Internet Draft©Ą

WebDAV                                                      L. Dusseault, Xythos
Document: draft-ietf-webdav-rfc2518bis-05.txt Dusseault
Internet-Draft                                                      OSAF
Expires: January 15, 2005                                    J. Crawford, Crawford
                                                                     IBM
Expires: Apr
                                                           July 17, 2004

     HTTP Extensions for Distributed Authoring - WebDAV RFC2518 bis
                    draft-ietf-webdav-rfc2518bis-06

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

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   This Internet-Draft will expire on January 15, 2005.

Copyright Notice

   Copyright (C) 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 RFC 2119 [RFC2119]. Internet Society (2004).  All Rights Reserved.

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, namespace
   manipulation, and resource locking (collision avoidance).

   RFC2518 was published in February 1998, and this draft makes minor
   revisions mostly due to interoperability experience.

Table

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 Contents

   1  Introduction...................................................6
   2  Notational Conventions.........................................7
   3  Terminology....................................................7
   4  Data Model for Resource Properties.............................8

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   4.1 methods, headers, request
   entity body formats, and response entity body formats that provide
   operations for:

   Properties: The Resource Property Model..................................8
   4.2  Existing Metadata Proposals..................................8
   4.3  Properties ability to create, remove, and HTTP Headers..................................9
   4.4  XML Usage....................................................9
   4.5  Property Values.............................................10
   4.6  Property Names..............................................11
   5  Collections of query information
   about Web Resources..................................11
   5.1  HTTP URL Namespace Model....................................11
   5.2  Collection Resources........................................12
   5.3  Source Resources and Output Resources.......................13
   6  Locking.......................................................14
   6.1  Exclusive Vs. Shared Locks..................................14
   6.2  Required Support............................................15
   6.3  Lock Tokens.................................................16
   6.4  opaquelocktoken Lock Token URI Scheme.......................16
   6.5  Lock Capability Discovery...................................17
   6.6  Active Lock Discovery.......................................17
   6.7  Usage Considerations........................................17
   7  Write Lock....................................................18
   7.1  Methods Restricted by Write Locks...........................18
   7.2  Write Locks and Lock Tokens.................................18
   7.3  Write Locks and Properties..................................19
   7.4  Write Locks and Unmapped URLs...............................19
   7.5  Write Locks and Collections.................................20
   7.6  Write Locks and pages, such as their authors, creation dates, etc.  Also,
   the If Request Header.......................21
   7.7  Write Locks and COPY/MOVE...................................22
   7.8  Refreshing Write Locks......................................23
   8  HTTP Methods for Distributed Authoring........................23
   8.1  General request and response handling.......................23
   8.1.1 Use ability to link pages of XML.................................................23
   8.1.2 Required Bodies in Requests................................23
   8.1.3 Use of Location header in responses........................24
   8.1.4 Required Response Headers: Date............................24
   8.1.5 ETag.......................................................24
   8.1.6 Including error response bodies............................24
   8.2  PROPFIND....................................................25
   8.2.1 Example - Retrieving Named Properties......................28
   8.2.2 Example - Retrieving Named and Dead Properties.............29
   8.2.3 Example - Using propname to Retrieve all Property Names....29
   8.2.4 PROPFIND Request Errors....................................31
   8.3  PROPPATCH...................................................31
   8.3.1 Status Codes for use with 207 (Multi-Status)...............32
   8.3.2 Example - PROPPATCH........................................32
   8.4  MKCOL Method................................................34
   8.4.1 Example - MKCOL............................................35

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   8.5  GET, HEAD for Collections...................................35
   8.6  POST for Collections........................................35
   8.7  DELETE......................................................36
   8.7.1 Example - DELETE...........................................37
   8.8  PUT.........................................................37
   8.9  COPY Method.................................................38
   8.9.1 COPY for Collections.......................................39
   8.9.2 COPY and the Overwrite Header..............................40
   8.9.3 Status Codes...............................................40
   8.9.4 Example - COPY with Overwrite..............................41
   8.10  MOVE Method................................................42
   8.10.1  MOVE for Properties......................................43
   8.10.2  MOVE for Collections.....................................43
   8.10.3  MOVE and the Overwrite Header............................44
   8.10.4  Status Codes.............................................44
   8.10.5  Example - MOVE of a Non-Collection.......................45
   8.11  LOCK Method................................................46
   8.11.1  Example - Simple Lock Request............................50
   8.11.2  Example - Refreshing a Write Lock........................51
   8.11.3  Example - Multi-Resource Lock Request....................52
   8.12  UNLOCK Method..............................................54
   8.12.1  Example - UNLOCK.........................................54
   9  HTTP Headers for Distributed Authoring........................55
   9.1  DAV Header..................................................55
   9.2  Depth Header................................................56
   9.3  Destination Header..........................................57
   9.4  Force-Authentication Header.................................57
   9.5  If Header...................................................58
   9.5.1 No-tag-list Production.....................................58
   9.5.2 Example - No-tag-list If Header............................59
   9.5.3 Tagged-list Production.....................................59
   9.5.4 Example - Tagged List If header............................59
   9.5.5 Not Production.............................................60
   9.5.6 Matching Function..........................................60
   9.5.7 If Header and Non-DAV Aware Proxies........................60
   9.6  Lock-Token Header...........................................61
   9.7  Overwrite Header............................................61
   9.8  Timeout Request Header......................................61
   10 Status Code Extensions to HTTP/1.1............................62
   10.1  102 Processing.............................................62
   10.2  207 Multi-Status...........................................63
   10.3  422 Unprocessable Entity...................................63
   10.4  423 Locked.................................................63
   10.5  424 Failed Dependency......................................63
   10.6  507 Insufficient Storage...................................63

