the URL.

   Requirements and rationale for these operations are described in a
   companion document, "Requirements for a Distributed Authoring and
   Versioning Protocol for the World Wide Web" [RFC2291].

   This standard does not specify the versioning operations suggested by
   [RFC2291].  That work was done in a separate document, "Versioning
   Extensions to WebDAV" [RFC3253].

   The sections below provide a detailed introduction to various WebDAV
   abstractions: resource properties (Section 4), collections of
   resources (Section 5), locks (Section 6) in general and write locks
   (Section 7) specifically.

   These abstractions are manipulated by the WebDAV-specific HTTP
   methods (Section 8) and the new HTTP headers (Section 9) used with
   WebDAV methods.

   While the status codes provided by HTTP/1.1 are sufficient to
   describe most error conditions encountered by WebDAV methods, there
   are some errors that do not fall neatly into the existing categories.
   This specification defines new status codes developed for WebDAV
   methods (Section 10) and describes existing HTTP status codes
   (Section 11) as used in WebDAV.  Since some WebDAV methods may
   operate over many resources, the Multi-Status response (Section 12)



Dusseault                 Expires July 3, 2006                  [Page 7]

Internet-Draft                   WebDAV                    December 2005


   has been introduced to return status information for multiple
   resources.  Finally, this version of WebDAV introduces precondition
   and postcondition (Section 15) XML elements in error response bodies.

   WebDAV uses [XML] for property names and some values, and also uses
   XML to marshal complicated request and response.  This specification
   contains DTD and text definitions of all all properties (Section 14)
   and all other XML elements (Section 13) used in marshalling.  WebDAV
   includes a few special rules on how to process XML (Section 16)
   appearing in WebDAV so that it truly is extensible.

   Finishing off the specification are sections on what it means for a
   resource to be compliant with this specification (Section 17), on
   internationalization support (Section 18), and on security
   (Section 19).




































Dusseault                 Expires July 3, 2006                  [Page 8]

Internet-Draft                   WebDAV                    December 2005


2.  Notational Conventions

   Since this document describes a set of extensions to the HTTP/1.1
   protocol, the augmented BNF used herein to describe protocol elements
   is exactly the same as described in section 2.1 of [RFC2616],
   including the rules about implied linear white-space.  Since this
   augmented BNF uses the basic production rules provided in section 2.2
   of [RFC2616], these rules apply to this document as well.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   Note that in natural language, a property like the "creationdate"
   property in the "DAV:" XML namespace is sometimes referred to as
   "DAV:creationdate" for brevity.



































Dusseault                 Expires July 3, 2006                  [Page 9]

Internet-Draft                   WebDAV                    December 2005


3.  Terminology

   URI/URL - A Uniform Resource Identifier and Uniform Resource Locator,
   respectively.  These terms (and the distinction between them) are
   defined in [RFC3986].

   URI/URL Mapping - A relation between an absolute URI and a resource.
   Since a resource can represent items that are not network
   retrievable, as well as those that are, it is possible for a resource
   to have zero, one, or many URI mappings.  Mapping a resource to an
   "http" scheme URI makes it possible to submit HTTP protocol requests
   to the resource using the URI.

   Collection - A resource that contains a set of URLs, which identify
   and locate member resources and which meet the collections
   requirements (Section 5).

   Member URL - A URL which is a member of the set of URLs contained by
   a collection.

   Internal Member URL - A Member URL that is immediately relative to
   the URL of the collection (the definition of immediately relative is
   given later (Section 5.2)).

   Property - A name/value pair that contains descriptive information
   about a resource.

   Live Property - A property whose semantics and syntax are enforced by
   the server.  For example, the live property DAV:getcontentlength has
   its value, the length of the entity returned by a GET request,
   automatically calculated by the server.

   Dead Property - A property whose semantics and syntax are not
   enforced by the server.  The server only records the value of a dead
   property; the client is responsible for maintaining the consistency
   of the syntax and semantics of a dead property.

   Principal - A "principal" is a distinct human or computational actor
   that initiates access to network resources.












Dusseault                 Expires July 3, 2006                 [Page 10]

Internet-Draft                   WebDAV                    December 2005


4.  Data Model for Resource Properties

4.1.  The Resource Property Model

   Properties are pieces of data that describe the state of a resource.
   Properties are data about data.

   Properties are used in distributed authoring environments to provide
   for efficient discovery and management of resources.  For example, a
   'subject' property might allow for the indexing of all resources by
   their subject, and an 'author' property might allow for the discovery
   of what authors have written which documents.

   The DAV property model consists of name/value pairs.  The name of a
   property identifies the property's syntax and semantics, and provides
   an address by which to refer to its syntax and semantics.

   There are two categories of properties: "live" and "dead".  A live
   property has its syntax and semantics enforced by the server.  Live
   properties include cases where a) the value of a property is read-
   only, maintained by the server, and b) the value of the property is
   maintained by the client, but the server performs syntax checking on
   submitted values.  All instances of a given live property MUST comply
   with the definition associated with that property name.  A dead
   property has its syntax and semantics enforced by the client; the
   server merely records the value of the property verbatim.

4.2.  Properties and HTTP Headers

   Properties already exist, in a limited sense, in HTTP message
   headers.  However, in distributed authoring environments a relatively
   large number of properties are needed to describe the state of a
   resource, and setting/returning them all through HTTP headers is
   inefficient.  Thus a mechanism is needed which allows a principal to
   identify a set of properties in which the principal is interested and
   to set or retrieve just those properties.

4.3.  XML Usage

   In HTTP/1.1, method parameter information was exclusively encoded in
   HTTP headers.  Unlike HTTP/1.1, WebDAV encodes method parameter
   information either in an [XML] request entity body, or in an HTTP
   header.  The use of XML to encode method parameters was motivated by
   the ability to add extra XML elements to existing structures,
   providing extensibility; and by XML's ability to encode information
   in ISO 10646 character sets, providing internationalization support.

   In addition to encoding method parameters, XML is used in WebDAV to



Dusseault                 Expires July 3, 2006                 [Page 11]

Internet-Draft                   WebDAV                    December 2005


   encode the responses from methods, providing the extensibility and
   internationalization advantages of XML for method output, as well as
   input.

   When XML is used for a request or response body, the MIME type SHOULD
   be application/xml.  Implementations MUST accept both text/xml and
   application/xml in request and response bodies.  Use of text/xml is
   deprecated.

   The XML namespace extension [W3C.REC-xml-names-19990114] is also used
   in this specification in order to allow for new XML elements to be
   added without fear of colliding with other element names.  Although
   WebDAV request and response bodies can be extended by arbitrary XML
   elements, which can be ignored by the message recipient, an XML
   element in the "DAV:" namespace SHOULD NOT be used in the request or
   response body unless that XML element is explicitly defined in an
   IETF RFC reviewed by a WebDAV working group.

   Note that "DAV:" uses a scheme name defined solely for the purpose of
   creating this XML namespace.  Defining new URI schemes for namespaces
   is discouraged.  "DAV:" was defined before standard best practices
   emerged, and this namespace is still used only because of significant
   existing deployments.

4.4.  Property Values

   The value of a property is always a (well-formed) XML fragment.

   XML has been chosen because it is a flexible, self-describing,
   structured data format that supports rich schema definitions, and
   because of its support for multiple character sets.  XML's self-
   describing nature allows any property's value to be extended by
   adding new elements.  Older clients will not break when they
   encounter extensions because they will still have the data specified
   in the original schema and MUST ignore elements they do not
   understand.

   XML's support for multiple character sets allows any human-readable
   property to be encoded and read in a character set familiar to the
   user.  XML's support for multiple human languages, using the "xml:
   lang" attribute, handles cases where the same character set is
   employed by multiple human languages.  Note that xml:lang scope is
   recursive, so a xml:lang attribute on any element containing a
   property name element applies to the property value unless it has
   been overridden by a more locally scoped attribute.  Note that a
   property only has one value, in one language (or language MAY be left
   undefined), not multiple values in different languages or a single
   value in multiple languages.



Dusseault                 Expires July 3, 2006                 [Page 12]

Internet-Draft                   WebDAV                    December 2005


   A property is always represented in XML with an XML element
   consisting of the property name, called the "property name element".
   The simplest example is an empty property, which is different from a
   property that does not exist:

      <R:title xmlns:R="http://www.example.com/ns/"></R:title>

   The value of a property appears inside the property name element.
   The value may be any kind of well-formed XML content, including both
   text-only and mixed content.  In the latter case, servers MUST
   preserve certain aspects of the content (described using the
   terminology from [W3C.REC-xml-infoset-20040204]).

   For the property name Element Information Item itself:

      [namespace name]

      [local name]

      [attributes] named "xml:lang" or any such attribute in scope

      [children] of type element or character

   On all Element Information Items in the value:

      [namespace name]

      [local name]

      [attributes]

      [children] of type element or character

   On Attribute Information Items in the value:

      [namespace name]

      [local name]

      [normalized value]

   On Character Information Items in the value:

      [character code]

   Since prefixes are used in some XML query/handling tools, servers
   SHOULD preserve, for any Information Item in the value:




Dusseault                 Expires July 3, 2006                 [Page 13]

Internet-Draft                   WebDAV                    December 2005


      [prefix]

   In dead properties (considered as content, like document bodies)
   servers are encouraged to (MAY) preserve, for any Comment Information
   Item in the value:

      [content]

   XML Infoset attributes not listed above MAY be preserved by the
   server, but clients MUST NOT rely on them being preserved.

   The XML attribute xml:space MUST NOT be used to change white space
   handling.  White space in property values is significant.

4.4.1.  Example - Property with Mixed Content

   Consider a dead property 'author' created by the client as follows:

     <D:prop xml:lang="en">
       <x:author xmlns:x='http://example.com/ns'>
         <x:name>Jane Doe</x:name>
         <!-- Jane's contact info -->
         <x:uri type='email'
                added='2005-11-26'>mailto:jane.doe@example.com</x:uri>
         <x:uri type='web'
                added='2005-11-27'>http://www.example.com</x:uri>
         <x:notes xmlns:h='http://www.w3.org/1999/xhtml'>
           Jane has been working way <h:em>too</h:em> long on the
           long-awaited revision of <![CDATA[<RFC2518>]]>.
         </x:notes>
       </x:author>
     </D:prop>

   When this property is requested, a server might return:

     <D:prop><author xmlns:x='http://example.com/ns' xml:lang="en"
             xmlns='http://example.com/ns'
             xmlns:ns1='http://www.w3.org/1999/xhtml'>
         <x:name>Jane Doe</name>
         <x:uri   added="2005-11-26" type="email"
           >mailto:jane.doe@example.com</x:uri>
         <x:uri   added="2005-11-27" type="web"
           >http://www.example.com</x:uri>
         <x:notes>
           Jane has been working way <h:em>too</h:em> long on the
           long-awaited revision of &lt;RFC2518&gt;.
         </x:notes>
       </author>



Dusseault                 Expires July 3, 2006                 [Page 14]

Internet-Draft                   WebDAV                    December 2005


     </D:prop>

   Note in this example:

   o  The [prefix] for the property name itself was not preserved, being
      non-significant

   o  attribute values have been rewritten with double quotes instead of
      single quotes (quoting style is not significant), and attribute
      order has not been preserved,

   o  the xml:lang attribute has been returned on the property name
      element itself (it was in scope when the property was set, but the
      exact position in the response is not considered significant as
      long as it is in scope),

   o  whitespace between tags has been preserved everywhere (whitespace
      between attributes not so),

   o  CDATA encapsulation was replaced with character escaping (the
      reverse would also be legal),

   o  the comment item was stripped (as would have been a processing
      instruction item).

   Implementation note: there are cases such as editing scenarios where
   clients may require that XML content is preserved character-by-
   character (such as attribute ordering or quoting style).  In this
   case, clients should consider using a text-only property value by
   escaping all characters that have a special meaning in XML parsing.

4.5.  Property Names

   A property name is a universally unique identifier that is associated
   with a schema that provides information about the syntax and
   semantics of the property.

   Because a property's name is universally unique, clients can depend
   upon consistent behavior for a particular property across multiple
   resources, on the same and across different servers, so long as that
   property is "live" on the resources in question, and the
   implementation of the live property is faithful to its definition.

   The XML namespace mechanism, which is based on URIs ([RFC3986]), is
   used to name properties because it prevents namespace collisions and
   provides for varying degrees of administrative control.

   The property namespace is flat; that is, no hierarchy of properties



Dusseault                 Expires July 3, 2006                 [Page 15]

Internet-Draft                   WebDAV                    December 2005


   is explicitly recognized.  Thus, if a property A and a property A/B
   exist on a resource, there is no recognition of any relationship
   between the two properties.  It is expected that a separate
   specification will eventually be produced which will address issues
   relating to hierarchical properties.

   Finally, it is not possible to define the same property twice on a
   single resource, as this would cause a collision in the resource's
   property namespace.

4.6.  Source Resources and Output Resources

   Some HTTP resources are dynamically generated by the server.  For
   these resources, there presumably exists source code somewhere
   governing how that resource is generated.  The relationship of source
   files to output HTTP resources may be one to one, one to many, many
   to one or many to many.  There is no mechanism in HTTP to determine
   whether a resource is even dynamic, let alone where its source files
   exist or how to author them.  Although this problem would usefully be
   solved, interoperable WebDAV implementations have been widely
   deployed without actually solving this problem, by dealing only with
   static resources.  Thus, the source vs. output problem is not solved
   in this specification and has been deferred to a separate document.




























Dusseault                 Expires July 3, 2006                 [Page 16]

Internet-Draft                   WebDAV                    December 2005


5.  Collections of Web Resources

   This section provides a description of a new type of Web resource,
   the collection, and discusses its interactions with the HTTP URL
   namespace.  The purpose of a collection resource is to model
   collection-like objects (e.g., file system directories) within a
   server's namespace.

   All DAV compliant resources MUST support the HTTP URL namespace model
   specified herein.

5.1.  HTTP URL Namespace Model

   The HTTP URL namespace is a hierarchical namespace where the
   hierarchy is delimited with the "/" character.

   An HTTP URL namespace is said to be consistent if it meets the
   following conditions: for every URL in the HTTP hierarchy there
   exists a collection that contains that URL as an internal member.
   The root, or top-level collection of the namespace under
   consideration is exempt from the previous rule.  The top-level
   collection of the namespace under consideration is not necessarily
   the collection identified by the absolute path '/', it may be
   identified by one or more path segments (e.g. /servlets/webdav/...)

   Neither HTTP/1.1 nor WebDAV require that the entire HTTP URL
   namespace be consistent -- a WebDAV-compatible resource may not have
   a parent collection.  However, certain WebDAV methods are prohibited
   from producing results that cause namespace inconsistencies.

   Although implicit in [RFC2616] and [RFC3986], any resource, including
   collection resources, MAY be identified by more than one URI.  For
   example, a resource could be identified by multiple HTTP URLs.

5.2.  Collection Resources

   A collection is a resource whose state consists of at least a list of
   internal member URLs and a set of properties, but which may have
   additional state such as entity bodies returned by GET.  An internal
   member URL MUST be immediately relative to a base URL of the
   collection.  That is, the internal member URL is equal to a
   containing collection's URL plus an additional segment for non-
   collection resources, or additional segment plus trailing slash "/"
   for collection resources, where segment is defined in section 3.3 of
   [RFC3986].

   Any given internal member URL MUST only belong to the collection
   once, i.e., it is illegal to have multiple instances of the same URL



Dusseault                 Expires July 3, 2006                 [Page 17]

Internet-Draft                   WebDAV                    December 2005


   in a collection.  Properties defined on collections behave exactly as
   do properties on non-collection resources.

   For all WebDAV compliant resources A and B, identified by URLs U and
   V, for which U is immediately relative to V, B MUST be a collection
   that has U as an internal member URL.  So, if the resource with URL
   http://example.com/bar/blah is WebDAV compliant and if the resource
   with URL http://example.com/bar/ is WebDAV compliant then the
   resource with URL http://example.com/bar/ must be a collection and
   must contain URL http://example.com/bar/blah as an internal member.

   Collection resources MAY list the URLs of non-WebDAV compliant
   children in the HTTP URL namespace hierarchy as internal members but
   are not required to do so.  For example, if the resource with URL
   http://example.com/bar/blah is not WebDAV compliant and the URL
   http://example.com/bar/ identifies a collection then URL
   http://example.com/bar/blah may or may not be an internal member of
   the collection with URL http://example.com/bar/.

   If a WebDAV compliant resource has no WebDAV compliant children in
   the HTTP URL namespace hierarchy then the WebDAV compliant resource
   is not required to be a collection.

   There is a standing convention that when a collection is referred to
   by its name without a trailing slash, the server MAY handle the
   request as if the trailing slash were present.  In this case it
   SHOULD return a Content-Location header in the response, pointing to
   the URL ending with the "/".  For example, if a client invokes a
   method on http://example.com/blah (no trailing slash), the server may
   respond as if the operation were invoked on http://example.com/blah/
   (trailing slash), and should return a Content-Location header with
   the value http://example.com/blah/.  Wherever a server produces a URL
   referring to a collection, the server SHOULD include the trailing
   slash.  In general clients SHOULD use the trailing slash form of
   collection names.  If clients do not use the trailing slash form the
   client needs to be prepared to see a redirect response.  Clients will
   find the DAV:resourcetype property more reliable than the URL to find
   out if a resource is a collection.

   Clients MUST be able to support the case where WebDAV resources are
   contained inside non-WebDAV resources.  For example, if a OPTIONS
   response from "http://example.com/servlet/dav/collection" indicates
   WebDAV support, the client cannot assume that
   "http://example.com/servlet/dav/" or its parent necessarily are
   WebDAV collections.






Dusseault                 Expires July 3, 2006                 [Page 18]

Internet-Draft                   WebDAV                    December 2005


6.  Locking

   The ability to lock a resource provides a mechanism for serializing
   access to that resource.  Using a lock, an authoring client can
   provide a reasonable guarantee that another principal will not modify
   a resource while it is being edited.  In this way, a client can
   prevent the "lost update" problem.

   This specification allows locks to vary over two client-specified
   parameters, the number of principals involved (exclusive vs. shared)
   and the type of access to be granted.  This document defines locking
   for only one access type, write.  However, the syntax is extensible,
   and permits the eventual specification of locking for other access
   types.

6.1.  Exclusive Vs. Shared Locks

   The most basic form of lock is an exclusive lock.  Only one exclusive
   lock may exist on any resource, whether it is directly or indirectly
   locked (Section 7.7).  Exclusive locks avoid having to merge results,
   without requiring any coordination other than the methods described
   in this specification.

   However, there are times when the goal of a lock is not to exclude
   others from exercising an access right but rather to provide a
   mechanism for principals to indicate that they intend to exercise
   their access rights.  Shared locks are provided for this case.  A
   shared lock allows multiple principals to receive a lock.  Hence any
   principal with appropriate access can use the lock.

   With shared locks there are two trust sets that affect a resource.
   The first trust set is created by access permissions.  Principals who
   are trusted, for example, may have permission to write to the
   resource.  Among those who have access permission to write to the
   resource, the set of principals who have taken out a shared lock also
   must trust each other, creating a (typically) smaller trust set
   within the access permission write set.

   Starting with every possible principal on the Internet, in most
   situations the vast majority of these principals will not have write
   access to a given resource.  Of the small number who do have write
   access, some principals may decide to guarantee their edits are free
   from overwrite conflicts by using exclusive write locks.  Others may
   decide they trust their collaborators will not overwrite their work
   (the potential set of collaborators being the set of principals who
   have write permission) and use a shared lock, which informs their
   collaborators that a principal may be working on the resource.




Dusseault                 Expires July 3, 2006                 [Page 19]

Internet-Draft                   WebDAV                    December 2005


   The WebDAV extensions to HTTP do not need to provide all of the
   communications paths necessary for principals to coordinate their
   activities.  When using shared locks, principals may use any out of
   band communication channel to coordinate their work (e.g., face-to-
   face interaction, written notes, post-it notes on the screen,
   telephone conversation, Email, etc.)  The intent of a shared lock is
   to let collaborators know who else may be working on a resource.

   Shared locks are included because experience from web distributed
   authoring systems has indicated that exclusive locks are often too
   rigid.  An exclusive lock is used to enforce a particular editing
   process: take out an exclusive lock, read the resource, perform
   edits, write the resource, release the lock.  This editing process
   has the problem that locks are not always properly released, for
   example when a program crashes, or when a lock owner leaves without
   unlocking a resource.  While both timeouts and administrative action
   can be used to remove an offending lock, neither mechanism may be
   available when needed; the timeout may be long or the administrator
   may not be available.

6.2.  Required Support

   A WebDAV compliant resource is not required to support locking in any
   form.  If the resource does support locking it may choose to support
   any combination of exclusive and shared locks for any access types.

   The reason for this flexibility is that locking policy strikes to the
   very heart of the resource management and versioning systems employed
   by various storage repositories.  These repositories require control
   over what sort of locking will be made available.  For example, some
   repositories only support shared write locks while others only
   provide support for exclusive write locks while yet others use no
   locking at all.  As each system is sufficiently different to merit
   exclusion of certain locking features, this specification leaves
   locking as the sole axis of negotiation within WebDAV.

6.3.  Lock Tokens

   A lock token is a type of state token, represented as a URI, which
   identifies a particular lock.  Each lock has exactly one unique lock
   token generated by the server.  Clients MUST NOT attempt to interpret
   lock tokens in any way.

   Lock token URIs MUST be unique across all resources for all time.
   This uniqueness constraint allows lock tokens to be submitted across
   resources and servers without fear of confusion.  Since lock tokens
   are unique, a client MAY submit a lock token in an If header on a
   resource other than the one that returned it.



Dusseault                 Expires July 3, 2006                 [Page 20]

Internet-Draft                   WebDAV                    December 2005


   When a LOCK operation creates a new lock, the new lock token is
   returned in the Lock-Token response header defined in Section 9.5,
   and also in the body of the response.

   Submitting a lock token does not confer full privilege to use the
   lock token or modify the locked resource.  Write access and other
   privileges MUST be enforced through normal privilege or
   authentication mechanisms, not based on the possible obscurity of
   lock token values.

   Servers MAY make lock tokens publicly readable (e.g. in the DAV:
   lockdiscovery property).  One use case for making lock tokens
   readable is so that a long-lived lock can be removed by the resource
   owner (the client that obtained the lock might have crashed or
   disconnected before cleaning up the lock).  Except for the case of
   using UNLOCK under user guidance, a client SHOULD NOT use a lock
   tokens created by another client instance.

   This specification encourages servers to create UUIDs for lock
   tokens, and to use the URI form defined by "A Universally Unique
   Identifier (UUID) URN Namespace" ([RFC4122]).  However servers are
   free to use any URI (e.g. from another scheme) so long as it meets
   the uniqueness requirements.  For example, a valid lock token might
   be constructed using the "opaquelocktoken" scheme defined in
   Appendix C.

   Example: "urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6"

6.4.  Lock Capability Discovery

   Since server lock support is optional, a client trying to lock a
   resource on a server can either try the lock and hope for the best,
   or perform some form of discovery to determine what lock capabilities
   the server supports.  This is known as lock capability discovery.  A
   client can determine what lock types the server supports by
   retrieving the DAV:supportedlock property.

   Any DAV compliant resource that supports the LOCK method MUST support
   the DAV:supportedlock property.

6.5.  Active Lock Discovery

   If another principal locks a resource that a principal wishes to
   access, it is useful for the second principal to be able to find out
   who the first principal is.  For this purpose the DAV:lockdiscovery
   property is provided.  This property lists all outstanding locks,
   describes their type, and MAY even provide the lock tokens.