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   11 Use of HTTP Status Codes......................................63
   11.1  301 Moved Permanently......................................63
   11.2  302 Found..................................................64
   11.3  400 Bad Request............................................64
   11.4  403 Forbidden..............................................64
   11.5  409 Conflict...............................................64
   11.6  414 Request-URI Too Long...................................64
   12 Multi-Status Response.........................................64
   12.1  Responses requiring Location in Multi-Status...............65
   13 XML Element Definitions.......................................65
   13.1  activelock XML Element.....................................66
   13.2  depth XML Element..........................................66
   13.3  locktoken XML Element......................................66
   13.4  lockroot XML Element.......................................66
   13.5  timeout XML Element........................................67
   13.6  collection XML Element.....................................67
   13.7  href XML Element...........................................67
   13.8  lockentry XML Element......................................68
   13.9  lockinfo XML Element.......................................68
   13.10 lockscope XML Element......................................68
   13.11 exclusive XML Element......................................68
   13.12 shared XML Element.........................................68
   13.13 locktype XML Element.......................................69
   13.14 write XML Element..........................................69
   13.15 multistatus XML Element....................................69
   13.16 response XML Element.......................................70
   13.17 propstat XML Element.......................................70
   13.18 status XML Element.........................................70
   13.19 responsedescription XML Element............................71
   13.20 owner XML Element..........................................71
   13.21 prop XML element...........................................71
   13.22 propertyupdate XML element.................................72
   13.23 remove XML element.........................................72
   13.24 set XML element............................................72
   13.25 propfind XML Element.......................................73
   13.26 allprop XML Element........................................73
   13.27 propname XML Element.......................................73
   13.28 dead-props XML Element.....................................73
   13.29 location XML Element.......................................74
   14 DAV Properties................................................74
   14.1  creationdate Property......................................74
   14.2  displayname Property.......................................75
   14.3  getcontentlanguage Property................................75
   14.4  getcontentlength Property..................................76
   14.5  getcontenttype Property....................................76

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   14.6  getetag Property...........................................77
   14.7  getlastmodified Property...................................77
   14.8  lockdiscovery Property.....................................78
   14.8.1  Example - Retrieving the lockdiscovery Property..........79
   14.9  resourcetype Property......................................80
   14.10 supportedlock Property.....................................80
   14.10.1 Example - Retrieving the supportedlock Property..........81
   15 Instructions for Processing XML in DAV........................82
   16 DAV Compliance Classes........................................82
   16.1  Class 1....................................................83
   16.2  Class 2....................................................83
   16.3  Class "bis"................................................83
   17 Internationalization Considerations...........................84
   18 Security Considerations.......................................85
   18.1  Authentication of Clients..................................85
   18.2  Denial of Service..........................................86
   18.3  Security through Obscurity.................................86
   18.4  Privacy Issues Connected to Locks..........................86
   18.5  Privacy Issues Connected to Properties.....................87
   18.6  Implications of XML External Entities......................87
   18.7  Risks Connected with Lock Tokens...........................88
   19 IANA Considerations...........................................88
   20 Intellectual Property.........................................89
   21 Acknowledgements..............................................89
   22 References....................................................91
   22.1  Normative References.......................................91
   22.2  Informational References...................................92
   23 Authors' Addresses............................................93
   24 Appendices....................................................94
   24.1  Appendix 1 - Notes on Processing XML Elements..............94
   24.1.1  Notes on Empty XML Elements..............................94
   24.1.2  Notes on Illegal XML Processing..........................94
   24.1.3  Example - XML Syntax Error...............................94
   24.1.4  Example - Unknown XML Element............................95
   24.2  Appendix 2: UUID Node Generation...........................96
   25 Full Copyright Statement......................................97

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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 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.

   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]. (RFC2291) [15].

   This standard does not specify the versioning operations suggested by [RFC2291].
   RFC2291 [15].  That work was done in a separate document, "Versioning
   Extensions to WebDAV" [RFC3253]. (RFC3253) [18].

   The sections below provide a detailed introduction to resource
   properties (section (Section 4), collections of resources (section (Section 5), and
   locking operations (section (Section 6).  These sections introduce the
   abstractions manipulated by the WebDAV-specific HTTP methods
   described in section 8. Section 9 describes (Section
   8) and the new HTTP headers used with WebDAV methods. methods (Section 9).

   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.  New
   This specification defines new status  codes developed for the WebDAV
   methods are
   defined in section 10, (Section 10) and describes existing HTTP status codes
   (Section 11) as used in
   WebDAV are described in section 11. WebDAV.  Since some WebDAV methods may
   operate over many resources, the Multi-Status response (Section 12)
   has been introduced to return status information for multiple
   resources.  The
   Multi-Status  Finally, this version of WebDAV introduces XML elements
   in error response is described bodies in section 12.

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                         WebDAV (RFC2518) bis             October 2003 Section 15.

   WebDAV uses XML [11] to marshal complicated request and response
   information, as well as to express metadata. metadata, so this specification
   contains definitions of all XML elements used in
   this specification are defined in section 13. Section 15 explains (Section 13).  WebDAV
   includes a few special rules on how to process  XML (Section 16)
   appearing in WebDAV so that it truly is extensible.

   WebDAV employs the property mechanism to store information about the
   current state of the resource.  For example, when a lock is taken out
   on a resource, a lock information property describes the current
   state of the lock.

   Finishing off the specification are sections on what it means to be
   compliant with this specification (section 16), (Section 17), on
   internationalization support (section 17), (Section 18), and on security (section
   18).

2 (Section
   19).