Dusseault                 Expires July 3, 2006                 [Page 21]

Internet-Draft                   WebDAV                    December 2005


   Any DAV compliant resource that supports the LOCK method MUST support
   the DAV:lockdiscovery property.

6.6.  Locks and Multiple Bindings

   A resource may be made available through more than one URI.  A lock
   MUST cover the resource as well as the URI to which the LOCK request
   was addressed.  The lock MAY cover other URIs mapped to the same
   resource as well.










































Dusseault                 Expires July 3, 2006                 [Page 22]

Internet-Draft                   WebDAV                    December 2005


7.  Write Lock

   This section describes the semantics specific to the write lock type.
   The write lock is a specific instance of a lock type, and is the only
   lock type described in this specification.

   An exclusive write lock will prevent parallel changes to a resource
   by any principal other than the write lock holder.  In general terms,
   changes affected by write locks include changes to:

   o  the content of the resource

   o  any dead property of the resource

   o  any live property defined to be lockable (all properties defined
      in this specification are lockable)

   o  the direct membership of the resource, if it is a collection

   o  the URL/location of a resource

   The next few sections describe in more specific terms how write locks
   interact with various operations.

7.1.  Lock Owner

   The creator of the lock is the lock owner.  The server MUST restrict
   the usage of the lock token to the lock owner (both for shared and
   exclusive locks -- for multi-user shared lock cases, each
   authenticated principal MUST obtain its own shared lock).

   The server MAY allow privileged users other than the lock owner to
   destroy a lock (for example, the resource owner or an administrator)
   as a special case of lock usage.

   If an anonymous user requests a lock, the server MAY refuse the
   request.

7.2.  Methods Restricted by Write Locks

   A server MUST reject any write request that alters a write-locked
   resource unless a valid lock token is provided.  The write operations
   defined in HTTP and WebDAV are PUT, POST, PROPPATCH, LOCK, UNLOCK,
   MOVE, COPY (for the destination resource), DELETE, and MKCOL.  All
   other HTTP/WebDAV methods, GET in particular, function independently
   of the lock.  A shared write lock prevents the same operations
   (except additional requests for shared write locks), however it also
   allows access by any principal that has a shared write lock on the



Dusseault                 Expires July 3, 2006                 [Page 23]

Internet-Draft                   WebDAV                    December 2005


   same resource.

   Note, however, that as new methods are created it will be necessary
   to specify how they interact with a write lock.

7.3.  Write Locks and Lock Tokens

   A successful request for an exclusive or shared write lock MUST
   result in the generation of a unique lock token associated with the
   requesting principal.  Thus if five principals have a shared write
   lock on the same resource there will be five lock tokens, one for
   each principal.

7.4.  Write Locks and Properties

   While those without a write lock may not alter a property on a
   resource it is still possible for the values of live properties to
   change, even while locked, due to the requirements of their schemas.
   Only dead properties and live properties defined to respect locks are
   guaranteed not to change while write locked.

7.5.  Avoiding Lost Updates

   Although the write locks provide some help in preventing lost
   updates, they cannot guarantee that updates will never be lost.
   Consider the following scenario:

   Two clients A and B are interested in editing the resource
   'index.html'.  Client A is an HTTP client rather than a WebDAV
   client, and so does not know how to perform locking.

   Client A doesn't lock the document, but does a GET and begins
   editing.

   Client B does LOCK, performs a GET and begins editing.

   Client B finishes editing, performs a PUT, then an UNLOCK.

   Client A performs a PUT, overwriting and losing all of B's changes.

   There are several reasons why the WebDAV protocol itself cannot
   prevent this situation.  First, it cannot force all clients to use
   locking because it must be compatible with HTTP clients that do not
   comprehend locking.  Second, it cannot require servers to support
   locking because of the variety of repository implementations, some of
   which rely on reservations and merging rather than on locking.
   Finally, being stateless, it cannot enforce a sequence of operations
   like LOCK / GET / PUT / UNLOCK.



Dusseault                 Expires July 3, 2006                 [Page 24]

Internet-Draft                   WebDAV                    December 2005


   WebDAV servers that support locking can reduce the likelihood that
   clients will accidentally overwrite each other's changes by requiring
   clients to lock resources before modifying them.  Such servers would
   effectively prevent HTTP 1.0 and HTTP 1.1 clients from modifying
   resources.

   WebDAV clients can be good citizens by using a lock / retrieve /
   write /unlock sequence of operations (at least by default) whenever
   they interact with a WebDAV server that supports locking.

   HTTP 1.1 clients can be good citizens, avoiding overwriting other
   clients' changes, by using entity tags in If-Match headers with any
   requests that would modify resources.

   Information managers may attempt to prevent overwrites by
   implementing client-side procedures requiring locking before
   modifying WebDAV resources.

7.6.  Write Locks and Unmapped URLs

   WebDAV provides the ability to lock an unmapped URL in order to
   reserve the name for use.  This is a simple way to avoid the lost-
   update problem on the creation of a new resource (another way is to
   use If-None-Match header specified in HTTP 1.1).  It has the side
   benefit of locking the new resource immediately for use of the
   creator.

   Note that the lost-update problem is not an issue for collections
   because MKCOL can only be used to create a collection, not to
   overwrite an existing collection.  When trying to lock a collection
   upon creation, clients may attempt to increase the likelihood of
   getting the lock by pipelining the MKCOL and LOCK requests together
   (but because this doesn't convert two separate operations into one
   atomic operation there's no guarantee this will work).

   A successful lock request to an unmapped URL MUST result in the
   creation of an locked resource with empty content.  Subsequently, a
   successful PUT request (with the correct lock token) provides the
   content for the resource, and the server MUST also use the content-
   type and content-language information from this request.

   The original WebDAV model for locking unmapped URLs created "lock-
   null resources".  This model was over-complicated and some
   interoperability and implementation problems were discovered.  The
   new WebDAV model for locking unmapped URLs creates "locked empty
   resources".  Servers MUST implement either lock-null resources or
   locked empty resources, but servers SHOULD implement locked empty
   resources.  This section discusses the original model briefly and the



Dusseault                 Expires July 3, 2006                 [Page 25]

Internet-Draft                   WebDAV                    December 2005


   new model more completely, because clients MUST be able to handle
   either model.

   In the original "lock-null resource" model, which is no longer
   recommended for implementation:

   o  A lock-null resource sometimes appeared as "Not Found".  The
      server responds with a 404 or 405 to any method except for PUT,
      MKCOL, OPTIONS, PROPFIND, LOCK, UNLOCK.

   o  A lock-null resource does however show up as a member of its
      parent collection.

   o  The server removes the lock-null resource entirely (its URI
      becomes unmapped) if its lock goes away before it is converted to
      a regular resource.  Recall that locks go away not only when they
      expire or are unlcoked, but are also removed if a resource is
      renamed or moved, or if any parent collection is renamed or moved.

   o  The server converts the lock-null resource into a regular resource
      if a PUT request to the URL is successful.

   o  The server converts the lock-null resource into a collection if a
      MKCOL request to the URL is successful (though interoperability
      experience showed that not all servers followed this requirement).

   o  Property values were defined for DAV:lockdiscovery and DAV:
      supportedlock properties but not necessarily for other properties
      like DAV:getcontenttype.

   In the "locked empty resource" model, which is now the recommended
   implementation, a resource created with a LOCK is empty but otherwise
   behaves in every way as a normal resource.  A locked empty resource:

   o  Can be read, deleted, moved, copied, and in all ways behave as a
      regular resource, not a lock-null resource.

   o  Appears as a member of its parent collection.

   o  SHOULD NOT disappear when its lock goes away (clients must
      therefore be responsible for cleaning up their own mess, as with
      any other operation or any non-empty resource)

   o  SHOULD default to having no content type.

   o  MAY NOT have values for properties like DAV:getcontentlanguage
      which haven't been specified yet by the client.




Dusseault                 Expires July 3, 2006                 [Page 26]

Internet-Draft                   WebDAV                    December 2005


   o  Can be updated (have content added) with a PUT request.  The
      server MUST be able to set the content type as specified in the
      PUT request.

   o  MUST NOT be converted into a collection.  The server MUST fail a
      MKCOL request (as it would with a MKCOL request to any existing
      non-collection resource).

   o  MUST have defined values for DAV:lockdiscovery and DAV:
      supportedlock properties.

   o  The response MUST indicate that a resource was created, by use of
      the "201 Created" response code (a LOCK request to an existing
      resource instead will result in 200 OK).  The body must still
      include the DAV:lockdiscovery property, as with a LOCK request to
      an existing resource.

   The client is expected to update the locked empty resource shortly
   after locking it, using PUT and possibly PROPPATCH.  When the client
   uses PUT to overwrite a locked empty resource the client MUST supply
   a Content-Type if any is known.  If the client supplies a Content-
   Type value the server MUST set that value (this requirement actually
   applies to any resource that is overwritten but is particularly
   necessary for locked empty resources which are initially created with
   no Content-Type).

   Clients can easily interoperate both with servers that support the
   old model "lock-null resources" and the recommended model of "locked
   empty resources" by only attempting PUT after a LOCK to an unmapped
   URL, not MKCOL or GET.

7.7.  Write Locks and Collections

   A write lock on a collection, whether created by a "Depth: 0" or
   "Depth: infinity" lock request, prevents the addition or removal of
   member URLs of the collection by non-lock owners.

   A zero-depth lock on a collection affects changes to the direct
   membership of that collection.  When a principal issues a write
   request to create a new resource in a write locked collection, or
   isses a DELETE, MOVE or other request that would remove an existing
   internal member URL of a write locked collection or change the
   binding name, this request MUST fail if the principal does not
   provide the correct lock token for the locked collection.

   This means that if a collection is locked (depth 0 or infinity), its
   lock-token is required in all these cases:




Dusseault                 Expires July 3, 2006                 [Page 27]

Internet-Draft                   WebDAV                    December 2005


   o  DELETE a collection's direct internal member

   o  MOVE a member out of the collection

   o  MOVE a member into the collection

   o  MOVE to rename a member within a collection

   o  COPY a member into a collection

   o  PUT or MKCOL request which would create a new member.

   The collection's lock token is required in addition to the lock token
   on the internal member itself, if it is locked separately.

   In addition, a depth-infinity lock affects all write operations to
   all descendents of the locked collection.  With a depth-infinity
   lock, the root of the lock is directly locked, and all its
   descendants are indirectly locked.

   o  Any new resource added as a descendent of a depth-infinity locked
      collection becomes indirectly locked.

   o  Any indirectly locked resource moved out of the locked collection
      into an unlocked collection is thereafter unlocked.

   o  Any indirectly locked resource moved out of a locked source
      collection into a depth-infinity locked target collection remains
      indirectly locked but is now within the scope of the lock on the
      target collection (the target collection's lock token will
      thereafter be required to make further changes).

   If a depth-infinity write LOCK request is issued to a collection
   containing member URLs identifying resources that are currently
   locked in a manner which conflicts with the write lock, the request
   MUST fail with a 423 (Locked) status code, and the response SHOULD
   contain the 'lock-token-present' precondition.

   If a lock owner causes the URL of a resource to be added as an
   internal member URL of a depth-infinity locked collection then the
   new resource MUST be automatically added to the lock.  This is the
   only mechanism that allows a resource to be added to a write lock.
   Thus, for example, if the collection /a/b/ is write locked and the
   resource /c is moved to /a/b/c then resource /a/b/c will be added to
   the write lock.






Dusseault                 Expires July 3, 2006                 [Page 28]

Internet-Draft                   WebDAV                    December 2005


7.8.  Write Locks and the If Request Header

   If a user agent is not required to have knowledge about a lock when
   requesting an operation on a locked resource, the following scenario
   might occur.  Program A, run by User A, takes out a write lock on a
   resource.  Program B, also run by User A, has no knowledge of the
   lock taken out by Program A, yet performs a PUT to the locked
   resource.  In this scenario, the PUT succeeds because locks are
   associated with a principal, not a program, and thus program B,
   because it is acting with principal A's credential, is allowed to
   perform the PUT.  However, had program B known about the lock, it
   would not have overwritten the resource, preferring instead to
   present a dialog box describing the conflict to the user.  Due to
   this scenario, a mechanism is needed to prevent different programs
   from accidentally ignoring locks taken out by other programs with the
   same authorization.

   In order to prevent these collisions a lock token MUST be submitted
   by an authorized principal for all locked resources that a method may
   change or the method MUST fail.  A lock token is submitted when it
   appears in an If header.  For example, if a resource is to be moved
   and both the source and destination are locked then two lock tokens
   must be submitted in the if header, one for the source and the other
   for the destination.

7.8.1.  Example - Write Lock

   >>Request

     COPY /~fielding/index.html HTTP/1.1
     Host: www.ics.uci.edu
     Destination: http://www.ics.uci.edu/users/f/fielding/index.html
     If: <http://www.ics.uci.edu/users/f/fielding/index.html>
         (<urn:uuid:f81d4fae-7dec-11d0-a765-00a0c91e6bf6>)

   >>Response

     HTTP/1.1 204 No Content

   In this example, even though both the source and destination are
   locked, only one lock token must be submitted, for the lock on the
   destination.  This is because the source resource is not modified by
   a COPY, and hence unaffected by the write lock.  In this example,
   user agent authentication has previously occurred via a mechanism
   outside the scope of the HTTP protocol, in the underlying transport
   layer.





Dusseault                 Expires July 3, 2006                 [Page 29]

Internet-Draft                   WebDAV                    December 2005


7.9.  Write Locks and COPY/MOVE

   A COPY method invocation MUST NOT duplicate any write locks active on
   the source.  However, as previously noted, if the COPY copies the
   resource into a collection that is locked with "Depth: infinity",
   then the resource will be added to the lock.

   A successful MOVE request on a write locked resource MUST NOT move
   the write lock with the resource.  However, if there is an existing
   lock at the destination, the server MUST add the moved resource to
   the destination lock scope.  For example, if the MOVE makes the
   resource a child of a collection that is locked with "Depth:
   infinity", then the resource will be added to that collection's lock.
   Additionally, if a resource locked with "Depth: infinity" is moved to
   a destination that is within the scope of the same lock (e.g., within
   the URL namespace tree covered by the lock), the moved resource will
   again be a added to the lock.  In both these examples, as specified
   in Section 7.8, an If header must be submitted containing a lock
   token for both the source and destination.

7.10.  Refreshing Write Locks

   A client MUST NOT submit the same write lock request twice.  Note
   that a client is always aware it is resubmitting the same lock
   request because it must include the lock token in the If header in
   order to make the request for a resource that is already locked.

   However, a client may submit a LOCK method with an If header but
   without a body.  This form of LOCK MUST only be used to "refresh" a
   lock.  Meaning, at minimum, that any timers associated with the lock
   MUST be re-set.

   A server may return a Timeout header with a lock refresh that is
   different than the Timeout header returned when the lock was
   originally requested.  Additionally clients may submit Timeout
   headers of arbitrary value with their lock refresh requests.
   Servers, as always, may ignore Timeout headers submitted by the
   client.  Note that timeout is measured in seconds remaining until
   expiration.

   If an error is received in response to a refresh LOCK request the
   client MUST NOT assume that the lock was refreshed.









Dusseault                 Expires July 3, 2006                 [Page 30]

Internet-Draft                   WebDAV                    December 2005


8.  HTTP Methods for Distributed Authoring

8.1.  General Request and Response Handling

8.1.1.  Use of XML

   Some of the following new HTTP methods use XML as a request and
   response format.  All DAV compliant clients and resources MUST use
   XML parsers that are compliant with [XML] and XML Namespaces
   [W3C.REC-xml-names-19990114].  All XML used in either requests or
   responses MUST be, at minimum, well formed and use namespaces
   correctly.  If a server receives XML that is not well-formed then the
   server MUST reject the entire request with a 400 (Bad Request).  If a
   client receives XML that is not well-formed in a response then the
   client MUST NOT assume anything about the outcome of the executed
   method and SHOULD treat the server as malfunctioning.

   Note that processing XML submitted by an untrusted source may cause
   risks connected to privacy, security, and service quality (see
   Section 19).  Servers MAY reject questionable requests (even though
   they consist of well-formed XML), for instance with a 400 (Bad
   Request) status code and an optional response body explaining the
   problem.

8.1.2.  Required Bodies in Requests

   Some of these new methods do not define bodies.  Servers MUST examine
   all requests for a body, even when a body was not expected.  In cases
   where a request body is present but would be ignored by a server, the
   server MUST reject the request with 415 (Unsupported Media Type).
   This informs the client (which may have been attempting to use an
   extension) that the body could not be processed as they intended.

8.1.3.  HTTP Headers for use in WebDAV

   HTTP defines many headers that can be used in WebDAV requests and
   responses.  Not all of these are appropriate in all situations and
   some interactions may be undefined.  Note that HTTP 1.1 requires the
   Date header in all responses if possible (see section 14.18,
   [RFC2616]).

   The server MUST do authorization checks before checking any HTTP
   conditional header.

8.1.4.  ETag

   HTTP 1.1 recommends the use of the ETag header in responses to GET
   and PUT requests.  Correct use of ETags is even more important in a



Dusseault                 Expires July 3, 2006                 [Page 31]

Internet-Draft                   WebDAV                    December 2005


   distributed authoring environment, because ETags are necessary along
   with locks to avoid the lost-update problem.  A client might fail to
   renew a lock, for example when the lock times out and the client is
   accidentally offline or in the middle of a long upload.  When a
   client fails to renew the lock, it's quite possible the resource can
   still be relocked and the user can go on editing, as long as no
   changes were made in the meantime.  ETags are required for the client
   to be able to distinguish this case.  Otherwise, the client is forced
   to ask the user whether to overwrite the resource on the server
   without even being able to tell the user whether it has changed.
   Timestamps do not solve this problem nearly as well as ETags.

   WebDAV servers SHOULD support strong ETags for all resources that may
   be PUT.  If ETags are supported for a resource, the server MUST
   return the ETag header in all PUT and GET responses to that resource.

   Because clients may be forced to prompt users or throw away changed
   content if the ETag changes, a WebDAV server SHOULD NOT change the
   ETag (or the Last-Modified time) for a resource that has an unchanged
   body and location.  The ETag represents the state of the body or
   contents of the resource.  There is no similar way to tell if
   properties have changed.

8.1.5.  Including error response bodies

   HTTP and WebDAV did not use the bodies of most error responses for
   machine-parsable information until DeltaV introduced a mechanism to
   include more specific information in the body of an error response
   (section 1.6 of [RFC3253]).  The error body mechanism is appropriate
   to use with any error response that may take a body but does not
   already have a body defined.  The mechanism is particularly
   appropriate when a status code can mean many things (for example, 400
   Bad Request can mean required headers are missing, headers are
   incorrectly formatted, or much more).  This error body mechanism is
   covered in Section 15

8.2.  PROPFIND

   The PROPFIND method retrieves properties defined on the resource
   identified by the Request-URI, if the resource does not have any
   internal members, or on the resource identified by the Request-URI
   and potentially its member resources, if the resource is a collection
   that has internal member URLs.  All DAV compliant resources MUST
   support the PROPFIND method and the propfind XML element
   (Section 13.20) along with all XML elements defined for use with that
   element.

   A client may submit a Depth header with a value of "0", "1", or



Dusseault                 Expires July 3, 2006                 [Page 32]

Internet-Draft                   WebDAV                    December 2005


   "infinity" with a PROPFIND on a collection resource.  Servers MUST
   support the "0", "1" and "infinity" behaviors on WebDAV-compliant
   resources.  By default, the PROPFIND method without a Depth header
   MUST act as if a "Depth: infinity" header was included.

   A client may submit a 'propfind' XML element in the body of the
   request method describing what information is being requested.  It is
   possible to:

   o  Request particular property values, by naming the properties
      desired within the 'prop' element (the ordering of properties in
      here MAY be ignored by server)

   o  Request all dead property values, by using 'dead-props' element.
      This can be combined with retrieving specific live properties
      named as above.  Servers advertising support for this
      specification MUST support this feature.

   o  Request property values for those properties defined in this
      specification plus dead properties, by using 'allprop' element

   o  Request a list of names of all the properties defined on the
      resource, by using the 'propname' element.

   A client may choose not to submit a request body.  An empty PROPFIND
   request body MUST be treated as if it were an 'allprop' request.

   Note that 'allprop' does not return values for all live properties.
   WebDAV servers increasingly have expensively-calculated or lengthy
   properties (see [RFC3253] and [RFC3744]) and do not return all
   properties already.  Instead, WebDAV clients can use propname
   requests to discover what live properties exist, and request named
   properties when retrieving values.  A WebDAV server MAY omit certain
   live properties from other specifications when responding to an
   'allprop' request from an older client, and MAY return only custom
   (dead) properties and those defined in this specification.

   All servers MUST support returning a response of content type text/
   xml or application/xml that contains a multistatus XML element that
   describes the results of the attempts to retrieve the various
   properties.

   If there is an error retrieving a property then a proper error result
   MUST be included in the response.  A request to retrieve the value of
   a property which does not exist is an error and MUST be noted, if the
   response uses a 'multistatus' XML element, with a 'response' XML
   element which contains a 404 (Not Found) status value.




Dusseault                 Expires July 3, 2006                 [Page 33]

Internet-Draft                   WebDAV                    December 2005


   Consequently, the 'multistatus' XML element for a collection resource
   with member URLs MUST include a 'response' XML element for each
   member URL of the collection, to whatever depth was requested.  Each
   'response' XML element MUST contain an 'href' XML element that
   contains the URL of the resource on which the properties in the prop
   XML element are defined.  Results for a PROPFIND on a collection
   resource with internal member URLs are returned as a flat list whose
   order of entries is not significant.

   Properties may be subject to access control.  In the case of
   'allprop' and 'propname' requests, if a principal does not have the
   right to know whether a particular property exists then the property
   MAY be silently excluded from the response.

   The results of this method SHOULD NOT be cached.

8.2.1.  PROPFIND status codes

   This section, as with similar sections for other methods, provides
   some guidance on error codes and preconditions or postconditions
   (defined in Section 15) that might be particularly useful with
   PROPFIND.

   403 Forbidden - A server MAY reject all PROPFIND requests on
   collections with depth header of "Infinity", in which case it SHOULD
   use this error with the precondition code 'propfind-finite-depth'
   inside the error body.

8.2.2.  Status codes for use with 207 (Multi-Status)

   The following status codes are defined for use within the PROPFIND
   Multi-Status response:

      200 OK - A property exists and/or its value is successfully
      returned.

      401 Unauthorized - The property cannot be viewed without
      appropriate authorization.

      403 Forbidden - The property cannot be viewed regardless of
      authentication.

      404 Not Found - The property does not exist.








Dusseault                 Expires July 3, 2006                 [Page 34]

Internet-Draft                   WebDAV                    December 2005


8.2.3.  Example - Retrieving Named Properties

   >>Request

     PROPFIND /file HTTP/1.1
     Host: www.example.com
     Content-type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propfind xmlns:D="DAV:">
       <D:prop xmlns:R="http://www.example.com/boxschema/">
         <R:bigbox/>
         <R:author/>
         <R:DingALing/>
         <R:Random/>
       </D:prop>
     </D:propfind>

































Dusseault                 Expires July 3, 2006                 [Page 35]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:multistatus xmlns:D="DAV:">
       <D:response xmlns:R="http://www.example.com/boxschema/">
         <D:href>http://www.example.com/file</D:href>
         <D:propstat>
           <D:prop>
             <R:bigbox>
               <R:BoxType>Box type A</R:BoxType>
             </R:bigbox>
             <R:author>
               <R:Name>J.J. Johnson</R:Name>
             </R:author>
           </D:prop>
           <D:status>HTTP/1.1 200 OK</D:status>
         </D:propstat>
         <D:propstat>
           <D:prop><R:DingALing/><R:Random/></D:prop>
           <D:status>HTTP/1.1 403 Forbidden</D:status>
           <D:responsedescription> The user does not have access to the
      DingALing property.
           </D:responsedescription>
         </D:propstat>
       </D:response>
       <D:responsedescription> There has been an access violation error.
       </D:responsedescription>
     </D:multistatus>


   In this example, PROPFIND is executed on a non-collection resource
   http://www.example.com/file.  The propfind XML element specifies the
   name of four properties whose values are being requested.  In this
   case only two properties were returned, since the principal issuing
   the request did not have sufficient access rights to see the third
   and fourth properties.