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], RFC2616 [8],
   including the rules about implied linear white-space.  Since this
   augmented BNF uses the basic production rules provided in section 2.2
   of [RFC2616], RFC2616 [8], 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 RFC 2119
   [RFC2119].

3 RFC2119 [3].

3.  Terminology

   URI/URL - A Uniform Resource Identifier and Uniform Resource Locator,
   respectively.  These terms (and the distinction between them) are
   defined in [RFC2396]. RFC2396 [6].

   Collection - A resource that contains a set of URLs, which identify
   and locate member resources and which meet the collections
   requirements in
   section 5 of this specification. (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 in section 5.2).

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   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 "getcontentlength" property 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.

4

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  Existing Metadata Proposals

   Properties have long played an essential role in the maintenance of
   large document repositories, and many current proposals contain some
   notion of a property, or discuss web metadata more generally.  These
   include PICS [REC-PICS], [20], PICS-NG, XML, Web Collections, and several
   proposals on representing relationships within HTML.  Work on PICS-NG
   and Web Collections has been subsumed by the Resource Description
   Framework (RDF) metadata activity of the World Wide Web Consortium.

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   RDF consists of a network-based data model and an XML representation
   of that model.

   Some proposals come from a digital library perspective.  These
   include the Dublin Core [RFC2413] metadata set and the Warwick
   Framework [WF], a container architecture for different metadata
   schemas.  The literature includes many examples of metadata,
   including MARC [USMARC], a bibliographic metadata format, and a
   technical report bibliographic format employed by the Dienst system
   [RFC1807].  Additionally, the proceedings from the first IEEE
   Metadata conference describe many community-specific metadata sets.

   Participants of the 1996 Metadata II Workshop in Warwick, UK [WF],
   noted that "new metadata sets will develop as the networked
   infrastructure matures" and "different communities will propose,
   design, and be responsible for different types of metadata." These
   observations can be corroborated by noting that many community-
   specific sets of metadata already exist, and there is significant
   motivation for the development of new forms of metadata as many
   communities increasingly make their data available in digital form,
   requiring a metadata format to assist data location and cataloging.

4.3  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.

4.4  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 Extensible Markup Language (XML) [REC-XML] XML [11] 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
   encode the responses from methods, providing the extensibility and
   internationalization advantages of XML for method output, as well as
   input.

   The XML namespace extension [10] 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

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   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:” "DAV:" is a scheme name defined solely to provide a
   namespace for WebDAV XML elements and property names.  This practice
   is discouraged in part because registration of new scheme names is
   difficult.  "DAV:" was defined as the WebDAV namespace before
   standard best practices emerged, and this namespace is kept and still
   used because of significant existing deployments, but this should not
   be emulated.

4.5  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 will 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.

   A property is always represented in XML with an XML element
   consisting of the property name.  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.  When the property value contains
   further XML elements, namespaces that are in scope for that part of
   the XML document apply within the property value as well, and MUST be
   preserved in server storage for retransmission later.  Namespace
   prefixes need not be preserved due to the rules of prefix declaration
   in XML.

   Attributes on the property name element may convey information about
   the property, but are not considered part of the value.  However,

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   when language information appears in the 'xml:lang' attribute on the
   property name element, the language information MUST be preserved in
   server storage for retransmission later.

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

4.6  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 [RFC2396], [6], 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
   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.

5

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.

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   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.

   Neither HTTP/1.1 nor WebDAV require that the entire HTTP URL
   namespace be consistent.  However, certain WebDAV methods are
   prohibited from producing results that cause namespace
   inconsistencies.

   Although implicit in [RFC2616] RFC2616 [8] and [RFC2396], RFC2396 [6], 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
   [RFC2396].
   RFC2396 [6].

   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
   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 http://
   example.com/bar/blah may or may not be an internal member of the
   collection with URL http://example.com/bar/.

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   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.bar/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.bar/blah/.  Wherever a server produces a URL
   referring to a collection, the server MUST include the trailing
   slash.  In general clients SHOULD use the "/" form of collection
   names.

   A resource MAY be a collection but not be WebDAV compliant.  That is,
   the resource may comply with all the rules set out in this
   specification regarding how a collection is to behave without
   necessarily supporting all methods that a WebDAV compliant resource
   is required to support.  In such a case the resource may return the
   DAV:resourcetype property with the value DAV:collection but MUST NOT
   return a DAV header containing the value "1" on an OPTIONS response.

   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/" "http://example.com/
   servlet/dav/" or its parent necessarily are WebDAV collections.

5.3  Source Resources and Output Resources

   For many resources, the entity returned by a GET method exactly
   matches the persistent state of the resource, for example, a GIF file
   stored on a disk.  For this simple case, the URL at which a resource
   is accessed is identical to the URL at which the source (the
   persistent state) of the resource is accessed.  This is also the case
   for HTML source files that are not processed by the server prior to
   transmission.

   However, the server can sometimes process HTML resources before they
   are transmitted as a return entity body.  For example, a server-
   side-include directive within an HTML file might instruct a server to
   replace the directive with another value, such as the current date.
   In this case, what is returned by GET (HTML plus date) differs from
   the persistent state of the resource (HTML plus directive).
   Typically there is no way to access the HTML resource containing the
   unprocessed directive.

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                         WebDAV (RFC2518) bis             October 2003

   Sometimes the entity returned by GET is the output of a data-
   producing process that is described by one or more source resources
   (that may not even have a location in the URI namespace).  A single
   data-producing process may dynamically generate the state of a
   potentially large number of output resources.  An example of this is
   a CGI script that describes a "finger" gateway process that maps part
   of the namespace of a server into finger requests, such as
   http://finger.example.com/finger_gateway/user@host. http://
   finger.example.com/finger_gateway/user@host.