Dusseault                 Expires July 3, 2006                 [Page 36]

Internet-Draft                   WebDAV                    December 2005


8.2.4.  Example - Retrieving Named and Dead Properties

   >>Request

     PROPFIND /mycol/ HTTP/1.1
     Host: www.example.com
     Depth: 1
     Content-type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propfind xmlns:D="DAV:">
       <D:prop>
         <D:creationdate/>
         <D:getlastmodified/>
       </D:prop>
       <D:dead-props/>
     </D:propfind>

   In this example, PROPFIND is executed on a collection resource
   http://www.example.com/mycol/.  The client requests the values of two
   specific live properties plus all dead properties (names and values).
   The response is not shown.

8.2.5.  Example - Using 'propname' to Retrieve all Property Names

   >>Request

     PROPFIND /container/ HTTP/1.1
     Host: www.example.com
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <propfind xmlns="DAV:">
       <propname/>
     </propfind>














Dusseault                 Expires July 3, 2006                 [Page 37]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <multistatus xmlns="DAV:">
       <response>
         <href>http://www.example.com/container/</href>
         <propstat>
           <prop xmlns:R="http://www.example.com/boxschema/">
             <R:bigbox/>
             <R:author/>
             <creationdate/>
             <displayname/>
             <resourcetype/>
             <supportedlock/>
           </prop>
           <status>HTTP/1.1 200 OK</status>
         </propstat>
       </response>
       <response>
         <href>http://www.example.com/container/front.html</href>
         <propstat>
           <prop xmlns:R="http://www.example.com/boxschema/">
             <R:bigbox/>
             <creationdate/>
             <displayname/>
             <getcontentlength/>
             <getcontenttype/>
             <getetag/>
             <getlastmodified/>
             <resourcetype/>
             <supportedlock/>
           </prop>
           <status>HTTP/1.1 200 OK</status>
         </propstat>
       </response>
     </multistatus>

   In this example, PROPFIND is invoked on the collection resource
   http://www.example.com/container/, with a propfind XML element
   containing the propname XML element, meaning the name of all
   properties should be returned.  Since no Depth header is present, it
   assumes its default value of "infinity", meaning the name of the
   properties on the collection and all its descendents should be
   returned.



Dusseault                 Expires July 3, 2006                 [Page 38]

Internet-Draft                   WebDAV                    December 2005


   Consistent with the previous example, resource
   http://www.example.com/container/ has six properties defined on it:
   bigbox and author in the "http://www.example.com/boxschema/"
   namespace, and creationdate, displayname, resourcetype, and
   supportedlock in the "DAV:" namespace.

   The resource http://www.example.com/container/index.html, a member of
   the "container" collection, has nine properties defined on it, bigbox
   in the "http://www.example.com/boxschema/" namespace and,
   creationdate, displayname, getcontentlength, getcontenttype, getetag,
   getlastmodified, resourcetype, and supportedlock in the "DAV:"
   namespace.

   This example also demonstrates the use of XML namespace scoping and
   the default namespace.  Since the "xmlns" attribute does not contain
   a prefix, the namespace applies by default to all enclosed elements.
   Hence, all elements which do not explicitly state the namespace to
   which they belong are members of the "DAV:" namespace.

8.2.6.  Example - Using 'allprop'

   Note that 'allprop', despite its name which remains for backward-
   compatibility, does not return every property, but only dead
   properties and the live properties defined in this specification.

   >>Request

     PROPFIND /container/ HTTP/1.1
     Host: www.example.com
     Depth: 1
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propfind xmlns:D="DAV:">
       <D:allprop/>
     </D:propfind>


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:multistatus xmlns:D="DAV:">
       <D:response>



Dusseault                 Expires July 3, 2006                 [Page 39]

Internet-Draft                   WebDAV                    December 2005


         <D:href>/container/</D:href>
         <D:propstat>
           <D:prop xmlns:R="http://www.foo.bar/boxschema/">
             <R:bigbox><R:BoxType>Box type A</R:BoxType></R:bigbox>
             <R:author><R:Name>Hadrian</R:Name></R:author>
             <D:creationdate>1997-12-01T17:42:21-08:00</D:creationdate>
             <D:displayname>Example collection</D:displayname>
             <D:resourcetype><D:collection/></D:resourcetype>
             <D:supportedlock>
               <D:lockentry>
                 <D:lockscope><D:exclusive/></D:lockscope>
                 <D:locktype><D:write/></D:locktype>
               </D:lockentry>
               <D:lockentry>
                 <D:lockscope><D:shared/></D:lockscope>
                 <D:locktype><D:write/></D:locktype>
               </D:lockentry>
             </D:supportedlock>
           </D:prop>
           <D:status>HTTP/1.1 200 OK</D:status>
         </D:propstat>
       </D:response>
       <D:response>
         <D:href>/container/front.html</D:href>
         <D:propstat>
           <D:prop xmlns:R="http://www.foo.bar/boxschema/">
             <R:bigbox><R:BoxType>Box type B</R:BoxType>
             </R:bigbox>
             <D:creationdate>1997-12-01T18:27:21-08:00</D:creationdate>
             <D:displayname>Example HTML resource</D:displayname>
             <D:getcontentlength>4525</D:getcontentlength>
             <D:getcontenttype>text/html</D:getcontenttype>
             <D:getetag>"zzyzx"</D:getetag>
             <D:getlastmodified
               >Monday, 12-Jan-98 09:25:56 GMT</D:getlastmodified>
             <D:resourcetype/>
             <D:supportedlock>
               <D:lockentry>
                 <D:lockscope><D:exclusive/></D:lockscope>
                 <D:locktype><D:write/></D:locktype>
               </D:lockentry>
               <D:lockentry>
                 <D:lockscope><D:shared/></D:lockscope>
                 <D:locktype><D:write/></D:locktype>
               </D:lockentry>
             </D:supportedlock>
           </D:prop>
           <D:status>HTTP/1.1 200 OK</D:status>



Dusseault                 Expires July 3, 2006                 [Page 40]

Internet-Draft                   WebDAV                    December 2005


         </D:propstat>
       </D:response>
     </D:multistatus>

   In this example, PROPFIND was invoked on the resource
   http://www.foo.bar/container/ with a Depth header of 1, meaning the
   request applies to the resource and its children, and a propfind XML
   element containing the allprop XML element, meaning the request
   should return the name and value of all the dead properties defined
   on the resources, plus the name and value of all the properties
   defined in this specification.  This example illustrates the use of
   relative references in the 'href' elements of the response.

   The resource http://www.foo.bar/container/ has six properties defined
   on it: 'bigbox' and 'author in the "http://www.foo.bar/boxschema/"
   namespace, DAV:creationdate, DAV:displayname, DAV:resourcetype, and
   DAV:supportedlock.

   The last four properties are WebDAV-specific, defined in Section 14.
   Since GET is not supported on this resource, the get* properties
   (e.g., DAV:getcontentlength) are not defined on this resource.  The
   WebDAV-specific properties assert that "container" was created on
   December 1, 1997, at 5:42:21PM, in a time zone 8 hours west of GMT
   (DAV:creationdate), has a name of "Example collection" (DAV:
   displayname), a collection resource type (DAV:resourcetype), and
   supports exclusive write and shared write locks (DAV:supportedlock).

   The resource http://www.foo.bar/container/front.html has nine
   properties defined on it:

   'bigbox' in the "http://www.foo.bar/boxschema/" namespace (another
   instance of the "bigbox" property type), DAV:creationdate, DAV:
   displayname, DAV:getcontentlength, DAV:getcontenttype, DAV:getetag,
   DAV:getlastmodified, DAV:resourcetype, and DAV:supportedlock.

   The DAV-specific properties assert that "front.html" was created on
   December 1, 1997, at 6:27:21PM, in a time zone 8 hours west of GMT
   (DAV:creationdate), has a name of "Example HTML resource" (DAV:
   displayname), a content length of 4525 bytes (DAV:getcontentlength),
   a MIME type of "text/html" (DAV:getcontenttype), an entity tag of
   "zzyzx" (DAV:getetag), was last modified on Monday, January 12, 1998,
   at 09:25:56 GMT (DAV:getlastmodified), has an empty resource type,
   meaning that it is not a collection (DAV:resourcetype), and supports
   both exclusive write and shared write locks (DAV:supportedlock).

8.3.  PROPPATCH

   The PROPPATCH method processes instructions specified in the request



Dusseault                 Expires July 3, 2006                 [Page 41]

Internet-Draft                   WebDAV                    December 2005


   body to set and/or remove properties defined on the resource
   identified by the Request-URI.

   All DAV compliant resources MUST support the PROPPATCH method and
   MUST process instructions that are specified using the
   propertyupdate, set, and remove XML elements.  Execution of the
   directives in this method is, of course, subject to access control
   constraints.  DAV compliant resources SHOULD support the setting of
   arbitrary dead properties.

   The request message body of a PROPPATCH method MUST contain the
   propertyupdate XML element.  Instruction processing MUST occur in
   document order (an exception to the normal rule that ordering is
   irrelevant).  Instructions MUST either all be executed or none
   executed.  Thus if any error occurs during processing all executed
   instructions MUST be undone and a proper error result returned.
   Instruction processing details can be found in the definition of the
   set and remove instructions in Section 13.23 and Section 13.26.

8.3.1.  Status Codes for use in 207 (Multi-Status)

   The following are examples of response codes one would expect to be
   used in a 207 (Multi-Status) response for this method.  Note,
   however, that unless explicitly prohibited any 2/3/4/5xx series
   response code may be used in a 207 (Multi-Status) response.

   200 (OK) - The property set or change succeeded.  Note that if this
   appears for one property, it appears for every property in the
   response, due to the atomicity of PROPPATCH.

   403 (Forbidden) - The client, for reasons the server chooses not to
   specify, cannot alter one of the properties.

   403 (Forbidden): The client has attempted to set a read-only
   property, such as DAV:getetag.  If returning this error, the server
   SHOULD use the precondition code 'writable-property' inside the
   response body.

   409 (Conflict) - The client has provided a value whose semantics are
   not appropriate for the property.

   424 (Failed Dependency) - The property change could not be made
   because of another property change that failed.

   507 (Insufficient Storage) - The server did not have sufficient space
   to record the property.





Dusseault                 Expires July 3, 2006                 [Page 42]

Internet-Draft                   WebDAV                    December 2005


8.3.2.  Example - PROPPATCH

   >>Request

     PROPPATCH /bar.html HTTP/1.1
     Host: www.example.com
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propertyupdate xmlns:D="DAV:"
                       xmlns:Z="http://www.w3.com/standards/z39.50/">
       <D:set>
         <D:prop>
           <Z:authors>
             <Z:Author>Jim Whitehead</Z:Author>
             <Z:Author>Roy Fielding</Z:Author>
           </Z:authors>
         </D:prop>
       </D:set>
       <D:remove>
         <D:prop><Z:Copyright-Owner/></D:prop>
       </D:remove>
     </D:propertyupdate>



























Dusseault                 Expires July 3, 2006                 [Page 43]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:multistatus xmlns:D="DAV:"
                    xmlns:Z="http://www.w3.com/standards/z39.50">
       <D:response>
         <D:href>http://www.example.com/bar.html</D:href>
         <D:propstat>
           <D:prop><Z:Authors/></D:prop>
           <D:status>HTTP/1.1 424 Failed Dependency</D:status>
         </D:propstat>
         <D:propstat>
           <D:prop><Z:Copyright-Owner/></D:prop>
           <D:status>HTTP/1.1 409 Conflict</D:status>
         </D:propstat>
         <D:responsedescription> Copyright Owner can not be deleted or
           altered.</D:responsedescription>
       </D:response>
     </D:multistatus>

   In this example, the client requests the server to set the value of
   the "Authors" property in the "http://www.w3.com/standards/z39.50/"
   namespace, and to remove the property "Copyright-Owner" in the
   "http://www.w3.com/standards/z39.50/" namespace.  Since the
   Copyright-Owner property could not be removed, no property
   modifications occur.  The 424 (Failed Dependency) status code for the
   Authors property indicates this action would have succeeded if it
   were not for the conflict with removing the Copyright-Owner property.

8.4.  MKCOL Method

   The MKCOL method is used to create a new collection.  All WebDAV
   compliant resources MUST support the MKCOL method.

   MKCOL creates a new collection resource at the location specified by
   the Request-URI.  If the Request-URI is already mapped to a resource
   then the MKCOL MUST fail.  During MKCOL processing, a server MUST
   make the Request-URI a member of its parent collection, unless the
   Request-URI is "/".  If no such ancestor exists, the method MUST
   fail.  When the MKCOL operation creates a new collection resource,
   all ancestors MUST already exist, or the method MUST fail with a 409
   (Conflict) status code.  For example, if a request to create
   collection /a/b/c/d/ is made, and /a/b/c/ does not exist, the request
   must fail.



Dusseault                 Expires July 3, 2006                 [Page 44]

Internet-Draft                   WebDAV                    December 2005


   When MKCOL is invoked without a request body, the newly created
   collection SHOULD have no members.

   A MKCOL request message may contain a message body.  The precise
   behavior of a MKCOL request when the body is present is undefined,
   but limited to creating collections, members of a collection, bodies
   of members and properties on the collections or members.  If the
   server receives a MKCOL request entity type it does not support or
   understand it MUST respond with a 415 (Unsupported Media Type) status
   code.  If the server decides to reject the request based on the
   presence of an entity or the type of an entity, it should use the 415
   (Unsupported Media Type) status code.

8.4.1.  MKCOL Status Codes

   Responses from a MKCOL request MUST NOT be cached as MKCOL has non-
   idempotent semantics.  In addition to the general status codes
   possible, the following status codes have specific applicability to
   MKCOL:

   201 (Created) - The collection was created.

   403 (Forbidden) - This indicates at least one of two conditions: 1)
   the server does not allow the creation of collections at the given
   location in its URL namespace, or 2) the parent collection of the
   Request-URI exists but cannot accept members.

   405 (Method Not Allowed) - MKCOL can only be executed on an unmapped
   URL.

   409 (Conflict) - A collection cannot be made at the Request-URI until
   one or more intermediate collections have been created.  The server
   MUST NOT create those intermediate collections automatically.

   415 (Unsupported Media Type) - The server does not support the
   request body type (since this specification does not define any body
   for MKCOL requests).

   507 (Insufficient Storage) - The resource does not have sufficient
   space to record the state of the resource after the execution of this
   method.

8.4.2.  Example - MKCOL

   This example creates a collection called /webdisc/xfiles/ on the
   server www.example.com.





Dusseault                 Expires July 3, 2006                 [Page 45]

Internet-Draft                   WebDAV                    December 2005


   >>Request

     MKCOL /webdisc/xfiles/ HTTP/1.1
     Host: www.example.com


   >>Response

     HTTP/1.1 201 Created

8.5.  GET, HEAD for Collections

   The semantics of GET are unchanged when applied to a collection,
   since GET is defined as, "retrieve whatever information (in the form
   of an entity) is identified by the Request-URI" [RFC2616].  GET when
   applied to a collection may return the contents of an "index.html"
   resource, a human-readable view of the contents of the collection, or
   something else altogether.  Hence it is possible that the result of a
   GET on a collection will bear no correlation to the membership of the
   collection.

   Similarly, since the definition of HEAD is a GET without a response
   message body, the semantics of HEAD are unmodified when applied to
   collection resources.

8.6.  POST for Collections

   Since by definition the actual function performed by POST is
   determined by the server and often depends on the particular
   resource, the behavior of POST when applied to collections cannot be
   meaningfully modified because it is largely undefined.  Thus the
   semantics of POST are unmodified when applied to a collection.

8.7.  DELETE

   DELETE is defined in [RFC2616], section 9.7, to "delete the resource
   identified by the Request-URI".  However, WebDAV changes some DELETE
   handling requirements.

   A server processing a successful DELETE request:

      MUST destroy locks rooted on the deleted resource

      MUST remove the mapping from the Request-URI to any resource.

   Thus, after a successful DELETE operation (and in the absence of
   other actions) a subsequent GET/HEAD/PROPFIND request to the target
   Request-URI MUST return 404 (Not Found).



Dusseault                 Expires July 3, 2006                 [Page 46]

Internet-Draft                   WebDAV                    December 2005


8.7.1.  DELETE for Collections

   The DELETE method on a collection MUST act as if a "Depth: infinity"
   header was used on it.  A client MUST NOT submit a Depth header with
   a DELETE on a collection with any value but infinity.

   DELETE instructs that the collection specified in the Request-URI and
   all resources identified by its internal member URLs are to be
   deleted.

   If any resource identified by a member URL cannot be deleted then all
   of the member's ancestors MUST NOT be deleted, so as to maintain URL
   namespace consistency.

   Any headers included with DELETE MUST be applied in processing every
   resource to be deleted.

   When the DELETE method has completed processing it MUST result in a
   consistent URL namespace.

   If an error occurs deleting an internal resource (a resource other
   than the resource identified in the Request-URI) then the response
   can be a 207 (Multi-Status).  Multi-Status is used here to indicate
   which internal resources could NOT be deleted, including an error
   code which should help the client understand which resources caused
   the failure.  For example, the Multi-Status body could include a
   response with status 423 (Locked) if an internal resource was locked.

   The server MAY return a 4xx status response, rather than a 207, if
   the request failed completely.

   424 (Failed Dependency) status codes SHOULD NOT be in the 207 (Multi-
   Status) response for DELETE.  They can be safely left out because the
   client will know that the ancestors of a resource could not be
   deleted when the client receives an error for the ancestor's progeny.
   Additionally 204 (No Content) errors SHOULD NOT be returned in the
   207 (Multi-Status).  The reason for this prohibition is that 204 (No
   Content) is the default success code.

8.7.2.  Example - DELETE

   >>Request

     DELETE  /container/ HTTP/1.1
     Host: www.example.com






Dusseault                 Expires July 3, 2006                 [Page 47]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <d:multistatus xmlns:d="DAV:">
       <d:response>
         <d:href>http://www.example.com/container/resource3</d:href>
         <d:status>HTTP/1.1 423 Locked</d:status>
       </d:response>
     </d:multistatus>

   In this example the attempt to delete
   http://www.example.com/container/resource3 failed because it is
   locked, and no lock token was submitted with the request.
   Consequently, the attempt to delete http://www.example.com/container/
   also failed.  Thus the client knows that the attempt to delete
   http://www.example.com/container/ must have also failed since the
   parent can not be deleted unless its child has also been deleted.
   Even though a Depth header has not been included, a depth of infinity
   is assumed because the method is on a collection.

8.8.  PUT

8.8.1.  PUT for Non-Collection Resources

   A PUT performed on an existing resource replaces the GET response
   entity of the resource.  Properties defined on the resource may be
   recomputed during PUT processing but are not otherwise affected.  For
   example, if a server recognizes the content type of the request body,
   it may be able to automatically extract information that could be
   profitably exposed as properties.

   A PUT that would result in the creation of a resource without an
   appropriately scoped parent collection MUST fail with a 409
   (Conflict).

8.8.2.  PUT for Collections

   This specification does not define the behavior of the PUT method for
   existing collections.  A PUT request to an existing collection MAY be
   treated as an error (405 Method Not Allowed).

   The MKCOL method is defined to create collections.





Dusseault                 Expires July 3, 2006                 [Page 48]

Internet-Draft                   WebDAV                    December 2005


8.9.  COPY

   The COPY method creates a duplicate of the source resource identified
   by the Request-URI, in the destination resource identified by the URI
   in the Destination header.  The Destination header MUST be present.
   The exact behavior of the COPY method depends on the type of the
   source resource.

   All WebDAV compliant resources MUST support the COPY method.
   However, support for the COPY method does not guarantee the ability
   to copy a resource.  For example, separate programs may control
   resources on the same server.  As a result, it may not be possible to
   copy a resource to a location that appears to be on the same server.

8.9.1.  COPY for Non-collection Resources

   When the source resource is not a collection the result of the COPY
   method is the creation of a new resource at the destination whose
   state and behavior match that of the source resource as closely as
   possible.  Since the environment at the destination may be different
   than at the source due to factors outside the scope of control of the
   server, such as the absence of resources required for correct
   operation, it may not be possible to completely duplicate the
   behavior of the resource at the destination.  Subsequent alterations
   to the destination resource will not modify the source resource.
   Subsequent alterations to the source resource will not modify the
   destination resource.

8.9.2.  COPY for Properties

   After a successful COPY invocation, all dead properties on the source
   resource MUST be duplicated on the destination resource, along with
   all properties as appropriate.  Live properties described in this
   document SHOULD be duplicated as identically behaving live properties
   at the destination resource, but not necessarily with the same
   values.  Servers SHOULD NOT convert live properties into dead
   properties on the destination resource, because clients may then draw
   incorrect conclusions about the state or functionality of a resource.
   Note that some live properties are defined such that the absence of
   the property has a specific meaning (e.g. a flag with one meaning if
   present and the opposite if absent), and in these cases, a successful
   COPY might result in the property being reported as "Not Found" in
   subsequent requests.

   A COPY operation creates a new resource, much like a PUT operation
   does.  Live properties which are related to resource creation (such
   as DAV:creationdate) should have their values set accordingly.




Dusseault                 Expires July 3, 2006                 [Page 49]

Internet-Draft                   WebDAV                    December 2005


8.9.3.  COPY for Collections

   The COPY method on a collection without a Depth header MUST act as if
   a Depth header with value "infinity" was included.  A client may
   submit a Depth header on a COPY on a collection with a value of "0"
   or "infinity".  Servers MUST support the "0" and "infinity" Depth
   header behaviors on WebDAV-compliant resources.

   A COPY of depth infinity instructs that the collection resource
   identified by the Request-URI is to be copied to the location
   identified by the URI in the Destination header, and all its internal
   member resources are to be copied to a location relative to it,
   recursively through all levels of the collection hierarchy.  Note
   that a depth infinity COPY of /A/ into /A/B/ could lead to infinite
   recursion if not handled correctly.

   A COPY of "Depth: 0" only instructs that the collection and its
   properties but not resources identified by its internal member URLs,
   are to be copied.

   Any headers included with a COPY MUST be applied in processing every
   resource to be copied with the exception of the Destination header.

   The Destination header only specifies the destination URI for the
   Request-URI.  When applied to members of the collection identified by
   the Request-URI the value of Destination is to be modified to reflect
   the current location in the hierarchy.  So, if the Request-URI is /a/
   with Host header value http://example.com/ and the Destination is
   http://example.com/b/ then when http://example.com/a/c/d is processed
   it must use a Destination of http://example.com/b/c/d.

   When the COPY method has completed processing it MUST have created a
   consistent URL namespace at the destination (see Section 5.1 for the
   definition of namespace consistency).  However, if an error occurs
   while copying an internal collection, the server MUST NOT copy any
   resources identified by members of this collection (i.e., the server
   must skip this subtree), as this would create an inconsistent
   namespace.  After detecting an error, the COPY operation SHOULD try
   to finish as much of the original copy operation as possible (i.e.,
   the server should still attempt to copy other subtrees and their
   members, that are not descendents of an error-causing collection).

   So, for example, if an infinite depth copy operation is performed on
   collection /a/, which contains collections /a/b/ and /a/c/, and an
   error occurs copying /a/b/, an attempt should still be made to copy
   /a/c/.  Similarly, after encountering an error copying a non-
   collection resource as part of an infinite depth copy, the server
   SHOULD try to finish as much of the original copy operation as



Dusseault                 Expires July 3, 2006                 [Page 50]

Internet-Draft                   WebDAV                    December 2005


   possible.

   If an error in executing the COPY method occurs with a resource other
   than the resource identified in the Request-URI then the response
   MUST be a 207 (Multi-Status), and the URL of the resource causing the
   failure MUST appear with the specific error.

   The 424 (Failed Dependency) status code SHOULD NOT be returned in the
   207 (Multi-Status) response from a COPY method.  These responses can
   be safely omitted because the client will know that the progeny of a
   resource could not be copied when the client receives an error for
   the parent.  Additionally 201 (Created)/204 (No Content) status codes
   SHOULD NOT be returned as values in 207 (Multi-Status) responses from
   COPY methods.  They, too, can be safely omitted because they are the
   default success codes.

8.9.4.  COPY and Overwriting Destination Resources

   If a COPY request has an Overwrite header with a value of "F", and a
   resource exists at the Destination URL, the server MUST fail the
   request.

   When a server executes a COPY request and overwrites a destination
   resource, the exact behavior MAY depend on many factors, including
   WebDAV extension capabilities (see particularly [RFC3253]).  For
   example, when an ordinary resource is overwritten, the server could
   delete the target resource before doing the copy, or could do an in-
   place overwrite to preserve live properties.

   When a collection is overwritten, the membership of the destination
   collection after the successful COPY request MUST be the same
   membership as the source collection immediately before the COPY.
   Thus, merging the membership of the source and destination
   collections together in the destination is not a compliant behavior.

   In general, if clients require the state of the destination URL to be
   wiped out prior to a COPY (e.g. to force live properties to be
   reset), then the client could send a DELETE to the destination before
   the COPY request to ensure this reset.

8.9.5.  Status Codes

   In addition to the general status codes possible, the following
   status codes have specific applicability to COPY:

   201 (Created) - The source resource was successfully copied.  The
   COPY operation resulted in the creation of a new resource.




Dusseault                 Expires July 3, 2006                 [Page 51]

Internet-Draft                   WebDAV                    December 2005


   204 (No Content) - The source resource was successfully copied to a
   pre-existing destination resource.

   207 (Multi-Status) - Multiple resources were to be affected by the
   COPY, but errors on some of them prevented the operation from taking
   place.  Specific error messages, together with the most appropriate
   of the source and destination URLs, appear in the body of the multi-
   status response.  E.g. if a destination resource was locked and could
   not be overwritten, then the destination resource URL appears with
   the 423 (Locked) status.

   403 (Forbidden) - The operation is forbidden.  A special case for
   COPY could be that the source and destination resources are the same
   resource.

   409 (Conflict) - A resource cannot be created at the destination
   until one or more intermediate collections have been created.  The
   server MUST NOT create those intermediate collections automatically.

   412 (Precondition Failed) - A precondition header check failed, e.g.
   the Overwrite header is "F" and the destination URL is already mapped
   to a resource.

   423 (Locked) - The destination resource, or resource within the
   destination collection, was locked.  This response SHOULD contain the
   'lock-token-present' precondition element.

   502 (Bad Gateway) - This may occur when the destination is on another
   server, repository or URL namespace.  Either the source namespace
   does not support copying to the destination namespace, or the
   destination namespace refuses to accept the resource.  The client may
   wish to try GET/PUT and PROPFIND/PROPPATCH instead.

   507 (Insufficient Storage) - The destination resource does not have
   sufficient space to record the state of the resource after the
   execution of this method.

8.9.6.  Example - COPY with Overwrite

   This example shows resource
   http://www.ics.uci.edu/~fielding/index.html being copied to the
   location http://www.ics.uci.edu/users/f/fielding/index.html.  The 204
   (No Content) status code indicates the existing resource at the
   destination was overwritten.







Dusseault                 Expires July 3, 2006                 [Page 52]

Internet-Draft                   WebDAV                    December 2005


   >>Request

     COPY /~fielding/index.html HTTP/1.1
     Host: www.ics.uci.edu
     Destination: http://www.ics.uci.edu/users/f/fielding/index.html

   >>Response

     HTTP/1.1 204 No Content

8.9.7.  Example - COPY with No Overwrite

   The following example shows the same copy operation being performed,
   but with the Overwrite header set to "F." A response of 412
   (Precondition Failed) is returned because the destination URL is
   already mapped to a resource.

   >>Request

     COPY /~fielding/index.html HTTP/1.1
     Host: www.ics.uci.edu
     Destination: http://www.ics.uci.edu/users/f/fielding/index.html
     Overwrite: F

   >>Response

     HTTP/1.1 412 Precondition Failed

8.9.8.  Example - COPY of a Collection

   >>Request

     COPY /container/ HTTP/1.1
     Host: www.example.com
     Destination: http://www.example.com/othercontainer/
     Depth: infinity















Dusseault                 Expires July 3, 2006                 [Page 53]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>

     <d:multistatus xmlns:d="DAV:">
       <d:response>
         <d:href>http://www.example.com/othercontainer/R2/</d:href>
         <d:status>HTTP/1.1 423 Locked</d:status>
       </d:response>
     </d:multistatus>

   The Depth header is unnecessary as the default behavior of COPY on a
   collection is to act as if a "Depth: infinity" header had been
   submitted.  In this example most of the resources, along with the
   collection, were copied successfully.  However the collection R2
   failed because the destination R2 is locked.  Because there was an
   error copying R2, none of R2's members were copied.  However no
   errors were listed for those members due to the error minimization
   rules.

8.10.  MOVE

   The MOVE operation on a non-collection resource is the logical
   equivalent of a copy (COPY), followed by consistency maintenance
   processing, followed by a delete of the source, where all three
   actions are performed atomically.  The consistency maintenance step
   allows the server to perform updates caused by the move, such as
   updating all URLs other than the Request-URI which identify the
   source resource, to point to the new destination resource.
   Consequently, the Destination header MUST be present on all MOVE
   methods and MUST follow all COPY requirements for the COPY part of
   the MOVE method.  All WebDAV compliant resources MUST support the
   MOVE method.  However, support for the MOVE method does not guarantee
   the ability to move a resource to a particular destination.

   For example, separate programs may actually control different sets of
   resources on the same server.  Therefore, it may not be possible to
   move a resource within a namespace that appears to belong to the same
   server.

   If a resource exists at the destination, the destination resource
   will be deleted as a side-effect of the MOVE operation, subject to
   the restrictions of the Overwrite header.




Dusseault                 Expires July 3, 2006                 [Page 54]

Internet-Draft                   WebDAV                    December 2005


8.10.1.  MOVE for Properties

   Live properties described in this document SHOULD be moved along with
   the resource, such that the resource has identically behaving live
   properties at the destination resource, but not necessarily with the
   same values.  Note that some live properties are defined such that
   the absence of the property has a specific meaning (e.g. a flag with
   one meaning if present and the opposite if absent), and in these
   cases, a successful MOVE might result in the property being reported
   as "Not Found" in subsequent requests.  If the live properties will
   not work the same way at the destination, the server MAY fail the
   request.

   MOVE is frequently used by clients to rename a file without changing
   its parent collection, so it's not appropriate to reset all live
   properties which are set at resource creation.  For example, the DAV:
   creationdate property value SHOULD remain the same after a MOVE.

   Dead properties MUST be moved along with the resource.

8.10.2.  MOVE for Collections

   A MOVE with "Depth: infinity" instructs that the collection
   identified by the Request-URI be moved to the address specified in
   the Destination header, and all resources identified by its internal
   member URLs are to be moved to locations relative to it, recursively
   through all levels of the collection hierarchy.

   The MOVE method on a collection MUST act as if a "Depth: infinity"
   header was used on it.  A client MUST NOT submit a Depth header on a
   MOVE on a collection with any value but "infinity".

   Any headers included with MOVE MUST be applied in processing every
   resource to be moved with the exception of the Destination header.
   The behavior of the Destination header is the same as given for COPY
   on collections.

   When the MOVE method has completed processing it MUST have created a
   consistent URL namespace at both the source and destination (see
   section 5.1 for the definition of namespace consistency).  However,
   if an error occurs while moving an internal collection, the server
   MUST NOT move any resources identified by members of the failed
   collection (i.e., the server must skip the error-causing subtree), as
   this would create an inconsistent namespace.  In this case, after
   detecting the error, the move operation SHOULD try to finish as much
   of the original move as possible (i.e., the server should still
   attempt to move other subtrees and the resources identified by their
   members, that are not descendents of an error-causing collection).



Dusseault                 Expires July 3, 2006                 [Page 55]

Internet-Draft                   WebDAV                    December 2005


   So, for example, if an infinite depth move is performed on collection
   /a/, which contains collections /a/b/ and /a/c/, and an error occurs
   moving /a/b/, an attempt should still be made to try moving /a/c/.
   Similarly, after encountering an error moving a non-collection
   resource as part of an infinite depth move, the server SHOULD try to
   finish as much of the original move operation as possible.

   If an error occurs with a resource other than the resource identified
   in the Request-URI then the response MUST be a 207 (Multi-Status),
   and the errored resource's URL MUST appear with the specific error.

   The 424 (Failed Dependency) status code SHOULD NOT be returned in the
   207 (Multi-Status) response from a MOVE method.  These errors can be
   safely omitted because the client will know that the progeny of a
   resource could not be moved when the client receives an error for the
   parent.  Additionally 201 (Created)/204 (No Content) responses SHOULD
   NOT be returned as values in 207 (Multi-Status) responses from a
   MOVE.  These responses can be safely omitted because they are the
   default success codes.

8.10.3.  MOVE and the Overwrite Header

   If a resource exists at the destination and the Overwrite header is
   "T" then prior to performing the move the server MUST perform a
   DELETE with "Depth: infinity" on the destination resource.  If the
   Overwrite header is set to "F" then the operation will fail.

8.10.4.  Status Codes

   In addition to the general status codes possible, the following
   status codes have specific applicability to MOVE:

   201 (Created) - The source resource was successfully moved, and a new
   URL mapping was created at the destination.

   204 (No Content) - The source resource was successfully moved to a
   URL that was already mapped.

   207 (Multi-Status) - Multiple resources were to be affected by the
   MOVE, but errors on some of them prevented the operation from taking
   place.  Specific error messages, together with the most appropriate
   of the source and destination URLs, appear in the body of the multi-
   status response.  E.g. if a source resource was locked and could not
   be moved, then the source resource URL appears with the 423 (Locked)
   status.

   403 (Forbidden) - Among many possible reasons for forbidding a MOVE
   operation, this status code is recommended for use when the source



Dusseault                 Expires July 3, 2006                 [Page 56]

Internet-Draft                   WebDAV                    December 2005


   and destination resources are the same.

   409 (Conflict) - A resource cannot be created at the destination
   until one or more intermediate collections have been created.  The
   server MUST NOT create those intermediate collections automatically.
   Or, the server was unable to preserve the behavior of the live
   properties and still move the resource to the destination (see
   'preserved-live-properties' postcondition).

   412 (Precondition Failed) - A condition header failed.  Specific to
   MOVE, this could mean that the Overwrite header is "F" and the state
   of the destination URL is already mapped to a resource.

   423 (Locked) - The source or the destination resource, the source or
   destination resource parent, or some resource within the source or
   destination collection, was locked.  This response SHOULD contain the
   'lock-token-present' precondition element.

   502 (Bad Gateway) - This may occur when the destination is on another
   server and the destination server refuses to accept the resource.
   This could also occur when the destination is on another sub-section
   of the same server namespace.

8.10.5.  Example - MOVE of a Non-Collection

   This example shows resource
   http://www.ics.uci.edu/~fielding/index.html being moved to the
   location http://www.ics.uci.edu/users/f/fielding/index.html.  The
   contents of the destination resource would have been overwritten if
   the destination URL was already mapped to a resource.  In this case,
   since there was nothing at the destination resource, the response
   code is 201 (Created).

   >>Request

     MOVE /~fielding/index.html HTTP/1.1
     Host: www.ics.uci.edu
     Destination: http://www.ics.uci.edu/users/f/fielding/index.html

   >>Response

     HTTP/1.1 201 Created
     Location: http://www.ics.uci.edu/users/f/fielding/index.html








Dusseault                 Expires July 3, 2006                 [Page 57]

Internet-Draft                   WebDAV                    December 2005


8.10.6.  Example - MOVE of a Collection

   >>Request

     MOVE /container/ HTTP/1.1
     Host: www.example.com
     Destination: http://www.example.com/othercontainer/
     Overwrite: F
     If: (<urn:uuid:fe184f2e-6eec-41d0-c765-01adc56e6bb4>)
        (<urn:uuid:e454f3f3-acdc-452a-56c7-00a5c91e4b77>)

   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <d:multistatus xmlns:d='DAV:'>
       <d:response>
         <d:href>http://www.example.com/othercontainer/C2/</d:href>
         <d:status>HTTP/1.1 423 Locked</d:status>
       </d:response>
     </d:multistatus>

   In this example the client has submitted a number of lock tokens with
   the request.  A lock token will need to be submitted for every
   resource, both source and destination, anywhere in the scope of the
   method, that is locked.  In this case the proper lock token was not
   submitted for the destination
   http://www.example.com/othercontainer/C2/.  This means that the
   resource /container/C2/ could not be moved.  Because there was an
   error moving /container/C2/, none of /container/C2's members were
   moved.  However no errors were listed for those members due to the
   error minimization rules.  User agent authentication has previously
   occurred via a mechanism outside the scope of the HTTP protocol, in
   an underlying transport layer.

8.11.  LOCK Method

   The following sections describe the LOCK method, which is used to
   take out a lock of any access type and to refresh an existing lock.
   These sections on the LOCK method describe only those semantics that
   are specific to the LOCK method and are independent of the access
   type of the lock being requested.

   Any resource which supports the LOCK method MUST, at minimum, support
   the XML request and response formats defined herein.



Dusseault                 Expires July 3, 2006                 [Page 58]

Internet-Draft                   WebDAV                    December 2005


   A LOCK method invocation to an unlocked resource creates a lock on
   the resource identified by the Request-URI, which becomes the root of
   the lock.  Lock method requests to create a new lock MUST have a XML
   request body which contains an owner XML element and other
   information for this lock request.  The server MUST preserve the
   information provided by the client in the 'owner' field when the lock
   information is requested.  The LOCK request MAY have a Timeout
   header.

   Clients MUST assume that locks may arbitrarily disappear at any time,
   regardless of the value given in the Timeout header.  The Timeout
   header only indicates the behavior of the server if extraordinary
   circumstances do not occur.  For example, a sufficiently privileged
   user may remove a lock at any time or the system may crash in such a
   way that it loses the record of the lock's existence.

   When a new lock is created, the LOCK response:

   o  MUST contain a body with the value of the DAV:lockdiscovery
      property in a prop XML element.  This MUST contain the full
      information about the lock just granted, while information about
      other (shared) locks is OPTIONAL.

   o  MUST include the Lock-Token response header with the token
      associated with the new lock.

8.11.1.  Refreshing Locks

   A lock is refreshed by sending a LOCK request without a request body
   to the URL of a resource within the scope of the lock.  This request
   MUST specify which lock to refresh by using the 'Lock-Token' header
   with a single lock token (only one lock may be refreshed at a time).
   It MAY contain a Timeout header, which a server MAY accept to change
   the duration remaining on the lock to the new value.  A server MUST
   ignore the Depth header on a LOCK refresh.

   If the resource has other (shared) locks, those locks are unaffected
   by a lock refresh.  Additionally, those locks do not prevent the
   named lock from being refreshed.

   Note that in RFC2518, clients were indicated through the example in
   the text to use the If header to specify what lock to refresh (rather
   than the Lock-Token header).  Servers are encouraged to continue to
   support this as well as the Lock-Token header.

   Note that the Lock-Token header is not be returned in the response
   for a successful refresh LOCK request, but the LOCK response body
   MUST contain the new value for the DAV:lockdiscovery body.



Dusseault                 Expires July 3, 2006                 [Page 59]

Internet-Draft                   WebDAV                    December 2005


8.11.2.  Depth and Locking

   The Depth header may be used with the LOCK method.  Values other than
   0 or infinity MUST NOT be used with the Depth header on a LOCK
   method.  All resources that support the LOCK method MUST support the
   Depth header.

   A Depth header of value 0 means to just lock the resource specified
   by the Request-URI.

   If the Depth header is set to infinity then the resource specified in
   the Request-URI along with all its internal members, all the way down
   the hierarchy, are to be locked.  A successful result MUST return a
   single lock token which represents all the resources that have been
   locked.  If an UNLOCK is successfully executed on this token, all
   associated resources are unlocked.  Hence, partial success is not an
   option.  Either the entire hierarchy is locked or no resources are
   locked.

   If the lock cannot be granted to all resources, the server MUST
   return a Multi-Status response with a 'response' element for at least
   one resource which prevented the lock from being granted, along with
   a suitable status code for that failure (e.g. 403 (Forbidden) or 423
   (Locked)).  Additionally, if the resource causing the failure was not
   the resource requested, then the server MUST include a 'response'
   element for the Request-URI as well, with a 'status' element
   containing 424 Failed Dependency.

   If no Depth header is submitted on a LOCK request then the request
   MUST act as if a "Depth:infinity" had been submitted.

8.11.3.  Locking Unmapped URLs

   A successful LOCK method MUST result in the creation of an empty
   resource which is locked (and which is not a collection), when a
   resource did not previously exist at that URL.  Later on, the lock
   may go away but the empty resource remains.  Empty resources MUST
   then appear in PROPFIND responses including that URL in the response
   scope.  A server MUST respond successfully to a GET request to an
   empty resource, either by using a 204 No Content response, or by
   using 200 OK with a Content-Length header indicating zero length and
   no Content-Type.

8.11.4.  Lock Compatibility Table

   The table below describes the behavior that occurs when a lock
   request is made on a resource.




Dusseault                 Expires July 3, 2006                 [Page 60]

Internet-Draft                   WebDAV                    December 2005


     +--------------------------+----------------+-------------------+
     | Current State            | Shared Lock OK | Exclusive Lock OK |
     +--------------------------+----------------+-------------------+
     | None                     | True           | True              |
     |                          |                |                   |
     | Shared Lock              | True           | False             |
     |                          |                |                   |
     | Exclusive Lock           | False          | False*            |
     +--------------------------+----------------+-------------------+

   Legend: True = lock may be granted.  False = lock MUST NOT be
   granted. *=It is illegal for a principal to request the same lock
   twice.

   The current lock state of a resource is given in the leftmost column,
   and lock requests are listed in the first row.  The intersection of a
   row and column gives the result of a lock request.  For example, if a
   shared lock is held on a resource, and an exclusive lock is
   requested, the table entry is "false", indicating the lock must not
   be granted.

8.11.5.  LOCK Responses

   In addition to the general status codes possible, the following
   status codes have specific applicability to LOCK:

   200 (OK) - The LOCK request succeeded and the value of the DAV:
   lockdiscovery property is included in the response body.

   201 (Created) - The LOCK request was to an unmapped URL, the request
   succeeded and resulted in the creation of a new resource, and the
   value of the DAV:lockdiscovery property is included in the response
   body.

   409 (Conflict) - A resource cannot be created at the destination
   until one or more intermediate collections have been created.  The
   server MUST NOT create those intermediate collections automatically.

   423 (Locked) - The resource is locked already.

   400 (Bad Request), with 'lock-token-matches-request-uri' precondition
   code - The LOCK request was made with a Lock-Token header, indicating
   that the client wishes to refresh the given lock.  However, the
   Request-URI did not fall within the scope of the lock identified by
   the token.  The lock may have a scope that does not include the
   Request-URI, or the lock could have disappeared, or the token may be
   invalid.




Dusseault                 Expires July 3, 2006                 [Page 61]

Internet-Draft                   WebDAV                    December 2005


8.11.6.  Example - Simple Lock Request

   >>Request

     LOCK /workspace/webdav/proposal.doc HTTP/1.1
     Host: example.com
     Timeout: Infinite, Second-4100000000
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx
     Authorization: Digest username="ejw",
       realm="ejw@example.com", nonce="...",
       uri="/workspace/webdav/proposal.doc",
       response="...", opaque="..."

     <?xml version="1.0" encoding="utf-8" ?>
     <D:lockinfo xmlns:D='DAV:'>
       <D:lockscope><D:exclusive/></D:lockscope>
       <D:locktype><D:write/></D:locktype>
       <D:owner>
         <D:href>http://www.ics.uci.edu/~ejw/contact.html</D:href>
       </D:owner>
     </D:lockinfo>





























Dusseault                 Expires July 3, 2006                 [Page 62]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 200 OK
     Lock-Token: <urn:uuid:e71d4fae-5dec-22d6-fea5-00a0c91e6be4>
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:prop xmlns:D="DAV:">
       <D:lockdiscovery>
         <D:activelock>
           <D:locktype><D:write/></D:locktype>
           <D:lockscope><D:exclusive/></D:lockscope>
           <D:depth>infinity</D:depth>
           <D:owner>
             <D:href>http://www.ics.uci.edu/~ejw/contact.html</D:href>
           </D:owner>
           <D:timeout>Second-604800</D:timeout>
           <D:locktoken>
             <D:href
             >urn:uuid:e71d4fae-5dec-22d6-fea5-00a0c91e6be4</D:href>
           </D:locktoken>
           <D:lockroot>
             <D:href
             >http://example.com/workspace/webdav/proposal.doc</D:href>
           </D:lockroot>
         </D:activelock>
       </D:lockdiscovery>
     </D:prop>


   This example shows the successful creation of an exclusive write lock
   on resource http://example.com/workspace/webdav/proposal.doc.  The
   resource http://www.ics.uci.edu/~ejw/contact.html contains contact
   information for the owner of the lock.  The server has an activity-
   based timeout policy in place on this resource, which causes the lock
   to automatically be removed after 1 week (604800 seconds).  Note that
   the nonce, response, and opaque fields have not been calculated in
   the Authorization request header.












Dusseault                 Expires July 3, 2006                 [Page 63]

Internet-Draft                   WebDAV                    December 2005


8.11.7.  Example - Refreshing a Write Lock

   >>Request

     LOCK /workspace/webdav/proposal.doc HTTP/1.1
     Host: example.com
     Timeout: Infinite, Second-4100000000
     Lock-Token: <urn:uuid:e71d4fae-5dec-22d6-fea5-00a0c91e6be4>
     Authorization: Digest username="ejw",
       realm="ejw@example.com", nonce="...",
       uri="/workspace/webdav/proposal.doc",
       response="...", opaque="..."

   >>Response

     HTTP/1.1 200 OK
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:prop xmlns:D="DAV:">
       <D:lockdiscovery>
         <D:activelock>
           <D:locktype><D:write/></D:locktype>
           <D:lockscope><D:exclusive/></D:lockscope>
           <D:depth>infinity</D:depth>
           <D:owner>
             <D:href>http://www.ics.uci.edu/~ejw/contact.html</D:href>
           </D:owner>
           <D:timeout>Second-604800</D:timeout>
           <D:locktoken>
             <D:href
             >urn:uuid:e71d4fae-5dec-22d6-fea5-00a0c91e6be4</D:href>
           </D:locktoken>
           <D:lockroot>
             <D:href
             >http://example.com/workspace/webdav/proposal.doc</D:href>
           </D:lockroot>
         </D:activelock>
       </D:lockdiscovery>
     </D:prop>


   This request would refresh the lock, attempting to reset the timeout
   to the new value specified in the timeout header.  Notice that the
   client asked for an infinite time out but the server choose to ignore
   the request.  In this example, the nonce, response, and opaque fields
   have not been calculated in the Authorization request header.