   Although this problem would usefully be solved, interoperable WebDAV
   implementations have been widely deployed without actually solving
   this problem.  Thus, the source vs.  output problem is not solved in
   this specification, and has been deferred to a separate document.

6

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 (see (Section 7.5).  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 get 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

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                         WebDAV (RFC2518) bis             October 2003 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.

   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.

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6.3  Lock Tokens

   A lock token is a type of state token, represented as a URI, which
   identifies a particular lock.  A lock token is returned in the Lock-
   Token header in the response to a successful LOCK operation.  The
   lock token also appears in the value of the lockdiscovery property,
   the value of which is returned in the body of the response to a
   successful LOCK operation (this property also includes the tokens of
   other current locks on the resource).  Finally, the lockdiscovery
   property can be queried using PROPFIND and the token can be
   discovered that way.  Each lock has only one unique lock token.

   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.

   This specification provides a lock token URI scheme called
   opaquelocktoken that meets the uniqueness requirements.  However
   resources are free to return any URI scheme so long as it meets the
   uniqueness requirements.  The IETF recommends using registered URI
   schemes to ensure uniqueness.

   Having a lock token provides no special access rights.  Anyone can
   find out anyone else's lock token by performing lock discovery.
   Locks MUST be enforced based upon whatever authentication mechanism
   is used by the server, not based on the secrecy of the token values.

6.4  opaquelocktoken Lock Token URI Scheme

   The opaquelocktoken URI scheme is designed to be unique across all
   resources for all time.  Due to this uniqueness quality, a client may
   submit an opaque lock token in an If header on a resource other than
   the one that returned it.

   In order to guarantee uniqueness across all resources for all time
   the opaquelocktoken requires the use of the Universal Unique
   Identifier (UUID) mechanism, as described in [ISO-11578]. ISO-11578 [12].

   Opaquelocktoken generators, however, have a choice of how they create
   these tokens.  They can either generate a new UUID for every lock
   token they create or they can create a single UUID  and then add
   extension characters.  If the second method is selected then the
   program generating the extensions MUST guarantee that the same
   extension will never be used twice with the associated UUID.

   OpaqueLockToken-URI = "opaquelocktoken:" UUID [Extension]  ; The UUID
   production is the string representation of a UUID, as defined in [ISO-11578].
   ISO-11578 [12].  Note that white space (LWS) is not allowed between
   elements of this production.

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                         WebDAV (RFC2518) bis             October 2003

   Extension = path  ; path is defined in section 3.3 of [RFC2396] RFC2396 [6]

6.5  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 supportedlock property.

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

6.6  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 lockdiscovery
   property is provided.  This property lists all outstanding locks,
   describes their type, and where available, provides their lock token.

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

6.7 Usage Considerations  Avoiding Lost Updates

   Although the locking mechanisms specified here 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.

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                         WebDAV (RFC2518) bis             October 2003

   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

6.8  Locks and Multiple Bindings

   A resource may be made available through more than one URI.  However
   locks apply to resources, not URIs.  Therefore a LOCK request on a
   resource MUST NOT succeed if can not be honored by all the URIs
   through which the resource is addressable.

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.

   Write locks prevent unauthorized changes to resources.  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  Methods Restricted by Write Locks

   A write lock MUST prevent a principal without the lock from
   successfully executing a PUT, POST, PROPPATCH, LOCK, UNLOCK, MOVE,
   DELETE, or MKCOL on the locked resource.  All other current methods,
   GET in particular, function independently of the lock.

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

7.2  Write Locks and Lock Tokens

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   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.

7.3  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.

7.4  Write Locks and Unmapped URLs

   It is possible to lock an unmapped URL in order to lock 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.

   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.  In order to immediately lock a collection upon creation,
   clients may attempt to pipeline the MKCOL and LOCK requests together.

   A lock request to an unmapped URL SHOULD result in the creation of a an
   locked resource that is locked. with empty content.  A subsequent PUT request with
   the correct lock token SHOULD normally succeed, and this new request
   provides the content, content-type, content-language and other
   information as appropriate.

   In this situation, a WebDAV server that was implemented from RFC2518
   MAY create "lock-null" resources which are special and unusual
   resources.  Historically, a lock-null resource:

   -

   o  Responds with a 404 or 405 to any DAV method except for PUT,
      MKCOL, OPTIONS, PROPFIND, LOCK, UNLOCK.
   -
   o  Appears as a member of its parent collection.
   -
   o  Disappears (URI becomes unmapped) if its lock goes away before it
      is converted to a regular resource.  (This must also happen if it
      is renamed or moved, or if any parent collection is renamed or
      moved, because locks are tied to URLs).
   -
   o  May be turned into a regular resource when a PUT request to the
      URL is successful.  Ceases to be a lock-null resource.
   -
   o  May be turned into a collection when a MKCOL request to the URL is
      successful.  Ceases to be a lock-null resource

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                         WebDAV (RFC2518) bis             October 2003

   - resource.
   o  Has defined values for lockdiscovery and supportedlock properties.

   However, interoperability and compliance problems have been found
   with lock-null resources.  Therefore, they are deprecated.  WebDAV
   servers SHOULD create regular locked empty resources, which are and
   behave in every way as normal resources.  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)
   -
   o  SHOULD default to having no content type.
   -
   o  MAY NOT have values for properties like getcontentlanguage which
     haven’t
      haven't been specified yet by the client.
   -

   o  May have content added with a PUT request.  MUST be able to change
      content type.
   -
   o  MUST NOT be turned into a collection.  A MKCOL request must fail
      as it would to any existing resource.
   -
   o  MUST have defined values for lockdiscovery and 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 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
   deprecated lock-null resources and servers that support simpler
   locked empty resources by only attempting PUT after a LOCK to an
   unmapped URL, not MKCOL or GET.