Dusseault                 Expires July 3, 2006                 [Page 64]

Internet-Draft                   WebDAV                    December 2005


8.11.8.  Example - Multi-Resource Lock Request

   >>Request

     LOCK /webdav/ HTTP/1.1
     Host: example.com
     Timeout: Infinite, Second-4100000000
     Depth: infinity
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx
     Authorization: Digest username="ejw",
       realm="ejw@example.com", nonce="...",
       uri="/workspace/webdav/proposal.doc",
       response="...", opaque="..."

     <?xml version="1.0" encoding="utf-8" ?>
     <D:lockinfo xmlns:D="DAV:">
       <D:locktype><D:write/></D:locktype>
       <D:lockscope><D:exclusive/></D:lockscope>
       <D:owner>
         <D:href>http://www.ics.uci.edu/~ejw/contact.html</D:href>
       </D:owner>
     </D:lockinfo>

   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:multistatus xmlns:D="DAV:">
       <D:response>
         <D:href>http://example.com/webdav/secret</D:href>
         <D:status>HTTP/1.1 403 Forbidden</D:status>
       </D:response>
       <D:response>
         <D:href>http://example.com/webdav/</D:href>
         <D:status>HTTP/1.1 424 Failed Dependency</D:status>
       </D:response>
     </D:multistatus>


   This example shows a request for an exclusive write lock on a
   collection and all its children.  In this request, the client has
   specified that it desires an infinite length lock, if available,
   otherwise a timeout of 4.1 billion seconds, if available.  The
   request entity body contains the contact information for the



Dusseault                 Expires July 3, 2006                 [Page 65]

Internet-Draft                   WebDAV                    December 2005


   principal taking out the lock, in this case a web page URL.

   The error is a 403 (Forbidden) response on the resource
   http://example.com/webdav/secret.  Because this resource could not be
   locked, none of the resources were locked.  Note also that the a
   'response' element for the Request-URI itself has been included as
   required.

   In this example, the nonce, response, and opaque fields have not been
   calculated in the Authorization request header.

8.12.  UNLOCK Method

   The UNLOCK method removes the lock identified by the lock token in
   the Lock-Token request header.  The Request-URI MUST identify a
   resource within the scope of the lock.

   Note that use of Lock-Token header to provide the lock token is not
   consistent with other state-changing methods which all require an If
   header with the lock token.  Thus, the If header is not needed to
   provide the lock token.  Naturally when the If header is present it
   has its normal meaning as a conditional header.

   For a successful response to this method, the server MUST remove the
   lock from the resource identified by the Request-URI and from all
   other resources included in the lock.

   If all resources which have been locked under the submitted lock
   token can not be unlocked then the UNLOCK request MUST fail.

   A successful response to an UNLOCK method does not mean that the
   resource is necessarily unlocked.  It means that the specific lock
   corresponding to the specified token no longer exists.

   Any DAV compliant resource which supports the LOCK method MUST
   support the UNLOCK method.

8.12.1.  Status Codes

   In addition to the general status codes possible, the following
   status codes have specific applicability to UNLOCK:

   204 (No Content) - Normal success response (rather than 200 OK, since
   200 OK would imply a response body, and an UNLOCK success response
   does not normally contain a body)

   400 (Bad Request) - No lock token was provided (see 'lock-token-
   present' precondition), or request was made to a Request-URI that was



Dusseault                 Expires July 3, 2006                 [Page 66]

Internet-Draft                   WebDAV                    December 2005


   not within the scope of the lock (see 'lock-token-matches-request-
   uri' precondition).

   403 (Forbidden) - The currently authenticated principal does not have
   permission to remove the lock.

   409 (Conflict) - The resource was not locked and thus could not be
   unlocked.

8.12.2.  Example - UNLOCK

   >>Request

     UNLOCK /workspace/webdav/info.doc HTTP/1.1
     Host: example.com
     Lock-Token: <urn:uuid:a515cfa4-5da4-22e1-f5b5-00a0451e6bf7>
     Authorization: Digest username="ejw"
       realm="ejw@example.com", nonce="...",
       uri="/workspace/webdav/proposal.doc",
       response="...", opaque="..."

   >>Response

     HTTP/1.1 204 No Content

   In this example, the lock identified by the lock token
   "urn:uuid:a515cfa4-5da4-22e1-f5b5-00a0451e6bf7" is successfully
   removed from the resource
   http://example.com/workspace/webdav/info.doc.  If this lock included
   more than just one resource, the lock is removed from all resources
   included in the lock.  The 204 (No Content) status code is used
   instead of 200 (OK) because there is no response entity body.

   In this example, the nonce, response, and opaque fields have not been
   calculated in the Authorization request header.
















Dusseault                 Expires July 3, 2006                 [Page 67]

Internet-Draft                   WebDAV                    December 2005


9.  HTTP Headers for Distributed Authoring

   All DAV headers follow the same basic formatting rules as HTTP
   headers.  This includes rules like line continuation and how to
   combine (or separate) multiple instances of the same header using
   commas.  WebDAV adds two new conditional headers to the set defined
   in HTTP: the If and Overwrite headers.

9.1.  DAV Header

      DAV              = "DAV" ":" #( compliance-class )
      compliance-class = ( "1" | "2" | "bis" | extend )
      extend           = Coded-URL | token
      Coded-URL        = "<" absolute-URI ">"
                          ; No LWS allowed in Coded-URL
                          ; absolute-URI is defined in RFC3986

   This general-header appearing in the response indicates that the
   resource supports the DAV schema and protocol as specified.  All DAV
   compliant resources MUST return the DAV header with compliance-class
   "1" on all OPTIONS responses.

   The value is a comma-separated list of all compliance class
   identifiers that the resource supports.  Class identifiers may be
   Coded-URLs or tokens (as defined by [RFC2616]).  Identifiers can
   appear in any order.  Identifiers that are standardized through the
   IETF RFC process are tokens, but other identifiers SHOULD be Coded-
   URLs to encourage uniqueness.

   A resource must show class 1 compliance if it shows class 2 or "bis"
   compliance.  In general, support for one compliance class does not
   entail support for any other.  Please refer to section 16 for more
   details on compliance classes defined in this specification.

   This header must also appear on responses to OPTIONS requests to the
   special '*' Request-URI as defined in HTTP/1.1.  In this case it
   means that the repository supports the named features in at least
   some internal URL namespaces.

   As a request header, this header allows the client to advertise
   compliance with named features when the server needs that
   information.  Clients SHOULD NOT send this header unless a standards
   track specification requires it.  Any extension that makes use of
   this as a request header will need to carefully consider caching
   implications.

9.2.  Depth Header




Dusseault                 Expires July 3, 2006                 [Page 68]

Internet-Draft                   WebDAV                    December 2005


      Depth = "Depth" ":" ("0" | "1" | "infinity")

   The Depth request header is used with methods executed on resources
   which could potentially have internal members to indicate whether the
   method is to be applied only to the resource ("Depth: 0"), to the
   resource and its immediate children, ("Depth: 1"), or the resource
   and all its progeny ("Depth: infinity").

   The Depth header is only supported if a method's definition
   explicitly provides for such support.

   The following rules are the default behavior for any method that
   supports the Depth header.  A method may override these defaults by
   defining different behavior in its definition.

   Methods which support the Depth header may choose not to support all
   of the header's values and may define, on a case by case basis, the
   behavior of the method if a Depth header is not present.  For
   example, the MOVE method only supports "Depth: infinity" and if a
   Depth header is not present will act as if a "Depth: infinity" header
   had been applied.

   Clients MUST NOT rely upon methods executing on members of their
   hierarchies in any particular order or on the execution being atomic
   unless the particular method explicitly provides such guarantees.

   Upon execution, a method with a Depth header will perform as much of
   its assigned task as possible and then return a response specifying
   what it was able to accomplish and what it failed to do.

   So, for example, an attempt to COPY a hierarchy may result in some of
   the members being copied and some not.

   Any headers on a method that has a defined interaction with the Depth
   header MUST be applied to all resources in the scope of the method
   except where alternative behavior is explicitly defined.  For
   example, an If-Match header will have its value applied against every
   resource in the method's scope and will cause the method to fail if
   the header fails to match.

   If a resource, source or destination, within the scope of the method
   with a Depth header is locked in such a way as to prevent the
   successful execution of the method, then the lock token for that
   resource MUST be submitted with the request in the If request header.

   The Depth header only specifies the behavior of the method with
   regards to internal children.  If a resource does not have internal
   children then the Depth header MUST be ignored.



Dusseault                 Expires July 3, 2006                 [Page 69]

Internet-Draft                   WebDAV                    December 2005


   Please note, however, that it is always an error to submit a value
   for the Depth header that is not allowed by the method's definition.
   Thus submitting a "Depth: 1" on a COPY, even if the resource does not
   have internal members, will result in a 400 (Bad Request).  The
   method should fail not because the resource doesn't have internal
   members, but because of the illegal value in the header.

9.3.  Destination Header

      Destination = "Destination" ":" ( absolute-URI )

   The Destination request header specifies the URI which identifies a
   destination resource for methods such as COPY and MOVE, which take
   two URIs as parameters.  Note that the absolute-URI production is
   defined in [RFC3986].

   If the Destination value is an absolute URI, it may name a different
   server (or different port or scheme).  If the source server cannot
   attempt a copy to the remote server, it MUST fail the request with a
   502 (Bad Gateway) response.

9.4.  If Header

      If = "If" ":" ( 1*No-tag-list | 1*Tagged-list)
      No-tag-list = List
      Tagged-list = Resource 1*List
      Resource = Coded-URL
      List = "(" 1*(["Not"](State-token | "[" entity-tag "]")) ")"
           ; No LWS allowed between "[", entity-tag and "]"
      State-token = Coded-URL

   The If request header is intended to have similar functionality to
   the If-Match header defined in section 14.24 of [RFC2616].  However
   the If header is intended for use with any URI which represents state
   information, referred to as a state token, about a resource as well
   as ETags.  A typical example of a state token is a lock token, and
   lock tokens are the only state tokens defined in this specification.
   The <DAV:no-lock> state token is an example of a state token that
   will never match an actual valid lock token.  The purpose of this is
   described in Section 9.4.4.

   The If header's purpose is to describe a series of state lists.  If
   the state of the resource to which the header is applied does not
   match any of the specified state lists then the request MUST fail
   with a 412 (Precondition Failed).  If one of the described state
   lists matches the state of the resource then the request may succeed.

   The server MUST do authorization checks before checking this or any



Dusseault                 Expires July 3, 2006                 [Page 70]

Internet-Draft                   WebDAV                    December 2005


   conditional header.  Assuming no other errors, the server MUST parse
   the If header when it appears on any request, evaluate all the
   clauses, and if the conditional evaluates to false, fail as described
   above.

9.4.1.  No-tag-list Production

   The No-tag-list production describes a series of state tokens and
   ETags.  If multiple No-tag-list productions are used then one only
   needs to match the state of the resource for the method to be allowed
   to continue.  All untagged tokens apply to the resource identified in
   the Request-URI.

   Example - no-tag-list production

      If: (<urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2>
             ["I am an ETag"]) (["I am another ETag"])

   The previous header would require that the resource identified in the
   Request-URI be locked with the specified lock token and in the state
   identified by the "I am an ETag" ETag or in the state identified by
   the second ETag "I am another ETag".  To put the matter more plainly
   one can think of the previous If header as being in the form (or (and
   <urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2> ["I am an ETag"])
   (and ["I am another ETag"])).

9.4.2.  Tagged-list Production

   The tagged-list production may be used instead of the no-tag-list
   production, in order to scope each token to a specific resource.
   That is, it specifies that the lists following the resource
   specification only apply to the specified resource.  The scope of the
   resource production begins with the list production immediately
   following the resource production and ends with the next resource
   production, if any.  All clauses must be evaluated.  If the state of
   the resource named in the tag does not match any of the associated
   state lists then the request MUST fail with a 412 (Precondition
   Failed).

   The same URI MUST NOT appear more than once in a resource production
   in an If header.










Dusseault                 Expires July 3, 2006                 [Page 71]

Internet-Draft                   WebDAV                    December 2005


9.4.3.  Example - Tagged List If header in COPY

   >>Request

     COPY /resource1 HTTP/1.1
     Host: www.example.com
     Destination: http://www.example.com/resource2
     If: <http://www.example.com/resource1>
           (<urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2>
           [W/"A weak ETag"]) (["strong ETag"])
         <http://www.example.com/random>
           (["another strong ETag"])

   In this example http://www.example.com/resource1 is being copied to
   http://www.example.com/resource2.  When the method is first applied
   to http://www.example.com/resource1, resource1 must be in the state
   specified by "(<urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2> [W/"A
   weak ETag"]) (["strong ETag"])", that is, it either must be locked
   with a lock token of "urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2"
   and have a weak entity tag W/"A weak ETag" or it must have a strong
   entity tag "strong ETag".

   That is the only success condition since the resource
   http://www.example.com/random never has the method applied to it (the
   only other resource listed in the If header) and
   http://www.example.com/resource2 is not listed in the If header.

9.4.4.  Not Production

   Every state token or ETag is either current, and hence describes the
   state of a resource, or is not current, and does not describe the
   state of a resource.  The boolean operation of matching a state token
   or ETag to the current state of a resource thus resolves to a true or
   false value.  The "Not" production is used to reverse that value.
   The scope of the not production is the state-token or entity-tag
   immediately following it.

        If: (Not <urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2>
             <urn:uuid:58f202ac-22cf-11d1-b12d-002035b29092>)

   When submitted with a request, this If header requires that all
   operand resources must not be locked with
   urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2 and must be locked with
   urn:uuid:58f202ac-22cf-11d1-b12d-002035b29092.

   The Not production is particularly useful with a state token known
   not to ever identify a lock, such as the "<DAV:no-lock>" state token.
   The clause "Not <DAV:no-lock>" MUST evaluate to true.  Thus, any "OR"



Dusseault                 Expires July 3, 2006                 [Page 72]

Internet-Draft                   WebDAV                    December 2005


   statement containing the clause "Not <DAV:no-lock>" MUST also
   evaluate to true.

9.4.5.  Matching Function

   When performing If header processing, the definition of a matching
   state token or entity tag is as follows.

   Identifying a resource: The resource is identified by the URI along
   with the token, in tagged list production, or by the Request-URI in
   untagged list production.

   Matching entity tag: Where the entity tag matches an entity tag
   associated with the identified resource.

   Matching state token: Where there is an exact match between the state
   token in the If header and any state token on the identified
   resource.  A lock state token is considered to match if the resource
   is anywhere in the scope of the lock.

   Example - Matching lock tokens with collection locks

    DELETE /specs/rfc2518.txt HTTP/1.1
    Host: www.example.com
    If: <http://www.example.com/specs/>
          (<urn:uuid:181d4fae-7d8c-11d0-a765-00a0c91e6bf2>)

   For this example, the lock token must be compared to the identified
   resource, which is the 'specs' collection identified by the URL in
   the tagged list production.  If the 'specs' collection is not locked
   or has a lock with a different token, the request MUST fail.  If the
   'specs' collection is locked (depth infinity) with that lock token,
   then this request could succeed, both because the If header evaluates
   to true, and because the lock token for the lock affecting the
   affected resource has been provided.  Alternatively, a request where
   the 'rfc2518.txt' URL is associated with the lock token in the If
   header could also succeed.

9.4.6.  If Header and Non-DAV Aware Proxies

   Non-DAV aware proxies will not honor the If header, since they will
   not understand the If header, and HTTP requires non-understood
   headers to be ignored.  When communicating with HTTP/1.1 proxies, the
   "Cache-Control: no-cache" request header MUST be used so as to
   prevent the proxy from improperly trying to service the request from
   its cache.  When dealing with HTTP/1.0 proxies the "Pragma: no-cache"
   request header MUST be used for the same reason.




Dusseault                 Expires July 3, 2006                 [Page 73]

Internet-Draft                   WebDAV                    December 2005


9.5.  Lock-Token Header

      Lock-Token = "Lock-Token" ":" Coded-URL

   The Lock-Token request header is used with the UNLOCK method to
   identify the lock to be removed.  The lock token in the Lock-Token
   request header MUST identify a lock that contains the resource
   identified by Request-URI as a member.

   The Lock-Token response header is used with the LOCK method to
   indicate the lock token created as a result of a successful LOCK
   request to create a new lock.

9.6.  Overwrite Header

      Overwrite = "Overwrite" ":" ("T" | "F")

   The Overwrite request header specifies whether the server should
   overwrite a resource mapped to the destination URL during a COPY or
   MOVE.  A value of "F" states that the server must not perform the
   COPY or MOVE operation if the state of the destination URL does map
   to a resource.  If the overwrite header is not included in a COPY or
   MOVE request then the resource MUST treat the request as if it has an
   overwrite header of value "T".  While the Overwrite header appears to
   duplicate the functionality of the If-Match: * header of HTTP/1.1,
   If-Match applies only to the Request-URI, and not to the Destination
   of a COPY or MOVE.

   If a COPY or MOVE is not performed due to the value of the Overwrite
   header, the method MUST fail with a 412 (Precondition Failed) status
   code.  The server MUST do authorization checks before checking this
   or any conditional header.

   All DAV compliant resources MUST support the Overwrite header.

9.7.  Timeout Request Header

      TimeOut = "Timeout" ":" 1#TimeType
      TimeType = ("Second-" DAVTimeOutVal | "Infinite")
                 ; No LWS allowed within TimeType
      DAVTimeOutVal = 1*DIGIT

   Clients may include Timeout request headers in their LOCK requests.
   However, the server is not required to honor or even consider these
   requests.  Clients MUST NOT submit a Timeout request header with any
   method other than a LOCK method.

   Timeout response values MUST use a Second value or Infinite.



Dusseault                 Expires July 3, 2006                 [Page 74]

Internet-Draft                   WebDAV                    December 2005


   The "Second" TimeType specifies the number of seconds that will
   elapse between granting of the lock at the server, and the automatic
   removal of the lock.  The timeout value for TimeType "Second" MUST
   NOT be greater than 2^32-1.

   The timeout counter MUST be restarted if a refresh LOCK request is
   successful.  The timeout counter SHOULD NOT be restarted at any other
   time.

   If the timeout expires then the lock may be lost.  Specifically, if
   the server wishes to harvest the lock upon time-out, the server
   SHOULD act as if an UNLOCK method was executed by the server on the
   resource using the lock token of the timed-out lock, performed with
   its override authority.  Thus logs should be updated with the
   disposition of the lock, notifications should be sent, etc., just as
   they would be for an UNLOCK request.

   Servers are advised to pay close attention to the values submitted by
   clients, as they will be indicative of the type of activity the
   client intends to perform.  For example, an applet running in a
   browser may need to lock a resource, but because of the instability
   of the environment within which the applet is running, the applet may
   be turned off without warning.  As a result, the applet is likely to
   ask for a relatively small timeout value so that if the applet dies,
   the lock can be quickly harvested.  However, a document management
   system is likely to ask for an extremely long timeout because its
   user may be planning on going off-line.

   A client MUST NOT assume that just because the time-out has expired
   the lock has been lost.  Likewise, a client MUST NOT assume that just
   because the time-out has not expired, the lock still exists (and for
   this reason, clients are strongly advised to use ETags as well).



















Dusseault                 Expires July 3, 2006                 [Page 75]

Internet-Draft                   WebDAV                    December 2005


10.  Status Code Extensions to HTTP/1.1

   The following status codes are added to those defined in HTTP/1.1
   [RFC2616].

10.1.  207 Multi-Status

   The 207 (Multi-Status) status code provides status for multiple
   independent operations (see Section 12 for more information).

10.2.  422 Unprocessable Entity

   The 422 (Unprocessable Entity) status code means the server
   understands the content type of the request entity (hence a
   415(Unsupported Media Type) status code is inappropriate), and the
   syntax of the request entity is correct (thus a 400 (Bad Request)
   status code is inappropriate) but was unable to process the contained
   instructions.  For example, this error condition may occur if an XML
   request body contains well-formed (i.e., syntactically correct), but
   semantically erroneous XML instructions.

10.3.  423 Locked

   The 423 (Locked) status code means the source or destination resource
   of a method is locked.  This response SHOULD contain the 'lock-token-
   present' precondition element and corresponding 'href' in the error
   body.

10.4.  424 Failed Dependency

   The 424 (Failed Dependency) status code means that the method could
   not be performed on the resource because the requested action
   depended on another action and that action failed.  For example, if a
   command in a PROPPATCH method fails then, at minimum, the rest of the
   commands will also fail with 424 (Failed Dependency).

10.5.  507 Insufficient Storage

   The 507 (Insufficient Storage) status code means the method could not
   be performed on the resource because the server is unable to store
   the representation needed to successfully complete the request.  This
   condition is considered to be temporary.  If the request which
   received this status code was the result of a user action, the
   request MUST NOT be repeated until it is requested by a separate user
   action.






Dusseault                 Expires July 3, 2006                 [Page 76]

Internet-Draft                   WebDAV                    December 2005


11.  Use of HTTP Status Codes

   These HTTP codes are not redefined, but their use is somewhat
   extended by WebDAV methods and requirements.  In general, many HTTP
   status codes can be used in response to any request, not just in
   cases described in this document.  Note also that WebDAV servers are
   known to use 300-level redirect responses (and early interoperability
   tests found clients unprepared to see those responses).  A 300-level
   request MUST NOT be used when the server has created a new resource
   in response to the request.

11.1.  412 Precondition Failed

   Any request can contain a conditional header defined in HTTP (If-
   Match, If-Modified-Since, etc.) or the "If" or "Overwrite"
   conditional headers defined in this specification.  If the request
   contains a conditional header, and if that condition fails to hold,
   then this error code MUST be returned unless some other error is
   returned.  On the other hand, if the client did not include a
   conditional header in the request, then the server MUST NOT use this
   error.

11.2.  414 Request-URI Too Long

   This status code is used in HTTP 1.1 only for Request-URIs, because
   full URIs aren't used in other headers.  WebDAV specifies full URLs
   in other headers, therefore this error MAY be used if the URI is too
   long in other locations as well.























Dusseault                 Expires July 3, 2006                 [Page 77]

Internet-Draft                   WebDAV                    December 2005


12.  Multi-Status Response

   A Multi-Status response contains one 'response' element for each
   resource in the scope of the request (in no required order) or may be
   empty if no resources match the request.  The default 207 (Multi-
   Status) response body is a text/xml or application/xml HTTP entity
   that contains a single XML element called 'multistatus', which
   contains a set of XML elements called response which contain 200,
   300, 400, and 500 series status codes generated during the method
   invocation. 100 series status codes SHOULD NOT be recorded in a
   'response' XML element.  The 207 status code itself MUST NOT be
   considered a success response, it is only completely successful if
   all 'response' elements inside contain success status codes.

   The body of a 207 Multi-Status response MUST contain a URL associated
   with each specific status code, so that the client can tell whether
   the error occurred with the source resource, destination resource or
   some other resource in the scope of the request.

12.1.  Response headers

   HTTP defines the Location header to indicate a preferred URL for the
   resource that was addressed in the Request-URI (e.g. in response to
   successful PUT requests or in redirect responses).  However, use of
   this header creates ambiguity when there are URLs in the body of the
   response, as with Multi-Status.  Thus, use of the Location header
   with the Multi-Status response is intentionally undefined.

12.2.  URL Handling

   A Multi-Status body contains one or more 'response' elements.  Each
   response element describes a resource, and has an 'href' element
   identifying the resource.  The 'href' element MUST contain an
   absolute URI or relative reference.  It MUST NOT include "." or ".."
   as path elements.

   If a 'href' element contains a relative reference, it MUST be
   resolved against the Request-URI.  A relative reference MUST be an
   absolute path (note that clients are not known to support relative
   paths).