7.5  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.

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                         WebDAV (RFC2518) bis             October 2003

   A zero-depth lock on a collection affects changes to the direct
   membership of that collection.  When a principal issues a PUT or POST
   request to create a new resource in a write locked collection, or
   issues a DELETE to remove a resource which has a URL which is an existing internal member URL of a write locked
   collection, this request MUST fail if the principal does not provide
   the correct lock token for the locked collection.

   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. code, and the response SHOULD
   contain the 'missing-lock-token' 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.

7.6  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 AČ”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

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   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.

   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>
            (<opaquelocktoken: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.

7.7  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, the resource is subject
   to being added to an existing lock at the destination, as specified
   in section 7.5. destination (see Section
   7.5).  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

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                         WebDAV (RFC2518) bis             October 2003 that is
   within the scope of the same lock (e.g., within the 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 Section 7.6, an If
   header must be submitted containing a lock token for both the source
   and destination.

7.8  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.

8

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 [REC-XML] XML [11] and [REC-XMLNS]. XML Namespaces [10].
   All XML used in either requests or responses MUST be, at minimum,
   well formed and use namespaces correctly.  If a server receives non-
   wellformed XML in a request it MUST reject the entire request with a
   400 (Bad Request).  If a client receives ill-formed XML in a response
   then it MUST NOT assume anything about the outcome of the executed
   method and SHOULD treat the server as malfunctioning.

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

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                         WebDAV (RFC2518) bis             October 2003 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  Use of Location header in responses

   When the Location header is used in a response, it is used by the
   server to indicate the preferred address for the target resource of
   the request.  Whenever the server has a preferred address, it should
   use that address consistently.  This means that when a response
   contains a Location header, all the URLs in the response body (e.g.
   a Multi-Status) should be consistent (most importantly, should use
   the same host and port).

8.1.4  Required Response Headers: Date

   Note that HTTP 1.1 requires the Date header in all responses if
   possible.

8.1.5  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
   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,
   as well as provide the same value for the 'getetag' property.

   Because clients may be forced to prompt users or throw away changed
   content if the ETag changes, a WebDAV server MUST not change the ETag
   (or getlastmodified value) for a resource that has an unchanged body.
   The ETag represents the state of the body or contents of the
   resource.  There is no similar way to tell if properties have
   changed.

8.1.6  Including error response bodies

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                         WebDAV (RFC2518) bis             October 2003

   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]). RFC3253 [18]).  The 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 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, avoiding the confusion of who is allowed to
   define such new codes.  The codes used in this mechanism are XML
   elements in a namespace, 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 include a specific XML error code in
   a "DAV:error" response body element, when a specific XML error code
   is defined in this document.  The “DAV:error” Č¼DAV:errorČ« element may contain
   multiple elements describing specific errors.  For error conditions
   not specified in this document, the server MAY simply choose an
   appropriate numeric status and leave the response body blank.

        HTTP/1.1 403 Forbidden
        Content-Type: text/xml; charset="utf-8"
        Content-Length: xxxx

        <?xml version="1.0" encoding="utf-8" ?>
        <D:error xmlns:D="DAV:">
          <D:forbid-external-entities/>
        </D:error>

   In this specification, both the numeric and the XML error code are
   defined for some failure situations, in which case the XML error code
   must have the "DAV:" namespace, appear in the "error" root element,
   and be returned in a body with the numeric error code specified.

   Status codes are specified in this document with the convention of
   following the numeric error code with the XML error code. E.g.

     403/DAV:forbid-external-entities - response codes when the server
     refuses to accept external XML entities in XML request bodies.

8.2  PROPFIND

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   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 (Section
   13.25) 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
   "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 request:

    -

   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 RFC2518bis MUST
      support this feature.
    -
   o  Request property values for those properties defined in this
      specification plus dead properties, by using ‘allprop’ 'allprop' element
    -
   o  Request a list of names of all the properties defined on the
      resource, by using the ‘propname’ '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’ 'allprop' request.

   Note that ‘allprop’ 'allprop' does not return values for all live properties.
   WebDAV servers increasingly have expensively-calculated or lengthy
   properties (see [RFC3253] RFC3253 [18] and [TODO: ref ACL RFC when available]) RFC3744 [19]) 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 text/
   xml or application/xml that contains a multistatus XML element that
   describes the results of the attempts to retrieve the various

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   properties.  The multistatus contains one response element for each
   resource in the scope of the request (in no required order). order) or may be
   empty if no resources match the request.

   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.

   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 gives the
   URL of the resource on which the properties in the prop XML element
   are defined.  URLs for collections appearing in the results MUST end
   in a slash character.  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.

   A server enumerating the members of a collection using absolute URLs
   in a PROPFIND response MUST use a common prefix in those URLs, and
   that prefix MUST be the absolute URL used in the response to refer to
   the parent collection.

   Unless otherwise notified, clients may expect that the URL for the
   parent collection in the PROPFIND response will be the same URL that
   was used to refer to the parent collection in the PROPFIND request.
   Servers MAY use an alternate URL for the parent collection in a
   PROPFIND response, but in this case the server MUST include a
   Content-Location header whose value is the fully-qualified URL used
   by the server to refer to the parent collection in this response.

   Clients expect the fully-qualified URLs of members of a collection to
   have a common prefix which is the fully-qualified URL of the parent
   collection itself.

   URLs in a PROPFIND response body MAY be represented as fully-
   qualified URLs, in which case they must all contain the full parent
   collection URL (scheme, host, port, and absolute path).
   Alternatively, these URLs MAY be absolute paths (not containing
   scheme, host or port), but in this case they must all still contain
   the full parent collection path.