   Identifiers for collections appearing in the results SHOULD end in a
   '/' character.

   If a server allows resource names to include characters that aren't
   legal in HTTP URL paths, these characters must be percent-encoded on
   the wire (see [RFC3986], section 2.1).  For example, it is illegal to
   use a space character or double-quote in a URI.  URIs appearing in



Dusseault                 Expires July 3, 2006                 [Page 78]

Internet-Draft                   WebDAV                    December 2005


   PROPFIND or PROPPATCH XML bodies (or other XML marshalling defined in
   this specification) are still subject to all URI rules, including
   forbidden characters.

12.3.  Handling redirected child resources

   Redirect responses (300-303, 305 and 307) defined in HTTP 1.1
   normally take a Location header to indicate the new URI for the
   single resource redirected from the Request-URI.  Multi-Status
   responses contain many resource addresses, but the original
   definition in RFC2518 did not have any place for the server to
   provide the new URI for redirected resources.  This specification
   does define a 'location' element for this information (see
   Section 13.9).  Servers MUST use this new element with redirect
   responses in Multi-Status.

   Clients encountering redirected resources in Multi-Status MUST NOT
   rely on the 'location' element being present with a new URI.  If the
   element is not present, the client MAY reissue the request to the
   individual redirected resource, because the response to that request
   can be redirected with a Location header containing the new URI.

12.4.  Internal Status Codes

   Section 8.3.1, Section 8.2.2, Section 8.7.1, Section 8.9.3 and
   Section 8.10.2 define various status codes used in Multi-Status
   responses.  This specification does not define the meaning of other
   status codes that could appear in these responses.























Dusseault                 Expires July 3, 2006                 [Page 79]

Internet-Draft                   WebDAV                    December 2005


13.  XML Element Definitions

   In this section, the final line of each section gives the element
   type declaration using the format defined in [XML].  The "Value"
   field, where present, specifies further restrictions on the allowable
   contents of the XML element using BNF (i.e., to further restrict the
   values of a PCDATA element).  The "Extensibility" field discusses how
   the element may be extended in the future (or in existing extensions
   to WebDAV.

   All of the elements defined here may be extended by the addition of
   attributes and child elements not defined in this specification.  All
   elements defined here are in the "DAV:" namespace.

13.1.  activelock XML Element

   Name:  activelock

   Purpose:  Describes a lock on a resource.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.


   <!ELEMENT activelock (lockscope, locktype, depth, owner?, timeout?,
   locktoken?, lockroot)>

13.2.  allprop XML Element

   Name:  allprop

   Purpose:  Specifies that all names and values of dead properties and
      the live properties defined by this document existing on the
      resource are to be returned.

   Extensibility:  Normally empty, but MAY be extended with additional
      child elements or attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT allprop EMPTY >

13.3.  collection XML Element

   Name:  collection







Dusseault                 Expires July 3, 2006                 [Page 80]

Internet-Draft                   WebDAV                    December 2005


   Purpose:  Identifies the associated resource as a collection.  The
      DAV:resourcetype property of a collection resource MUST contain
      this element.  It is normally empty but extensions may add sub-
      elements.

   Extensibility:  MAY be extended with child elements or attributes
      which SHOULD be ignored if not recognized.

   <!ELEMENT collection EMPTY >

13.4.  dead-props XML Element

   Name:  dead-props

   Purpose:  Specifies that all dead properties, names and values,
      should be returned in the response.

   Extensibility:  Normally empty, but MAY be extended with additional
      child elements or attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT dead-props EMPTY >

13.5.  depth XML Element

   Name:  depth

   Purpose:  The value of the Depth header.

   Value:  "0" | "1" | "infinity"

   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT depth (#PCDATA) >

13.6.  error XML Element

   Name:  error

   Purpose:  Error responses, particularly 403 Forbidden and 409
      Conflict, sometimes need more information to indicate what went
      wrong.  When an error response contains a body in WebDAV, the body
      is in XML with the root element 'error'.  The 'error' element
      SHOULD include an XML element with the code of a failed
      precondition or postcondition.





Dusseault                 Expires July 3, 2006                 [Page 81]

Internet-Draft                   WebDAV                    December 2005


   Description:  Contains any XML element

   Extensibility:  Fully extensible with additional child elements,
      attributes or text (possibly mixed content).  Unrecognized
      information items SHOULD be ignored if not recognized.

   <!ELEMENT error ANY >

13.7.  exclusive XML Element

   Name:  exclusive

   Purpose:  Specifies an exclusive lock

   Extensibility:  Normally empty, but MAY be extended with additional
      child elements or attributes which SHOULD be ignored if not
      recognized.


   <!ELEMENT exclusive EMPTY >


13.8.  href XML Element

   Name:  href

   Purpose:  Identifies the content of the element as a URI or a
      relative reference.  There may be limits on the value of 'href'
      depending on the context of its use.  Refer to the specification
      text where 'href' is used to see what limitations apply in each
      case.

   Value:  URI-reference (See section 4.1 of [RFC3986])

   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored if not recognized.


      <!ELEMENT href (#PCDATA)>

13.9.  location XML Element

   Name:  location

   Purpose:  HTTP defines the "Location" header (see [RFC2616], section
      14.30) for use with some status codes (such as 201 and the 300
      series codes).  When these codes are used inside a Multi-Status
      response, the 'location' element can be used to provide the



Dusseault                 Expires July 3, 2006                 [Page 82]

Internet-Draft                   WebDAV                    December 2005


      accompanying 'Location' header.

   Description:  Contains a single href element with the same value that
      would be used in a Location header.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.


      <!ELEMENT location (href)>

13.10.  lockentry XML Element

   Name:  lockentry

   Purpose:  Defines the types of locks that can be used with the
      resource.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT lockentry (lockscope, locktype) >

13.11.  lockinfo XML Element

   Name:  lockinfo

   Purpose:  The 'lockinfo' XML element is used with a LOCK method to
      specify the type of lock the client wishes to have created.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.


   <!ELEMENT lockinfo (lockscope, locktype, owner?)  >

13.12.  lockroot XML Element

   Name:  lockroot

   Purpose:  Contains the root URL of the lock, which is the URL through
      which the resource was addressed in the LOCK request.

   Description:  The href contains a HTTP URL with the address of the
      root of the lock.  The server SHOULD include this in all DAV:
      lockdiscovery property values and the response to LOCK requests.





Dusseault                 Expires July 3, 2006                 [Page 83]

Internet-Draft                   WebDAV                    December 2005


   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT lockroot (href) >

13.13.  lockscope XML Element

   Name:  lockscope

   Purpose:  Specifies whether a lock is an exclusive lock, or a shared
      lock.

   Extensibility:  SHOULD NOT be extended with child elements.  MAY be
      extended with attributes which SHOULD be ignored.


     <!ELEMENT lockscope (exclusive | shared) >


13.14.  locktoken XML Element

   Name:  locktoken

   Purpose:  The lock token associated with a lock.

   Description:  The href contains a single lock token URI which refers
      to the lock.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT locktoken (href) >

13.15.  locktype XML Element

   Name:  locktype

   Purpose:  Specifies the access type of a lock.  At present, this
      specification only defines one lock type, the write lock.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.


   <!ELEMENT locktype (write) >






Dusseault                 Expires July 3, 2006                 [Page 84]

Internet-Draft                   WebDAV                    December 2005


13.16.  multistatus XML Element

   Name:  multistatus

   Purpose:  Contains multiple response messages.

   Description The 'responsedescription' element at the top level is
      used to provide a general message describing the overarching
      nature of the response.  If this value is available an application
      may use it instead of presenting the individual response
      descriptions contained within the responses.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.


   <!ELEMENT multistatus (response+, responsedescription?)  >


13.17.  owner XML Element

   Name:  owner

   Purpose:  Provides information about the principal taking out a lock.

   Description Provides information sufficient for either directly
      contacting a principal (such as a telephone number or Email URI),
      or for discovering the principal (such as the URL of a homepage)
      who owns a lock.  This information is provided by the client, and
      may only be altered by the server if the owner value provided by
      the client is empty.

   Extensibility MAY be extended with child elements, mixed content,
      text content or attributes.  Structured content, for example one
      or more 'href' child elements containing URIs of any kind, is
      RECOMMENDED.

   <!ELEMENT owner ANY >

13.18.  prop XML element

   Name:  prop

   Purpose:  Contains properties related to a resource.







Dusseault                 Expires July 3, 2006                 [Page 85]

Internet-Draft                   WebDAV                    December 2005


   Description A generic container for properties defined on resources.
      All elements inside a 'prop' XML element MUST define properties
      related to the resource.  No other elements may be used inside of
      a 'prop' element.

   Extensibility MAY be extended with attributes which SHOULD be ignored
      if not recognized.  Any child element of this element must be
      considered to be a property name, however these are not restricted
      to the property names defined in this document or other standards.

   <!ELEMENT prop ANY >

13.19.  propertyupdate XML element

   Name:  propertyupdate

   Purpose:  Contains a request to alter the properties on a resource.

   Description:  This XML element is a container for the information
      required to modify the properties on the resource.  This XML
      element is multi-valued.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT propertyupdate (remove | set)+ >

13.20.  propfind XML Element

   Name:  propfind

   Purpose:  Specifies the properties to be returned from a PROPFIND
      method.  Four special elements are specified for use with
      'propfind': 'prop', 'dead-props', 'allprop' and 'propname'.  If
      'prop' is used inside 'propfind' it MUST NOT contain property
      values.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized, as long as
      it still contains one of the required elements.

   <!ELEMENT propfind ( propname | allprop | (prop, dead-props?) ) >

13.21.  propname XML Element







Dusseault                 Expires July 3, 2006                 [Page 86]

Internet-Draft                   WebDAV                    December 2005


   Name:  propname

   Purpose:  Specifies that only a list of property names on the
      resource is to be returned.

   Extensibility:  Normally empty, but MAY be extended with additional
      child elements or attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT propname EMPTY >

13.22.  propstat XML Element

   Name:  propstat

   Purpose:  Groups together a prop and status element that is
      associated with a particular 'href' element.

   Description:  The propstat XML element MUST contain one prop XML
      element and one status XML element.  The contents of the prop XML
      element MUST only list the names of properties to which the result
      in the status element applies.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT propstat (prop, status, responsedescription?) >

13.23.  remove XML element

   Name:  remove

   Purpose:  Lists the DAV properties to be removed from a resource.

   Description:  Remove instructs that the properties specified in prop
      should be removed.  Specifying the removal of a property that does
      not exist is not an error.  All the XML elements in a 'prop' XML
      element inside of a 'remove' XML element MUST be empty, as only
      the names of properties to be removed are required.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT remove (prop) >

13.24.  response XML Element





Dusseault                 Expires July 3, 2006                 [Page 87]

Internet-Draft                   WebDAV                    December 2005


   Name:  response

   Purpose:  Holds a single response describing the effect of a method
      on resource and/or its properties.

   Description:  The 'href' element contains a HTTP URL pointing to a
      WebDAV resource when used in the 'response' container.  A
      particular 'href' value MUST NOT appear more than once as the
      child of a 'response' XML element under a 'multistatus' XML
      element.  This requirement is necessary in order to keep
      processing costs for a response to linear time.  Essentially, this
      prevents having to search in order to group together all the
      responses by 'href'.  There are, however, no requirements
      regarding ordering based on 'href' values.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.


   <!ELEMENT response (href, ((href*, status)|(propstat+)),
         responsedescription? , location?) >

13.25.  responsedescription XML Element

   Name:  responsedescription

   Purpose:  Contains information about a status response within a
      Multi-Status.

   Description:  This XML element provides either information suitable
      to be presented to a user (PCDATA) or a machine readable error
      code.

   Extensibility:  MAY be extended with additional attributes which
      SHOULD be ignored if not recognized.

   <!ELEMENT responsedescription (#PCDATA | error) >

13.26.  set XML element

   Name:  set

   Purpose:  Lists the DAV property values to be set for a resource.

   Description:  The 'set' XML element MUST contain only a prop XML
      element.  The elements contained by the prop XML element inside
      the 'set' XML element MUST specify the name and value of
      properties that are set on the resource identified by Request-URI.



Dusseault                 Expires July 3, 2006                 [Page 88]

Internet-Draft                   WebDAV                    December 2005


      If a property already exists then its value is replaced.  Language
      tagging information appearing in the scope of the 'prop' element
      (in the "xml:lang" attribute, if present) MUST be persistently
      stored along with the property, and MUST be subsequently
      retrievable using PROPFIND.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT set (prop) >

13.27.  shared XML Element

   Name:  shared

   Purpose:  Specifies a shared lock

   Extensibility:  Normally empty, but MAY be extended with additional
      child elements or attributes which SHOULD be ignored if not
      recognized.


   <!ELEMENT shared EMPTY >


13.28.  status XML Element

   Name:  status

   Purpose:  Holds a single HTTP status-line

   Value:  status-line (status-line defined in Section 6.1 of [RFC2616])

   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT status (#PCDATA) >

13.29.  timeout XML Element

   Name:  timeout

   Purpose:  The number of seconds remaining before a lock expires.

   Value:  TimeType (defined in Section 9.7).






Dusseault                 Expires July 3, 2006                 [Page 89]

Internet-Draft                   WebDAV                    December 2005


   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.


      <!ELEMENT timeout (#PCDATA) >

13.30.  write XML Element

   Name:  write

   Purpose:  Specifies a write lock.

   Extensibility:  Normally empty, but MAY be extended with additional
      child elements or attributes which SHOULD be ignored if not
      recognized.


   <!ELEMENT write EMPTY >

































Dusseault                 Expires July 3, 2006                 [Page 90]

Internet-Draft                   WebDAV                    December 2005


14.  DAV Properties

   For DAV properties, the name of the property is also the same as the
   name of the XML element that contains its value.  In the section
   below, the final line of each section gives the element type
   declaration using the format defined in [XML].  The "Value" field,
   where present, specifies further restrictions on the allowable
   contents of the XML element using BNF (i.e., to further restrict the
   values of a PCDATA element).  Note that a resource may have only one
   value for a property of a given name, so the property may only show
   up once in PROPFIND responses or PROPPATCH requests.

   A protected property is one which cannot be changed with a PROPPATCH
   request.  There may be other requests which would result in a change
   to a protected property (as when a PUT request to an existing
   resource causes DAV:contentlength to change to a new value).  Note
   that a given property could be protected on one type of resource, but
   not protected on another type of resource.

   A computed property is one with a value defined in terms of a
   computation (based on the content and other properties of that
   resource, or even of some other resource).  A computed property is
   always a protected property.

   COPY and MOVE behavior refers to local COPY and MOVE operations.

   For properties defined based on HTTP GET response headers (DAV:get*),
   the value could include LWS as defined in [RFC2616], section 4.2.
   Server implementors SHOULD NOT include extra LWS in these values,
   however client implementors MUST be prepared to handle extra LWS.

14.1.  creationdate Property

   Name:  creationdate

   Purpose:  Records the time and date the resource was created.

   Value:  date-time (defined in [RFC3339], see the ABNF in section
      5.6.)

   Protected:  MAY be protected.  Some servers allow DAV:creationdate to
      be changed to reflect the time the document was created if that is
      more meaningful to the user (rather than the time it was
      uploaded).  Thus, clients SHOULD NOT use this property in
      synchronization logic (use DAV:getetag instead).






Dusseault                 Expires July 3, 2006                 [Page 91]

Internet-Draft                   WebDAV                    December 2005


   COPY/MOVE behaviour:  This property value SHOULD be kept during a
      MOVE operation, but is normally re-initialized when a resource is
      created with a COPY.  It should not be set in a COPY.

   Description:  The DAV:creationdate property SHOULD be defined on all
      DAV compliant resources.  If present, it contains a timestamp of
      the moment when the resource was created.  Servers that are
      incapable of persistently recording the creation date SHOULD
      instead leave it undefined (i.e. report "Not Found")

   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT creationdate (#PCDATA) >

14.2.  displayname Property

   Name:  displayname

   Purpose:  Provides a name for the resource that is suitable for
      presentation to a user.

   Value:  Any text

   Protected:  SHOULD NOT be protected.  Note that servers implementing
      RFC2518 might have made this a protected property as this is a new
      requirement.

   COPY/MOVE behaviour:  This property value SHOULD be preserved in COPY
      and MOVE operations.

   Description:  The DAV:displayname property should be defined on all
      DAV compliant resources.  If present, the property contains a
      description of the resource that is suitable for presentation to a
      user.  This property is defined on the resource, and hence SHOULD
      have the same value independent of the Request-URI used to
      retrieve it (thus computing this property based on the Request-URI
      is deprecated).

   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT displayname (#PCDATA) >

14.3.  getcontentlanguage Property






Dusseault                 Expires July 3, 2006                 [Page 92]

Internet-Draft                   WebDAV                    December 2005


   Name:  getcontentlanguage

   Purpose:  Contains the Content-Language header value (from section
      14.12 of [RFC2616]) as it would be returned by a GET without
      accept headers.

   Value:  language-tag (language-tag is defined in section 3.10 of
      [RFC2616]).

   Protected:  SHOULD NOT be protected, so that clients can reset the
      language.  Note that servers implementing RFC2518 might have made
      this a protected property as this is a new requirement.

   COPY/MOVE behaviour:  This property value SHOULD be preserved in COPY
      and MOVE operations.

   Description:  The DAV:getcontentlanguage property MUST be defined on
      any DAV compliant resource that returns the Content-Language
      header on a GET.

   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getcontentlanguage (#PCDATA) >

14.4.  getcontentlength Property

   Name:  getcontentlength

   Purpose:  Contains the Content-Length header returned by a GET
      without accept headers.

   Value:  See section 14.13 of [RFC2616].

   Protected:  This property is computed, therefore protected.

   Description:  The DAV:getcontentlength property MUST be defined on
      any DAV compliant resource that returns the Content-Length header
      in response to a GET.

   COPY/MOVE behaviour:  This property value is dependent on the size of
      the destination resource, not the value of the property on the
      source resource.

   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getcontentlength (#PCDATA) >



Dusseault                 Expires July 3, 2006                 [Page 93]

Internet-Draft                   WebDAV                    December 2005


14.5.  getcontenttype Property

   Name:  getcontenttype

   Purpose:  Contains the Content-Type header value (from section 14.17
      of [RFC2616]) as it would be returned by a GET without accept
      headers.

   Value:  media-type (defined in section 3.7 of [RFC2616])

   Protected:  SHOULD NOT be protected, so clients may fix this value.
      Note that servers implementing RFC2518 might have made this a
      protected property as this is a new requirement.

   COPY/MOVE behaviour:  This property value SHOULD be preserved in COPY
      and MOVE operations.

   Description:  This property MUST be defined on any DAV compliant
      resource that returns the Content-Type header in response to a
      GET.

   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getcontenttype (#PCDATA) >

14.6.  getetag Property

   Name:  getetag

   Purpose:  Contains the ETag header value (from section 14.19 of
      [RFC2616]) as it would be returned by a GET without accept
      headers.

   Value:  entity-tag (defined in section 3.11 of [RFC2616])

   Protected: MUST be protected because this value is created and
      controlled by the server.

   COPY/MOVE behaviour:  This property value is dependent on the final
      state of the destination resource, not the value of the property
      on the source resource.

   Description:  The getetag property MUST be defined on any DAV
      compliant resource that returns the Etag header.  Refer to RFC2616
      for a complete definition of the semantics of an ETag.  Note that
      changes in properties or lock state MUST not cause a resource's
      ETag to change.



Dusseault                 Expires July 3, 2006                 [Page 94]

Internet-Draft                   WebDAV                    December 2005


   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getetag (#PCDATA) >

14.7.  getlastmodified Property

   Name:  getlastmodified

   Purpose:  Contains the Last-Modified header value (from section 14.29
      of [RFC2616]) as it would be returned by a GET method without
      accept headers.

   Value:  rfc1123-date (defined in section 3.3.1 of [RFC2616])

   Protected:  SHOULD be protected because some clients may rely on the
      value for appropriate caching behavior, or on the value of the
      Last-Modified header to which this property is linked.

   COPY/MOVE behaviour:  This property value is dependent on the last
      modified date of the destination resource, not the value of the
      property on the source resource.  Note that some server
      implementations use the file system date modified value for the
      DAV:getlastmodified value, and this is preserved in a MOVE even
      when the HTTP Last-Modified value SHOULD change.  Thus, clients
      cannot rely on this value for caching and SHOULD use ETags.

   Description:  Note that the last-modified date on a resource SHOULD
      only reflect changes in the body (the GET responses) of the
      resource.  A change in a property only SHOULD NOT cause the last-
      modified date to change, because clients MAY rely on the last-
      modified date to know when to overwrite the existing body.  The
      DAV:getlastmodified property MUST be defined on any DAV compliant
      resource that returns the Last-Modified header in response to a
      GET.

   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getlastmodified (#PCDATA) >

14.8.  lockdiscovery Property

   Name:  lockdiscovery







Dusseault                 Expires July 3, 2006                 [Page 95]

Internet-Draft                   WebDAV                    December 2005


   Purpose:  Describes the active locks on a resource

   Protected:  MUST be protected.  Clients change the list of locks
      through LOCK and UNLOCK, not through PROPPATCH.

   COPY/MOVE behaviour:  The value of this property depends on the lock
      state of the destination, not on the locks of the source resource.
      Recall that locks are not moved in a MOVE operation.

   Description:  Returns a listing of who has a lock, what type of lock
      he has, the timeout type and the time remaining on the timeout,
      and the associated lock token.  If there are no locks, but the
      server supports locks, the property will be present but contain
      zero 'activelock' elements.  If there is one or more lock, an
      'activelock' element appears for each lock on the resource.

   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT lockdiscovery (activelock)* >

14.8.1.  Example - Retrieving the lockdiscovery Property

   >>Request

     PROPFIND /container/ HTTP/1.1
     Host: www.example.com
     Content-Length: xxxx
     Content-Type: application/xml; charset="utf-8"

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propfind xmlns:D='DAV:'>
       <D:prop><D:lockdiscovery/></D:prop>
     </D:propfind>

















Dusseault                 Expires July 3, 2006                 [Page 96]

Internet-Draft                   WebDAV                    December 2005


   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:multistatus xmlns:D='DAV:'>
       <D:response>
         <D:href>http://www.example.com/container/</D:href>
         <D:propstat>
           <D:prop>
             <D:lockdiscovery>
              <D:activelock>
               <D:locktype><D:write/></D:locktype>
               <D:lockscope><D:exclusive/></D:lockscope>
               <D:depth>0</D:depth>
               <D:owner>Jane Smith</D:owner>
               <D:timeout>Infinite</D:timeout>
               <D:locktoken>
                 <D:href
             >urn:uuid:f81de2ad-7f3d-a1b2-4f3c-00a0c91a9d76</D:href>
               </D:locktoken>
               <D:lockroot>
                 <D:href>http://www.example.com/container/</D:href>
               </D:lockroot>
               </D:activelock>
             </D:lockdiscovery>
           </D:prop>
           <D:status>HTTP/1.1 200 OK</D:status>
         </D:propstat>
       </D:response>
     </D:multistatus>

   This resource has a single exclusive write lock on it, with an
   infinite timeout.

14.9.  resourcetype Property

   Name:  resourcetype

   Purpose:  Specifies the nature of the resource.

   Protected:  SHOULD be protected.  Resource type is generally decided
      through the operation creating the resource (MKCOL vs PUT), not by
      PROPPATCH.





Dusseault                 Expires July 3, 2006                 [Page 97]

Internet-Draft                   WebDAV                    December 2005


   COPY/MOVE behaviour:  Generally a COPY/MOVE of a resource results in
      the same type of resource at the destination.

   Description:  MUST be defined on all DAV compliant resources.  Each
      child element identifies a specific type the resource belongs to,
      such as 'collection', which is the only resource type defined by
      this specification (see Section 13.3).  If the element contains
      the 'collection' child element plus additional unrecognized
      elements, it should generally be treated as a collection.  If the
      element contains no recognized child elements, it should be
      treated as a non-collection resource.  The default value is empty.

   Extensibility:  MAY be extended with any child elements or attributes
      which SHOULD be ignored if not recognized.

   Example: (fictional example to show extensibility)

       <x:resourcetype xmlns:x="DAV:">
           <x:collection/>
           <f:search-results xmlns:f="http://www.example.com/ns"/>
       </x:resourcetype>

14.10.  supportedlock Property

   Name:  supportedlock

   Purpose:  To provide a listing of the lock capabilities supported by
      the resource.

   Protected:  MUST be protected.  Servers determine what lock
      mechanisms are supported, not clients.

   COPY/MOVE behaviour:  This property value is dependent on the kind of
      locks supported at the destination, not on the value of the
      property at the source resource.  Servers attempting to COPY to a
      destination should not attempt to set this property at the
      destination.

   Description:  Returns a listing of the combinations of scope and
      access types which may be specified in a lock request on the
      resource.  Note that the actual contents are themselves controlled
      by access controls so a server is not required to provide
      information the client is not authorized to see.

   Extensibility:  MAY be extended with any child elements or attributes
      which SHOULD be ignored if not recognized.

   <!ELEMENT supportedlock (lockentry)* >



Dusseault                 Expires July 3, 2006                 [Page 98]

Internet-Draft                   WebDAV                    December 2005


14.10.1.  Example - Retrieving the DAV:supportedlock Property

   >>Request

     PROPFIND /container/ HTTP/1.1
     Host: www.example.com
     Content-Length: xxxx
     Content-Type: application/xml; charset="utf-8"

     <?xml version="1.0" encoding="utf-8" ?>
     <D:propfind xmlns:D="DAV:">
       <D:prop><D:supportedlock/></D:prop>
     </D:propfind>

   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: application/xml; charset="utf-8"
     Content-Length: xxxx

     <?xml version="1.0" encoding="utf-8" ?>
     <D:multistatus xmlns:D="DAV:">
       <D:response>
         <D:href>http://www.example.com/container/</D:href>
         <D:propstat>
           <D:prop>
             <D:supportedlock>
               <D:lockentry>
                 <D:lockscope><D:exclusive/></D:lockscope>
                 <D:locktype><D:write/></D:locktype>
               </D:lockentry>
               <D:lockentry>
                 <D:lockscope><D:shared/></D:lockscope>
                 <D:locktype><D:write/></D:locktype>
               </D:lockentry>
             </D:supportedlock>
           </D:prop>
           <D:status>HTTP/1.1 200 OK</D:status>
         </D:propstat>
       </D:response>
     </D:multistatus>










Dusseault                 Expires July 3, 2006                 [Page 99]

Internet-Draft                   WebDAV                    December 2005


15.  Precondition/postcondition XML elements

   As introduced in section Section 8.1.5, extra information on error
   conditions can be included in the body of many status responses.
   This section makes requirements on the use of the error body
   mechanism and introduces a number of precondition and postcondition
   codes.

   A "precondition" of a method describes the state of the server that
   must be true for that method to be performed.  A "postcondition" of a
   method describes the state of the server that must be true after that
   method has been completed.

   Each precondition and postcondition has a unique XML element
   associated with it.  In a 207 Multi-Status response, the XML element
   MUST appear inside a DAV:error element in the appropriate DAV:
   responsedescription element.  In all other error responses, the XML
   element MUST be returned as the child of a top-level DAV:error
   element in the response body, unless otherwise negotiated by the
   request, along with an appropriate response status.  The most common
   response status codes are 403 (Forbidden) if the request should not
   be repeated because it will always fail, and 409 (Conflict) if it is
   expected that the user might be able to resolve the conflict and
   resubmit the request.  The DAV:error element MAY contain child
   elements with specific error information and MAY be extended with
   custom child elements and text (mixed content).

   This mechanism does not take the place of using a correct numeric
   error code as defined here or in HTTP, because the client MUST always
   be able to take a reasonable course of action based only on the
   numeric error.  However, it does remove the need to define new
   numeric error codes.  The machine-readable codes used for this
   purpose are XML elements classified as preconditions and
   postconditions, so naturally any group defining a new error code can
   use their own namespace.  As always, the "DAV:" namespace is reserved
   for use by IETF-chartered WebDAV working groups.

   A server supporting "bis" SHOULD use the XML error whenever a
   precondition or postcondition defined in this document is violated.
   For error conditions not specified in this document, the server MAY
   simply choose an appropriate numeric status and leave the response
   body blank.  However, a server MAY instead use a custom error code
   and other supporting text, because even when clients do not
   automatically recognize error codes they can be quite useful in
   interoperability testing and debugging.






Dusseault                 Expires July 3, 2006                [Page 100]

Internet-Draft                   WebDAV                    December 2005


15.1.  Example - Response with precondition code

   >>Response

      HTTP/1.1 423 Locked
      Content-Type: application/xml; charset="utf-8"
      Content-Length: xxxx

      <?xml version="1.0" encoding="utf-8" ?>
      <D:error xmlns:D="DAV:">
        <D:lock-token-present>
          <D:href>/workspace/webdav/</D:href>
        </D:lock-token-present>
      </D:error>

   In this example, a client unaware of a "Depth: infinity" lock on the
   parent collection "/workspace/webdav/" attempted to modify the
   collection member "/workspace/webdav/proposal.doc".

   Some other useful preconditions and postconditions have been defined
   in other specifications extending WebDAV, such as [RFC3744] (see
   particularly section 7.1.1), [RFC3253], and [RFC3648].

   All these elements are in the "DAV:" namespace.

   Name: no-external-entities

   Use with: 403 Forbidden

   Purpose: (precondition) -- If the server rejects a client request
      because the request body contains an external entity, the server
      SHOULD use this error.

   <!ELEMENT no-external-entities EMPTY >

   Name: lock-token-matches-request-uri

   Use with: 400 Bad Request

   Purpose: (precondition) -- A request may include a Lock-Token header
      to identify a lock for the purposes of an operation such as
      refresh LOCK or UNLOCK.  However, if the Request-URI doe not fall
      within the scope of the lock identified by the token, the server
      SHOULD use this error.  The lock may have a scope that does not
      include the Request-URI, or the lock could have disappeared, or
      the token may be invalid.

   <!ELEMENT lock-token-matches-request-uri EMPTY >



Dusseault                 Expires July 3, 2006                [Page 101]

Internet-Draft                   WebDAV                    December 2005


   Name: preserved-live-properties

   Use with: 409 Conflict

   Purpose: (postcondition) -- The server received an otherwise-valid
      MOVE or COPY request, but cannot maintain the live properties with
      the same behavior at the destination.  It may be that the server
      only supports some live properties in some parts of the
      repository, or simply has an internal error.

   <!ELEMENT preserved-live-properties EMPTY >

   Name: writable-property

   Use with: 403 Forbidden

   Purpose: (precondition) -- The client attempted to set a read-only
      property in a PROPPATCH (such as DAV:getetag).

   <!ELEMENT writable-property EMPTY >

   Name: propfind-finite-depth

   Use with: 403 Forbidden

   Purpose: (precondition) -- This server does not allow infinite-depth
      PROPFIND requests on collections.

   <!ELEMENT propfind-finite-depth EMPTY >

   Name: lock-token-present

   Use with: 4xx responses, e.g. 400 Bad Request or 423 Locked

   Purpose: (precondition) -- The request could not succeed because a
      lock token should have been provided.  This element, if present,
      MUST contain at least one URL of a locked resource that prevented
      the request.  In cases of MOVE, COPY and DELETE where collection
      locks are involved, it can be difficult for the client to find out
      which locked resource made the request fail -- but the server is
      only resonsible for returning one such locked resource.  The
      server MAY return every locked resource that prevented the request
      from succeeding if it knows them all.

   <!ELEMENT lock-token-present (href+) >






Dusseault                 Expires July 3, 2006                [Page 102]

Internet-Draft                   WebDAV                    December 2005


16.  Instructions for Processing XML in DAV

   All DAV compliant resources MUST ignore any unknown XML element and
   all its children encountered while processing a DAV method that uses
   XML as its command language.

   This restriction also applies to the processing, by clients, of DAV
   property values where unknown XML elements SHOULD be ignored unless
   the property's schema declares otherwise.

   This restriction does not apply to setting dead DAV properties on the
   server where the server MUST record unknown XML elements.

   Additionally, this restriction does not apply to the use of XML where
   XML happens to be the content type of the entity body, for example,
   when used as the body of a PUT.

   Since XML can be transported as text/xml or application/xml, a DAV
   server MUST accept DAV method requests with XML parameters
   transported as either text/xml or application/xml, and a DAV client
   MUST accept XML responses using either text/xml or application/xml.

   XML DTD fragments are included for all the XML elements defined in
   this specification.  However, legal XML may not be valid according to
   any DTD due to namespace usage and extension rules, so the DTD is
   only informational.  A recipient of a WebDAV message with an XML body
   MUST NOT validate the XML document according to any hard-coded or
   dynamically-declared DTD.























Dusseault                 Expires July 3, 2006                [Page 103]

Internet-Draft                   WebDAV                    December 2005


17.  DAV Compliance Classes

   A DAV compliant resource can advertise several classes of compliance.
   A client can discover the compliance classes of a resource by
   executing OPTIONS on the resource, and examining the "DAV" header
   which is returned.  Note particularly that resources are spoken of as
   being compliant, rather than servers.  That is because theoretically
   some resources on a server could support different feature sets.
   E.g. a server could have a sub-repository where an advanced feature
   like server was supported, even if that feature was not supported on
   all servers.

   Since this document describes extensions to the HTTP/1.1 protocol,
   minimally all DAV compliant resources, clients, and proxies MUST be
   compliant with [RFC2616].

   A resource that is class 2 compliant must also be class 1 compliant,
   and a resource that is compliant with "bis" must also be class 1
   compliant.

17.1.  Class 1

   A class 1 compliant resource MUST meet all "MUST" requirements in all
   sections of this document.

   Class 1 compliant resources MUST return, at minimum, the value "1" in
   the DAV header on all responses to the OPTIONS method.

17.2.  Class 2

   A class 2 compliant resource MUST meet all class 1 requirements and
   support the LOCK method, the DAV:supportedlock property, the DAV:
   lockdiscovery property, the Time-Out response header and the Lock-
   Token request header.  A class "2" compliant resource SHOULD also
   support the Time-Out request header and the owner XML element.

   Class 2 compliant resources MUST return, at minimum, the values "1"
   and "2" in the DAV header on all responses to the OPTIONS method.

17.3.  Class 'bis'

   A resource can explicitly advertise its support for the revisions to
   RFC2518 made in this document.  Class 1 must be supported as well.
   Class 2 MAY be supported.

   Example:

            DAV: 1, bis



Dusseault                 Expires July 3, 2006                [Page 104]

Internet-Draft                   WebDAV                    December 2005


18.  Internationalization Considerations

   In the realm of internationalization, this specification complies
   with the IETF Character Set Policy [RFC2277].  In this specification,
   human-readable fields can be found either in the value of a property,
   or in an error message returned in a response entity body.  In both
   cases, the human-readable content is encoded using XML, which has
   explicit provisions for character set tagging and encoding, and
   requires that XML processors read XML elements encoded, at minimum,
   using the UTF-8 [RFC3629] and UTF-16 encodings of the ISO 10646
   multilingual plane.  XML examples in this specification demonstrate
   use of the charset parameter of the Content-Type header, as defined
   in [RFC3023], as well as the XML declarations which provide charset
   identification information for MIME and XML processors.

   XML also provides a language tagging capability for specifying the
   language of the contents of a particular XML element.  The "xml:lang"
   attribute appears on an XML element to identify the language of its
   content and attributes.  See [XML] for definitions of values and
   scoping.

   WebDAV applications MUST support the character set tagging, character
   set encoding, and the language tagging functionality of the XML
   specification.  Implementors of WebDAV applications are strongly
   encouraged to read "XML Media Types" [RFC3023] for instruction on
   which MIME media type to use for XML transport, and on use of the
   charset parameter of the Content-Type header.

   Names used within this specification fall into four categories: names
   of protocol elements such as methods and headers, names of XML
   elements, names of properties, and names of conditions.  Naming of
   protocol elements follows the precedent of HTTP, using English names
   encoded in USASCII for methods and headers.  Since these protocol
   elements are not visible to users, and are simply long token
   identifiers, they do not need to support multiple languages.
   Similarly, the names of XML elements used in this specification are
   not visible to the user and hence do not need to support multiple
   languages.

   WebDAV property names are qualified XML names (pairs of XML namespace
   name and local name).  Although some applications (e.g., a generic
   property viewer) will display property names directly to their users,
   it is expected that the typical application will use a fixed set of
   properties, and will provide a mapping from the property name and
   namespace to a human-readable field when displaying the property name
   to a user.  It is only in the case where the set of properties is not
   known ahead of time that an application need display a property name
   to a user.  We recommend that applications provide human-readable



Dusseault                 Expires July 3, 2006                [Page 105]

Internet-Draft                   WebDAV                    December 2005


   property names wherever feasible.

   For error reporting, we follow the convention of HTTP/1.1 status
   codes, including with each status code a short, English description
   of the code (e.g., 423 (Locked)).  While the possibility exists that
   a poorly crafted user agent would display this message to a user,
   internationalized applications will ignore this message, and display
   an appropriate message in the user's language and character set.

   Since interoperation of clients and servers does not require locale
   information, this specification does not specify any mechanism for
   transmission of this information.







































Dusseault                 Expires July 3, 2006                [Page 106]

Internet-Draft                   WebDAV                    December 2005


19.  Security Considerations

   This section is provided to detail issues concerning security
   implications of which WebDAV applications need to be aware.

   All of the security considerations of HTTP/1.1 (discussed in
   [RFC2616]) and XML (discussed in [RFC3023]) also apply to WebDAV.  In
   addition, the security risks inherent in remote authoring require
   stronger authentication technology, introduce several new privacy
   concerns, and may increase the hazards from poor server design.
   These issues are detailed below.

19.1.  Authentication of Clients

   Due to their emphasis on authoring, WebDAV servers need to use
   authentication technology to protect not just access to a network
   resource, but the integrity of the resource as well.  Furthermore,
   the introduction of locking functionality requires support for
   authentication.

   A password sent in the clear over an insecure channel is an
   inadequate means for protecting the accessibility and integrity of a
   resource as the password may be intercepted.  Since Basic
   authentication for HTTP/1.1 performs essentially clear text
   transmission of a password, Basic authentication MUST NOT be used to
   authenticate a WebDAV client to a server unless the connection is
   secure.  Furthermore, a WebDAV server MUST NOT send Basic
   authentication credentials in a WWW-Authenticate header unless the
   connection is secure.  Examples of secure connections include a
   Transport Layer Security (TLS) connection employing a strong cipher
   suite with mutual authentication of client and server, or a
   connection over a network which is physically secure, for example, an
   isolated network in a building with restricted access.

   WebDAV applications MUST support the Digest authentication scheme
   [RFC2617].  Since Digest authentication verifies that both parties to
   a communication know a shared secret, a password, without having to
   send that secret in the clear, Digest authentication avoids the
   security problems inherent in Basic authentication while providing a
   level of authentication which is useful in a wide range of scenarios.

19.2.  Denial of Service

   Denial of service attacks are of special concern to WebDAV servers.
   WebDAV plus HTTP enables denial of service attacks on every part of a
   system's resources.





Dusseault                 Expires July 3, 2006                [Page 107]

Internet-Draft                   WebDAV                    December 2005


   o  The underlying storage can be attacked by PUTting extremely large
      files.

   o  Asking for recursive operations on large collections can attack
      processing time.

   o  Making multiple pipelined requests on multiple connections can
      attack network connections.

   WebDAV servers need to be aware of the possibility of a denial of
   service attack at all levels.  The proper response to such an attack
   MAY be to simply drop the connection, or if the server is able to
   make a response, the server MAY use a 400-level status request such
   as 400 (Bad Request) and indicate why the request was refused (a 500-
   level status response would indicate that the problem is with the
   server, whereas unintentional DOS attacks are something the client is
   capable of remedying).

19.3.  Security through Obscurity

   WebDAV provides, through the PROPFIND method, a mechanism for listing
   the member resources of a collection.  This greatly diminishes the
   effectiveness of security or privacy techniques that rely only on the
   difficulty of discovering the names of network resources.  Users of
   WebDAV servers are encouraged to use access control techniques to
   prevent unwanted access to resources, rather than depending on the
   relative obscurity of their resource names.

19.4.  Privacy Issues Connected to Locks

   When submitting a lock request a user agent may also submit an owner
   XML field giving contact information for the person taking out the
   lock (for those cases where a person, rather than a robot, is taking
   out the lock).  This contact information is stored in a DAV:
   lockdiscovery property on the resource, and can be used by other
   collaborators to begin negotiation over access to the resource.
   However, in many cases this contact information can be very private,
   and should not be widely disseminated.  Servers SHOULD limit read
   access to the DAV:lockdiscovery property as appropriate.
   Furthermore, user agents SHOULD provide control over whether contact
   information is sent at all, and if contact information is sent,
   control over exactly what information is sent.

19.5.  Privacy Issues Connected to Properties

   Since property values are typically used to hold information such as
   the author of a document, there is the possibility that privacy
   concerns could arise stemming from widespread access to a resource's



Dusseault                 Expires July 3, 2006                [Page 108]

Internet-Draft                   WebDAV                    December 2005


   property data.  To reduce the risk of inadvertent release of private
   information via properties, servers are encouraged to develop access
   control mechanisms that separate read access to the resource body and
   read access to the resource's properties.  This allows a user to
   control the dissemination of their property data without overly
   restricting access to the resource's contents.

19.6.  Implications of XML Entities

   XML supports a facility known as "external entities", defined in
   section 4.2.2 of [XML], which instruct an XML processor to retrieve
   and include additional XML.  An external XML entity can be used to
   append or modify the document type declaration (DTD) associated with
   an XML document.  An external XML entity can also be used to include
   XML within the content of an XML document.  For non-validating XML,
   such as the XML used in this specification, including an external XML
   entity is not required by XML.  However, XML does state that an XML
   processor may, at its discretion, include the external XML entity.

   External XML entities have no inherent trustworthiness and are
   subject to all the attacks that are endemic to any HTTP GET request.
   Furthermore, it is possible for an external XML entity to modify the
   DTD, and hence affect the final form of an XML document, in the worst
   case significantly modifying its semantics, or exposing the XML
   processor to the security risks discussed in [RFC3023].  Therefore,
   implementers must be aware that external XML entities should be
   treated as untrustworthy.  If a server implementor chooses not to
   handle external XML entities, it SHOULD respond to requests
   containing external entities with the precondition defined above (no-
   external-entities).

   There is also the scalability risk that would accompany a widely
   deployed application which made use of external XML entities.  In
   this situation, it is possible that there would be significant
   numbers of requests for one external XML entity, potentially
   overloading any server which fields requests for the resource
   containing the external XML entity.

   Furthermore, there's also a risk based on the evaluation of "internal
   entities" as defined in section 4.2.2 of [XML].  A small, carefully
   crafted request using nested internal entities may require enormous
   amounts of memory and/or processing time to process.  Server
   implementors should be aware of this risk and configure their XML
   parsers so that requests like these can be detected and rejected as
   early as possible.






Dusseault                 Expires July 3, 2006                [Page 109]

Internet-Draft                   WebDAV                    December 2005


19.7.  Risks Connected with Lock Tokens

   This specification encourages the use of "A Universally Unique
   Identifier (UUID) URN Namespace" ([RFC4122]) for lock tokens
   Section 6.3, in order to guarantee their uniqueness across space and
   time.  Variant 1 UUIDs (defined in section 4) MAY contain a "node"
   field that "consists of an IEEE 802 MAC address, usually the host
   address.  For systems with multiple IEEE addresses, any available one
   can be used".

   There are several risks associated with exposure of IEEE 802
   addresses.  Using the IEEE 802 address:

   o  It is possible to track the movement of hardware from subnet to
      subnet.

   o  It may be possible to identify the manufacturer of the hardware
      running a WebDAV server.

   o  It may be possible to determine the number of each type of
      computer running WebDAV.

   This risk only applies to host address based UUID versions.  Section
   4 of [RFC4122] describes several other mechanisms for generating
   UUIDs that do involve the host address and therefore do not suffer
   from this risk.

19.8.  Hosting malicious scripts executed on client machines

   HTTP has the ability to host scripts which are executed on client
   machines.  These scripts can be used to read another user's cookies
   and therefore may provide an attacker the ability to use another
   user's session, assume their identity temporarily and gain access to
   their resources.  Other attacks are also possible with client-
   executed scripts.

   WebDAV may worsen this situation only by making it easier for a Web
   server to host content provided by many different authors (making it
   harder to trust the content providers) and to host content with
   restricted access alongside public pages (see particularly RFC3744).

   HTTP servers may mitigate some of these threats by filtering content
   in areas where many authors contribute pages -- the server could, for
   example, remove script from HTML pages.

   This vulnerability should provide yet another reason for server
   implementors and administrators not to replace authentication
   mechanisms with cookie-based session tokens if there's any sensitive



Dusseault                 Expires July 3, 2006                [Page 110]

Internet-Draft                   WebDAV                    December 2005


   information relying on the authenticated identity.

   HTTP and WebDAV client implementors might consider locking down the
   use of scripts and cookies based on these considerations.















































Dusseault                 Expires July 3, 2006                [Page 111]

Internet-Draft                   WebDAV                    December 2005


20.  IANA Considerations

   This specification defines two URI schemes:

   1.  the "opaquelocktoken" scheme defined in Appendix C, and

   2.  the "DAV" URI scheme, which historically was used in RFC2518 to
       disambiguate WebDAV property and XML element names and which
       continues to be used for that purpose in this specification and
       others extending WebDAV.  Creation of identifiers in the "DAV:"
       namespace is controlled by the IETF.

   XML namespaces disambiguate WebDAV property names and XML elements.
   Any WebDAV user or application can define a new namespace in order to
   create custom properties or extend WebDAV XML syntax.  IANA does not
   need to manage such namespaces, property names or element names.



































Dusseault                 Expires July 3, 2006                [Page 112]

Internet-Draft                   WebDAV                    December 2005


21.  Acknowledgements

   A specification such as this thrives on piercing critical review and
   withers from apathetic neglect.  The authors gratefully acknowledge
   the contributions of the following people, whose insights were so
   valuable at every stage of our work.

   Contributors to RFC2518

   Terry Allen, Harald Alvestrand, Jim Amsden, Becky Anderson, Alan
   Babich, Sanford Barr, Dylan Barrell, Bernard Chester, Tim Berners-
   Lee, Dan Connolly, Jim Cunningham, Ron Daniel, Jr., Jim Davis, Keith
   Dawson, Mark Day, Brian Deen, Martin Duerst, David Durand, Lee
   Farrell, Chuck Fay, Wesley Felter, Roy Fielding, Mark Fisher, Alan
   Freier, George Florentine, Jim Gettys, Phill Hallam-Baker, Dennis
   Hamilton, Steve Henning, Mead Himelstein, Alex Hopmann, Andre van der
   Hoek, Ben Laurie, Paul Leach, Ora Lassila, Karen MacArthur, Steven
   Martin, Larry Masinter, Michael Mealling, Keith Moore, Thomas Narten,
   Henrik Nielsen, Kenji Ota, Bob Parker, Glenn Peterson, Jon Radoff,
   Saveen Reddy, Henry Sanders, Christopher Seiwald, Judith Slein, Mike
   Spreitzer, Einar Stefferud, Greg Stein, Ralph Swick, Kenji Takahashi,
   Richard N. Taylor, Robert Thau, John Turner, Sankar Virdhagriswaran,
   Fabio Vitali, Gregory Woodhouse, and Lauren Wood.