   If a server allows resource names to include characters that aren’t arenČ”t
   legal in HTTP URL paths, these characters must be URI-escaped on the
   wire.  For example, it is illegal to use a space character or double-
   quote in a URI [RFC2396]. [6].  URIs appearing in PROPFIND or PROPPATCH XML
   bodies (or other XML marshalling defined in this specification) are
   still subject to all URI rules, including forbidden characters.

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   Properties may be subject to access control.  In the case of allprop
   and propname, 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  Example - Retrieving Named Properties

      >>Request

        PROPFIND  /file HTTP/1.1
        Host: www.example.com
        Content-type: text/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>

      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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>

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           </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.

8.2.2  Example - Retrieving Named and Dead Properties

      >>Request

        PROPFIND /mycol/ HTTP/1.1
        Host: www.example.com
        Depth: 1
        Content-type: text/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/. 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.

8.2.3  Example - Using propname to Retrieve all Property Names

      >>Request

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

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

      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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/>

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               <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.

   Consistent with the previous example, resource
   http://www.example.com/container/ 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 schema.

8.2.4  PROPFIND Request Errors

   PROPFIND requests may also fail entirely, before the server even gets
   a chance to evaluate individual properties.  404 (Not Found) and 401
   (Unauthorized) are possible as with every request.  These are some
   other notable errors.

   403/DAV:propfind-infinite-depth-forbidden

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

8.3  PROPPATCH

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   The PROPPATCH method processes instructions specified in the request
   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 sections 13.23 and section 13.24.

8.3.1  Status Codes for use with 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 command succeeded.  As there can be a mixture of sets
   and removes in a body, a 201 (Created) seems inappropriate.

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

   403/DAV:read-only-property:

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

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

   423 (Locked) - The specified resource is locked and the client either
   is not a lock owner or the lock type requires a lock token to be
   submitted and the client did not submit it.  This response SHOULD
   contain the 'missing-lock-token' precondition element.

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

8.3.2  Example - PROPPATCH

      >>Request

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        PROPPATCH /bar.html HTTP/1.1
        Host: www.example.com
        Content-Type: text/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>
      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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>

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   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 resource identified by the Request-URI is
   non-null 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.

   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 behavior of
   a MKCOL request when the body is present is 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.  The exact behavior of MKCOL for various
   request media types is undefined in this document, and will be
   specified in separate documents.

8.4.1  MKCOL Status Codes

   Responses from a MKCOL request MUST NOT be cached as MKCOL has non-
   idempotent semantics.

   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

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   location in its 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 type of the body.

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

8.4.1

8.4.2  Example - MKCOL

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

      >>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

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   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

8.7.1  DELETE for Non-Collection Resources

   When a client issues a DELETE request to a Request-URI mapping to a
   non-collection resource, if the operation is successful the server
   MUST remove that mapping.  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).

8.7.2  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
   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 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 Multi-
   Status, if the entire DELETE request failed and it can’t canČ”t identify
   the internal resources that caused the DELETE to fail.

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   424 (Failed Dependency) errors SHOULD NOT be in the 207 (Multi-
   Status).  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.

8.7.1

8.7.3  Example - DELETE

      >>Request

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

      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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 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

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                         WebDAV (RFC2518) bis             October 2003 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

   As defined in [RFC2616], RFC2616 [8], the "PUT method requests that the enclosed
   entity be stored under the supplied Request-URI."  Since submission
   of an entity representing a collection would implicitly encode
   creation and deletion of resources, this specification intentionally
   does not define a transmission format for creating a collection using
   PUT.  Instead, the MKCOL method is defined to create collections.

8.9  COPY Method

   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 HTTP/1.1 resources 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,

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                         WebDAV (RFC2518) bis             October 2003 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.  If a property cannot be copied live, then its value MUST be
   duplicated, octet-for-octet, in an identically named, dead property
   on the destination resource.

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

8.9.1

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.

   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 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 namespace at the destination (see section 5.1 for Section 8.7.2for 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).

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   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/. /
   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
   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.

8.9.2

8.9.4  COPY and the Overwrite Header

   If a resource exists at the destination and the Overwrite header is
   "T" then prior to performing the copy 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.

8.9.3

8.9.5  Status Codes

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

   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.  Possibly this is
   because 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.

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   412 (Precondition Failed) - A precondition failed, e.g.  the
   Overwrite header is "F" and the state of the destination resource is
   non-null.

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

   502 (Bad Gateway) - This may occur when the destination is on another
   server, repository or 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.

8.9.4   Example -

8.9.6  COPY with Overwrite Examples

   This example shows resource
   http://www.ics.uci.edu/~fielding/index.html http://www.ics.uci.edu/~fielding/
   index.html being copied to the location http://www.ics.uci.edu/users/f/fielding/index.html. 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.

   COPY with Overwrite

      >>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

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 resource
   has a non-null state.

   COPY with No Overwrite

      >>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

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                         WebDAV (RFC2518) bis             October 2003

      >>Response

        HTTP/1.1 412 Precondition Failed

   Example - COPY of a Collection

      >>Request

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

      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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 Method

   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

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                         WebDAV (RFC2518) bis             October 2003
   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.

8.10.1  MOVE for Properties

   Live properties described in this document MUST 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.  If the live properties will not work the same way at
   the destination, the server MUST fail the request (the client can
   perform COPY then DELETE if it wants a MOVE to work that badly).
   This can mean that the server reports the live property as "Not
   Found" if that's the most appropriate behavior for that live property
   at the destination, as long as the live property is still supported
   with the same semantics.

   MOVE is frequently used by clients to rename a file without changing
   its parent collection, so it's not appropriate to reset live
   properties which are set at resource creation.  For example, the
   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.