   Two from this list deserve special mention.  The contributions by
   Larry Masinter have been invaluable, both in helping the formation of
   the working group and in patiently coaching the authors along the
   way.  In so many ways he has set high standards we have toiled to
   meet.  The contributions of Judith Slein in clarifying the
   requirements, and in patiently reviewing draft after draft, both
   improved this specification and expanded our minds on document
   management.

   We would also like to thank John Turner for developing the XML DTD.

   The authors of RFC2518 were Yaron Goland, Jim Whitehead, A. Faizi,
   Steve Carter and D. Jensen.  Although their names had to be removed
   due to IETF author count restrictions they can take credit for the
   majority of the design of WebDAV.

   Additional Contributors to This Specification

   Valuable contributions to this specification came from some already
   named.  New and significant contributors to this specification must
   also be gratefully acknowledged.  Julian Reschke, Geoff Clemm, Joel
   Soderberg, and Dan Brotsky hashed out specific text on the list or in
   meetings.  Joe Hildebrand and Cullen Jennings helped close many
   issues.  Barry Lind described an additional security consideration.



Dusseault                 Expires July 3, 2006                [Page 113]

Internet-Draft                   WebDAV                    December 2005


   Jason Crawford tracked issue status for this document for a period of
   years, followed by Elias Sinderson.  Elias and Jim Whitehead
   collaborated on specific document text.

21.1.  Previous Authors' Addresses

   Y. Y. Goland, Microsoft Corporation, One Microsoft Way, Redmond, WA
   98052-6399.  Email: yarong@microsoft.com.

   E. J. Whitehead, Jr., Dept.  Of Information and Computer Science,
   University of California, Irvine, Irvine, CA 92697-3425.  Email:
   ejw@ics.uci.edu.

   A. Faizi, Netscape, 685 East Middlefield Road, Mountain View, CA
   94043.  Email: asad@netscape.com.

   S. R. Carter, Novell, 1555 N. Technology Way, M/S ORM F111, Orem, UT
   84097-2399.  Email: srcarter@novell.com.

   D. Jensen, Novell, 1555 N. Technology Way, M/S ORM F111, Orem, UT
   84097-2399.  Email: dcjensen@novell.com.






























Dusseault                 Expires July 3, 2006                [Page 114]

Internet-Draft                   WebDAV                    December 2005


22.  References

22.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2277]  Alvestrand, H., "IETF Policy on Character Sets and
              Languages", BCP 18, RFC 2277, January 1998.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC2617]  Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
              Leach, P., Luotonen, A., and L. Stewart, "HTTP
              Authentication: Basic and Digest Access Authentication",
              RFC 2617, June 1999.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, July 2002.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              July 2005.

   [W3C.REC-xml-names-19990114]
              Hollander, D., Bray, T., and A. Layman, "Namespaces in
              XML", W3C REC REC-xml-names-19990114, January 1999.

   [XML]      Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and
              F. Yergeau, "Extensible Markup Language (XML) 1.0 (Third
              Edition)", W3C REC-xml-20040204, February 2004,
              <http://www.w3.org/TR/2004/REC-xml-20040204>.

22.2.  Informational References

   [RFC2291]  Slein, J., Vitali, F., Whitehead, E., and D. Durand,
              "Requirements for a Distributed Authoring and Versioning
              Protocol for the World Wide Web", RFC 2291, February 1998.




Dusseault                 Expires July 3, 2006                [Page 115]

Internet-Draft                   WebDAV                    December 2005


   [RFC2518]  Goland, Y., Whitehead, E., Faizi, A., Carter, S., and D.
              Jensen, "HTTP Extensions for Distributed Authoring --
              WEBDAV", RFC 2518, February 1999.

   [RFC3023]  Murata, M., St. Laurent, S., and D. Kohn, "XML Media
              Types", RFC 3023, January 2001.

   [RFC3253]  Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J.
              Whitehead, "Versioning Extensions to WebDAV (Web
              Distributed Authoring and Versioning)", RFC 3253,
              March 2002.

   [RFC3648]  Whitehead, J. and J. Reschke, Ed., "Web Distributed
              Authoring and Versioning (WebDAV) Ordered Collections
              Protocol", RFC 3648, December 2003.

   [RFC3744]  Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, "Web
              Distributed Authoring and Versioning (WebDAV) Access
              Control Protocol", RFC 3744, May 2004.

   [W3C.REC-xml-infoset-20040204]
              Tobin, R. and J. Cowan, "XML Information Set (Second
              Edition)", W3C REC REC-xml-infoset-20040204,
              February 2004.



























Dusseault                 Expires July 3, 2006                [Page 116]

Internet-Draft                   WebDAV                    December 2005


Appendix A.  Notes on Processing XML Elements

A.1.  Notes on Empty XML Elements

   XML supports two mechanisms for indicating that an XML element does
   not have any content.  The first is to declare an XML element of the
   form <A></A>.  The second is to declare an XML element of the form
   <A/>.  The two XML elements are semantically identical.

A.2.  Notes on Illegal XML Processing

   XML is a flexible data format that makes it easy to submit data that
   appears legal but in fact is not.  The philosophy of "Be flexible in
   what you accept and strict in what you send" still applies, but it
   must not be applied inappropriately.  XML is extremely flexible in
   dealing with issues of white space, element ordering, inserting new
   elements, etc.  This flexibility does not require extension,
   especially not in the area of the meaning of elements.

   There is no kindness in accepting illegal combinations of XML
   elements.  At best it will cause an unwanted result and at worst it
   can cause real damage.

A.3.  Example - XML Syntax Error

   The following request body for a PROPFIND method is illegal.

      <?xml version="1.0" encoding="utf-8" ?>
      <D:propfind xmlns:D="DAV:">
       <D:allprop/>
       <D:propname/>
      </D:propfind>

   The definition of the propfind element only allows for the allprop or
   the propname element, not both.  Thus the above is an error and must
   be responded to with a 400 (Bad Request).

   Imagine, however, that a server wanted to be "kind" and decided to
   pick the allprop element as the true element and respond to it.  A
   client running over a bandwidth limited line who intended to execute
   a propname would be in for a big surprise if the server treated the
   command as an allprop.

   Additionally, if a server were lenient and decided to reply to this
   request, the results would vary randomly from server to server, with
   some servers executing the allprop directive, and others executing
   the propname directive.  This reduces interoperability rather than
   increasing it.



Dusseault                 Expires July 3, 2006                [Page 117]

Internet-Draft                   WebDAV                    December 2005


A.4.  Example - Unknown XML Element

   The previous example was illegal because it contained two elements
   that were explicitly banned from appearing together in the propfind
   element.  However, XML is an extensible language, so one can imagine
   new elements being defined for use with propfind.  Below is the
   request body of a PROPFIND and, like the previous example, must be
   rejected with a 400 (Bad Request) by a server that does not
   understand the expired-props element.

      <?xml version="1.0" encoding="utf-8" ?>
      <D:propfind xmlns:D="DAV:"
      xmlns:E="http://www.example.com/standards/props/">
       <E:expired-props/>
      </D:propfind>

   To understand why a 400 (Bad Request) is returned let us look at the
   request body as the server unfamiliar with expired-props sees it.

      <?xml version="1.0" encoding="utf-8" ?>
      <D:propfind xmlns:D="DAV:"
                  xmlns:E="http://www.example.com/standards/props/">
      </D:propfind>

   As the server does not understand the 'expired-props' element,
   according to the WebDAV-specific XML processing rules specified in
   Section 16, it must ignore it.  Thus the server sees an empty
   propfind, which by the definition of the propfind element is illegal.

   Please note that had the extension been additive it would not
   necessarily have resulted in a 400 (Bad Request).  For example,
   imagine the following request body for a PROPFIND:


      <?xml version="1.0" encoding="utf-8" ?>
      <D:propfind xmlns:D="DAV:"
                  xmlns:E="http://www.example.com/standards/props/">
       <D:propname/>
       <E:leave-out>*boss*</E:leave-out>
      </D:propfind>

   The previous example contains the fictitious element leave-out.  Its
   purpose is to prevent the return of any property whose name matches
   the submitted pattern.  If the previous example were submitted to a
   server unfamiliar with 'leave-out', the only result would be that the
   'leave-out' element would be ignored and a propname would be
   executed.




Dusseault                 Expires July 3, 2006                [Page 118]

Internet-Draft                   WebDAV                    December 2005


Appendix B.  Notes on HTTP Client Compatibility

   The PUT and DELETE methods are defined in HTTP and thus may be used
   by HTTP clients, but the responses to PUT and DELETE have been
   extended in this specification, so some special consideration on
   backward compatibility is worthwhile.

   First, if a PUT or DELETE request includes a header defined in this
   specification (Depth or If), the server can assume the request comes
   from a WebDAV-compatible client.  The server may even be able to
   track a number of requests across a session and know that a client is
   a WebDAV client.  However, this kind of detection may not be
   necessary.

   Since any HTTP client ought to handle unrecognized 400-level and 500-
   level status codes as errors, the following new status codes should
   not present any issues: 422, 423 and 507. 424 is also a new status
   code but it appears only in the body of a Multistatus response.  So,
   for example, if a HTTP client attempted to PUT or DELETE a locked
   resource, the 423 Locked response ought to result in a generic error
   presented to the user.

   The 207 Multistatus response is interesting because a HTTP client
   issuing a DELETE request to a collection might interpret a 207
   response as a success, even though it does not realize the resource
   is a collection and cannot understand that the DELETE operation might
   have been a complete or partial failure.  Thus, a server MAY choose
   to treat a DELETE of a collection as an atomic operation, and use
   either 204 No Content in case of success, or some appropriate error
   response (400 or 500 level) depending on what the error was.  This
   approach would maximize backward compatibility.  However, since
   interoperability tests and working group discussions have not turned
   up any instances of HTTP clients issuing a DELETE request against a
   WebDAV collection, this concern may be more theoretical than
   practical.  Thus, servers MAY instead choose to treat any such DELETE
   request as a WebDAV request, and send a 207 Multistatus containing
   more detail about what resources could not be deleted.














Dusseault                 Expires July 3, 2006                [Page 119]

Internet-Draft                   WebDAV                    December 2005


Appendix C.  The opaquelocktoken scheme and URIs

   The 'opaquelocktoken' URI scheme was defined in RFC2518 (and
   registered by IANA) in order to create syntactically correct and
   easy-to-generate URIs out of UUIDs, intended to be used as lock
   tokens and to be unique across all resources for all time.

   An opaquelocktoken URI is constructed by concatenating the
   'opaquelocktoken' scheme with a UUID, along with an optional
   extension.  Servers can create new UUIDs for each new lock token.  If
   a server wishes to reuse UUIDs the server MUST add an extension and
   the algorithm generating the extension MUST guarantee that the same
   extension will never be used twice with the associated UUID.

     OpaqueLockToken-URI = "opaquelocktoken:" UUID [Extension]
       ; UUID is defined in section 3 of RFC4122. Note that linear white
       ; space (LWS) is not allowed between elements of this production.

     Extension = path
        ; path is defined in section 3.3 of RFC3986































Dusseault                 Expires July 3, 2006                [Page 120]

Internet-Draft                   WebDAV                    December 2005


Appendix D.  Guidance for Clients Desiring to Authenticate

   Many WebDAV clients already implemented have account settings
   (similar to the way email clients store IMAP account settings).
   Thus, the WebDAV client would be able to authenticate with its first
   couple requests to the server, provided it had a way to get the
   authentication challenge from the server with realm name, nonce and
   other challenge information.  Note that the results of some requests
   might vary according to whether the client is authenticated or not --
   a PROPFIND might return more visible resources if the client is
   authenticated, yet not fail if the client is anonymous.

   There are a number of ways the client might be able to trigger the
   server do provide an authentication challenge.  This appendix
   describes a couple approaches that seem particularly likely to work.

   The first approach is to perform a request that ought to require
   authentication.  However, it's possible that a server might handle
   any request even without authentication, so to be entirely safe the
   client could add a conditional header to ensure that even if the
   request passes permissions checks it's not actually handled by the
   server.  An example of following this approach would be to use a PUT
   request with an "If-Match" header with a made-up ETag value.  This
   approach might fail to result in an authentication challenge if the
   server does not test authorization before testing conditionals as is
   required (see Section 8.1.3), or if the server does not need to test
   authorization.

   Example - forcing auth challenge with write request

   >>Request

     PUT /forceauth.txt HTTP/1.1
     Host: www.example.com
     If-Match: "xxx"
     Content-Type: text/plain
     Content-Length: 0


   The second approach is to use an Authorization header (defined in
   [RFC2617]) which is likely to be rejected by the server but which
   will then prompt a proper authentication challenge.  For example, the
   client could start with a PROPFIND request containing an
   Authorization header containing a made-up Basic userid:password
   string or with actual plausible credentials.  This approach relies on
   the server responding with a "401 Unauthorized" along with a
   challenge if it receives an Authorization header with an unrecognized
   username, invalid password, or if it doesn't even handle Basic



Dusseault                 Expires July 3, 2006                [Page 121]

Internet-Draft                   WebDAV                    December 2005


   authentication.  This seems likely to work because of the
   requirements of RFC2617:

   "If the origin server does not wish to accept the credentials sent
   with a request, it SHOULD return a 401 (Unauthorized) response.  The
   response MUST include a WWW-Authenticate header field containing at
   least one (possibly new) challenge applicable to the requested
   resource."

   Example - forcing auth challenge with Authorization header

   >>Request

     PROPFIND /docs/ HTTP/1.1
     Host: www.example.com
     Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
     Content-type: application/xml; charset="utf-8"
     Content-Length: xxxx

     [body omitted]































Dusseault                 Expires July 3, 2006                [Page 122]

Internet-Draft                   WebDAV                    December 2005


Appendix E.  Summary of changes from RFC2518

   This section describes changes that are likely to result in
   implementation changes due to tightened requirements or changed
   behavior.

E.1.  Changes Notable to Server Implementors

   Tightened requirements for storing property values (Section 4.4) when
   "xml:lang" appears and also when values are XML fragments
   (specifically on preserving prefixes, namespaces and whitespace.)

   Tightened requirements on which properties are protected and computed
   (Section 14).

   Several tightened requirements for general response  handling
   (Section 8.1), including response bodies for use with errors, ETag
   and Location header, and reminder to use Date header.

   Tightened requirements for URL construction in PROPFIND (Section 8.2)
   responses.

   Tightened requirements for checking identity of lock  owners
   (Section 7.1) during operations affected by locks.

   Tightened requirements for copying properties (Section 8.9.2) and
   moving properties (Section 8.10.1).

   Tightened requirements on preserving owner field in locks
   (Section 8.11).  Added "lockroot" element to lockdiscovery
   information.

   New value for "DAV:" header (Section 9.1) to advertise support for
   this specification.

   Tightened requirement for "Destination:" header (Section 9.3) to work
   with path values

   Some changes for "If:" header (Section 9.4), including "DAV:no-lock"
   state token and requirement to evaluate entire header.

   Support for UTF-16 now required (ref (Section 18)).

   Removed definition of "source" property and special handling for
   dynamic resources

   Replaced lock-null resources with simpler locked empty resources
   (Section 7.6).  Lock-null resources are now not compliant with the



Dusseault                 Expires July 3, 2006                [Page 123]

Internet-Draft                   WebDAV                    December 2005


   requirements in this specification.

   Encouraged servers to change ETags (Section 8.1.4) only when body of
   resource changes.

   The definition of the 102 Processing response was removed and servers
   ought to stop sending that response when they implement this
   specification.

   Previously, servers were encouraged to return 409 status code in
   response to a collection LOCK request if some resource could not be
   locked.  Now servers should use 207 Multi-Status instead.

   Only 'rfc1123-date' productions are legal as values for DAV:
   getlastmodified.

   New explicit requirement to do authorization checks before
   conditional checks (Section 8.1.3).

E.2.  Changes Notable to Client Implementors

   Tightened requirements for supporting WebDAV collections
   (Section 5.2) within resources that do not support WebDAV (e.g.
   servlet containers).

   Redefined 'allprop' PROPFIND requests so that the server does not
   have to return all properties.

   Required to handle empty multistatus responses in PROPFIND  responses
   (Section 8.2)

   No more "propertybehavior" specification allowed in MOVE and COPY
   requests

   The change in behavior of LOCK with an unmapped URL might affect
   client implementations that counted on lock-null resources
   disappearing when the lock expired.  Clients can no longer rely on
   that cleanup happening.

   Support for UTF-16 now required (ref (Section 18)).

   Removed definition of "source" property and special handling for
   dynamic resources.

   The definition of the 102 Processing response was removed and clients
   can safely remove code (if any) that deals with this.

   Servers may now reject PROPFIND depth "infinity" requests.



Dusseault                 Expires July 3, 2006                [Page 124]

Internet-Draft                   WebDAV                    December 2005


   Clients use Lock-Token header, not the If header, to provide lock
   token when renewing lock.  Section 8.11.1

















































Dusseault                 Expires July 3, 2006                [Page 125]

Internet-Draft                   WebDAV                    December 2005


Appendix F.  Change Log (to be removed by RFC Editor before publication)

F.1.  Changes from -05 to -06

   Specified that a successful LOCK request to an unmapped URL creates a
   new, empty locked resource.

   Resolved UNLOCK_NEEDS_IF_HEADER by clarifying that only Lock-Token
   header is needed on UNLOCK.

   Added Section 15 on preconditions and postconditions and defined a
   number of preconditions and postconditions.  The 'lock-token-present'
   precondition resolves the REPORT_OTHER_RESOURCE_LOCKED issue.

   Added example of matching lock token to URI in the case of a
   collection lock in the If header section.

   Removed ability for Destination header to take "abs_path" in order to
   keep consistent with other places where client provides URLs (If
   header, href element in request body)

   Clarified the href element - that it generally contains HTTP URIs but
   not always.

   Attempted to fix the BNF describing the If header to allow commas

   Clarified presence of Depth header on LOCK refresh requests.

F.2.  Changes in -07

   Added text to "COPY and the Overwrite Header" section to resolve
   issue OVERWRITE_DELETE_ALL_TOO_STRONG.

   Added text to "HTTP URL Namespace Model" section to provide more
   clarification and examples on what consistency means and what is not
   required, to resolve issue CONSISTENCY.

   Resolve DEFINE_PRINCIPAL by importing definition of principal from
   RFC3744.

   Resolve INTEROP_DELETE_AND_MULTISTATUS by adding appendix 3
   discussing backward-compatibility concerns.

   Resolve DATE_FORMAT_GETLASTMODIFIED by allowing only rfc1123-date,
   not HTTP-date for getlastmodified.

   Resolve COPY_INTO_YOURSELF_CLARIFY by adding sentence to first para.
   of COPY section.



Dusseault                 Expires July 3, 2006                [Page 126]

Internet-Draft                   WebDAV                    December 2005


   Confirm that WHEN_TO_MULTISTATUS_FOR_DELETE_1 and
   WHEN_TO_MULTISTATUS_FOR_DELETE_2 are resolved and tweak language in
   DELETE section slightly to be clearly consistent.

   More text clarifications to deal with several of the issues in
   LOCK_ISSUES.  This may not completely resolve that set but we need
   feedback from the originator of the issues at this point.

   Resolved COPY_INTO_YOURSELF_CLARIFY with new sentence in Copy For
   Collections section.

   Double checked that LEVEL_OR_CLASS is resolved by using class, not
   level.

   Further work to resolve IF_AND_AUTH and LOCK_SEMANTICS, clarifying
   text on using locks and being authenticated.

   Added notes on use of 503 status response to resolve issue
   PROPFIND_INFINITY

   Removed section on other uses of Metadata (and associated references)

   Added reference to RFC4122 for lock tokens and removed section on
   generating UUIDs

   Explained that even with language variation, a property has only one
   value (section 4.5).

   Added section on lock owner (7.1) and what to do if lock requested by
   unauthenticated user

   Removed section 4.2 -- justification on why to have metadata, not
   needed now

   Removed paragraph in section 5.2 about collections with resource type
   "DAV:collection" but which are non-WebDAV compliant -- not
   implemented.

F.3.  Changes in -08

   Added security considerations section on scripts and cookie sessions,
   suggested by Barry Lind

   Clarified which error codes are defined and undefined in MultiStatus

   Moved opaquelocktoken definition to an appendix and refer to RFC4122
   for use of 'urn:uuid:' URI scheme; fix all lock token examples to use
   this.



Dusseault                 Expires July 3, 2006                [Page 127]

Internet-Draft                   WebDAV                    December 2005


   Multi-status responses contain URLs which MUST either be absolute
   (and begin with the Request-URI or MUST be relative with new
   limitations. (bug 12)

   Moved status code sections before example sections within PROPFIND
   section for section ordering consistency.

   Clarified use of Location header with Multi-Status

   Bugzilla issue resolutions: bugs 9, 12, 14, 19, 20, 29, 30, 34, 36,
   102 and 172.

F.4.  Changes in -09

   Bugzilla editorial issues: bugs 30, 57, 63, 68, 88, 89, 168, 180,
   182, 185, 187.

   More clarity between URL namespaces and XML namespaces, particularly
   at the beginning of paragraphs using the word namespace

   More consistency in referring to properties with the namespace, as in
   "DAV:lockdiscovery", and referring to XML element names in single
   quotes, e.g. 'allprop' element.

   Figure (example) formatting fixes

   Bugzilla issues: bugs 24, 37, 39, 43, 45, 27, 25

   Replaced references to "non-null state" of resources with more clear
   language about URLs that are mapped to resources, bug 25.  Also added
   definition of URL/URI mapping.  Bug 40.

   Bugzilla issues: bug 7, 8, 9, 41, 47, 51, 62, 93, 171, 172.  Bugs 28
   and 94 were iterated on.

   Bugzilla issues: 56, 59, 79, 99, 103, 175, 178.  Part of bug 23.
   Iteration on bug 10.

   Iteration on bugs 10, 46 and 47.  Bug 11.

   Remove "102 Processing" response

   Fix bug 46, 105, 107, 120, 140 and 201.

   Another stab at bug 12 - relative v. absolute URLs in Multi-Status
   response hrefs

   Fix bug 6, 11, 15, 16, 28, 32, 42, 51, 52, 53, 58, 60, 62, 186, 189,



Dusseault                 Expires July 3, 2006                [Page 128]

Internet-Draft                   WebDAV                    December 2005


   191, 199, 200

   Fix bug 96

F.5.  Chandles in -10

   Clarify lock intro text on when a client might use another client's
   lock token - suggestion by Geoff, Nov 15

   Removed Force-Authenticate header and instead added an appendix
   explaining how existing mechanisms might resolve the need of clients
   to get an authentication challenge (bug 18).

   Bug 62, 113, 125, 131, 143, 144, 171, 193

   Bug 176, 177, 179, 181, 184, 206, 207, 208



































Dusseault                 Expires July 3, 2006                [Page 129]

Internet-Draft                   WebDAV                    December 2005


Author's Address

   Lisa Dusseault
   Open Source Application Foundation
   2064 Edgewood Dr.
   Palo Alto, CA  94303
   US

   Email: lisa@osafoundation.org










































Dusseault                 Expires July 3, 2006                [Page 130]

Internet-Draft                   WebDAV                    December 2005


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Disclaimer of Validity

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
   ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
   INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
   INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Copyright Statement

   Copyright (C) The Internet Society (2005).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.


Acknowledgment

   Funding for the RFC Editor function is currently provided by the
   Internet Society.




Dusseault                 Expires July 3, 2006                [Page 131]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/