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                         WebDAV (RFC2518) bis             October 2003
   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 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).  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

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

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

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   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) – - The source 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
   'live-properties-not-preserved' postcondition).

   412 (Precondition Failed) – Ș A condition failed, e.g.  the Overwrite
   header is "F" and the state of the destination resource is non-null.

   423 (Locked) - The source or the destination resource, or some
   resource within the source or destination collection, was locked.

   500/DAV:live-properties-not-preserved - The server was unable to
   preserve the behavior of the live properties and still move the
   resource to
   This response SHOULD contain the destination. 'missing-lock-token' precondition
   element.

   502 (Bad Gateway) - This may occur when the destination is on another
   server and the destination server refuses to accept the resource.

8.10.5  Example - MOVE
   This could also occur when the destination is on another sub-section
   of a Non-Collection the same server namespace.

8.10.5  Examples

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

   MOVE of a Non-Collection

      >>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

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                         WebDAV (RFC2518) bis             October 2003

Example -

   MOVE of a Collection

      >>Request

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

      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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/. 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 /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.

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                         WebDAV (RFC2518) bis             October 2003

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

Operation

   A LOCK method invocation to an unlocked resource creates the a lock specified by the lockinfo
   XML element on
   the resource indicated 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" 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.  The response
   MUST contain the value of the lockdiscovery property in a prop XML
   element.

   In order

   A success response to indicate the lock token associated with a newly created
   lock, a Lock-Token response header MUST be included in the response
   for every successful LOCK request for a new lock.  Note that MUST include the Lock-Token header would not be returned in the
   response for a
   successful refresh LOCK request because a new lock was not created.

Refreshing Locks

   A lock is refreshed by sending a new LOCK request to the resource
   which is the root of the lock. A LOCK request to refresh a lock 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).  This
   request does not contain a body, but it may contain a Timeout
   header.  A server MAY accept the Timeout header to change the
   duration remaining on the lock to the new value.

   If the resource has other (shared) locks, those locks are unaffected
   by a lock refresh.  Additionally, those locks do not prevent token associated with the
   named lock from being refreshed. new lock, and MUST
   contain a body with the value of the 'lockdiscovery' property.  Note
   that in RFC2518, clients were indicated through the example Lock-Token header would not be returned in the text to use the If header to specify what lock to response for
   a successful refresh
   (rather than the Lock-Token header). Servers are encouraged to
   continue to support this as well as the Lock-Token header.

The Effect of Locks on Properties and Collections

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                         WebDAV (RFC2518) bis             October 2003 LOCK request because a new lock was not created.

   The scope of a lock is the entire state of the resource, including
   its body and associated properties.  As a result, a lock on a
   resource MUST also lock the resource's properties.

   For collections, a lock also affects the ability to add or remove
   members.  The nature of the effect depends upon the type of access
   control involved.  This means that if a collection is locked, its
   lock-token is required in all these cases:
    -

   o  DELETE a collection’s collection's direct internal member
    -
   o  MOVE a member out of the collection
    -
   o  MOVE a member into the collection, unless it overwrites a pre-
      existing member
    -
   o  MOVE to rename it within a collection,
    -
   o  COPY a member into a collection, unless it overwrites a pre-
      existing member
    -
   o  PUT or MKCOL request which would create a new member.
   The collection’s lock token is required in addition to new member.

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

   The interaction of a LOCK with various methods is dependent upon the
   lock type.  However, independent of lock type, a successful DELETE of
   a resource MUST cause all of its direct locks to be removed.

8.11.1  Refreshing Locks

   A lock is refreshed by sending a LOCK request without a body to a
   resource within the scope of the lock.  A LOCK request to refresh a
   lock 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).  This request MUST NOT contain a body, but it may contain a
   Timeout header.  A server MAY accept the Timeout header to change the
   duration remaining on the lock to the new value.  A server MUST
   ignore the Depth header on a LOCK refresh, and the client SHOULD NOT
   send the Depth header on a LOCK refresh as the server will not
   convert the lock
   token on or confirm the depth.

   If the internal member itself, if it exists.

Locking Replicated Resources

   A resource may be made available through more than one URI. However has other (shared) locks, those locks apply to resources, not URIs. Therefore a LOCK request on are unaffected
   by a
   resource MUST NOT succeed if can lock refresh.  Additionally, those locks do not be honored by all prevent the URIs
   named lock from being refreshed.

   Note that in RFC2518, clients were indicated through which the resource is addressable. 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.

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.  If the lock cannot be granted to
   all resources, a 409 (Conflict) 207 (Multi-Status) status code MUST be returned with
   a response entity body containing a multistatus XML element
   describing which resource(s) prevented the lock from being granted.
   Hence, partial success is not an option.  Either the entire hierarchy
   is locked or no resources are locked.

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

Interaction with other Methods

   The interaction of a LOCK with various methods is dependent upon the
   lock type.  However, independent of lock type, a successful DELETE
   of a resource MUST cause all of its direct locks to be removed.

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.

        Current State   Shared Lock Request   Exclusive Lock Request
      --------------------------------------------------------------------
        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.

Status Codes

8.11.5  LOCK responses

   200 (OK) - The lock request succeeded and the value of the
   lockdiscovery property is included in the body.

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   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) - The included lock token was not
   enforceable on this resource or the server could not satisfy satisfy the
   request in the lockinfo XML element.

   423 (Locked) - The resource is locked already.  For consistency's
   sake, this response SHOULD contain the 'missing-lock-token'
   precondition element.

   400 (Bad Request), with 'request-uri-must-match-lock-token'
   precondition - 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 in Request-URI, or the lockinfo XML element.

   423 (Locked) - The resource is locked, so lock could have disappeared, or the method has been
   rejected.

8.11.1
   token may be invalid.

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: text/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>

      >>Response

        HTTP/1.1 200 OK
        Lock-Token: <opaquelocktoken:e71d4fae-5dec-22d6-fea5-00a0c91e6be4>
        Content-Type: text/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>

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             <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>opaquelocktoken: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.

   Note that the locktoken and lockroot href elements would not contain
   any whitespace.  The line return appearing in this document is only
   for formatting.

8.11.2

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: <opaquelocktoken:e71d4fae-5dec-22d6-fea5-00a0c91e6be4>
        Authorization: Digest username="ejw",
           realm="ejw@example.com", nonce="...",
           uri="/workspace/webdav/proposal.doc",
           response="...", opaque="..."

      >>Response

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        HTTP/1.1 200 OK
        Content-Type: text/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>opaquelocktoken: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.

8.11.3

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: text/xml; charset="utf-8"
        Content-Length: xxxx
        Authorization: Digest username="ejw",

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           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: text/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:propstat>
             <D:prop><D:lockdiscovery/></D:prop>
             <D:status>HTTP/1.1 424 Failed Dependency</D:status>
           </D:propstat>
         </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
   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. http://
   example.com/webdav/secret.  Because this resource could not be
   locked, none of the resources were locked.  Note also that the
   lockdiscovery property for the Request-URI has been included as

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   required.  In this example the lockdiscovery property is empty which
   means that there are no outstanding locks on the resource.

   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 from the Request-URI and all other
   resources included in the lock. header.  The root of the lock Request-URI MUST be named
   by the Request-URI, not any other identify a
   resource within the scope of the lock.  Servers SHOULD redirect the UNLOCK request  The If header is not needed
   to provide the lock root.
   Failing that, token although servers MAY fail an UNLOCK request to SHOULD still evaluate the
   If header and treat it as a conditional header.

   For a successful response to this method, the server MUST remove the
   lock from the resource that
   is not directly locked (not identified by the root of Request-URI and from all
   other resources included in the lock) with error code
   400 (Bad Request). 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

   204 (No Content) – - Normal success response

   400 (Bad Request) – - No lock token was provided, provided (see
   'missing-lock-token' precondition), or request was not made to a
   Request-URI that was not within the scope of the lock (see
   'requesturi-must-match-lock-token' precondition).

   403 (Forbidden) - The currently authenticated principal does not have
   permission to remove the lock root. (the server SHOULD use the
   'need-privileges' precondition element).

   412 (Precondition Failed) - The resource was not locked.

8.12.1

8.12.2  Example - UNLOCK

      >>Request

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

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      >>Response

        HTTP/1.1 204 No Content

   In this example, the lock identified by the lock token
   "opaquelocktoken:a515cfa4-5da4-22e1-f5b5-00a0451e6bf7" is
   successfully removed from the resource
   http://example.com/workspace/webdav/info.doc. 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.

9

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.

9.1  DAV Header

      DAV             = "DAV" ":" #( compliance-code )
      compliance-code = ( "1" | "2" | "bis" | extend )
      extend          = Coded-URL | token

   As a

   This general-header appearing in the response header, this header indicates that the
   resource supports the DAV schema and protocol as specified.  All DAV
   compliant resources MUST return the DAV header 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

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   means that the repository supports the named features in at least
   some internal namespaces.

   As an optional request header, this header allows the client to
   advertise compliance with named features.  Clients need not advertise
   1, 2 or bis because a WebDAV server currently doesn't need that
   information to decide how to respond to requests defined in this
   specification or in HTTP/1.1.  However, future extensions may define
   client compliance codes.  When used as a request header, the DAV
   header MAY affect caching so this header SHOULD NOT be used on all
   GET requests.

9.2  Depth Header

      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

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   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.

   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" ":" ( absoluteURI | abs_path )

   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 absoluteURI and abs_path
   production are defined in [RFC2396].  If abs_path is used, the
   scheme, host and port of the destination are the same as those for
   the Request-URI (note the Host header, which must be present on
   requests, contains
   two URIs as parameters.  Note that the host and port). absoluteURI production is
   defined in RFC2396 [6].

   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.  Servers MAY attempt to copy the resource
   to the remote server using PUT/PROPPATCH or another mechanism.

9.4  Force-Authentication Header

   Force-Authentication = "Force-Authentication" ":" Method

   The Force-Authentication request header is used with the OPTIONS
   method to specify that the client wants to be challenged for
   authentication credentials to the resource identified by the
   Request-URI.  If present on a request to a WebDAV-compliant resource,
   the server MUST respond with either 401 (Unauthorized) or 501 (Not
   Implemented)

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   indicate what method it intends to use first on the resource
   identified in the Request-URI.

9.5  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 List | "[" entity-tag "]")) Clause ")" )
      Clause = ["Not"] State-token | State-token
      State-token = Coded-URL  | "[" entity-tag "]"
      Coded-URL = "<" absoluteURI ">"

   The If request header is intended to have similar functionality to
   the If- Match header defined in section 14.24 of [RFC2616]. RFC2616 [8].
   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 a special token that
   must never match an actual valid lock token.  The purpose of this is
   described in section 9.5.5.

   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 parse the If header when it appears on any request,
   evaluate all the clauses, and if the conditional evaluates to false,
   fail the request.

   Note that the absoluteURI production is defined in [RFC2396]. RFC2396 [6].

   RFC2518 originally defined the If header without comma separators.
   This oversight meant that the If header couldn't be divided up among
   multiple lines according to the HTTP header manipulation rules.
   Servers supporting "bis" MUST be able to accept commas in If header
   values.  If the header has commas between tokens or clauses, the
   header can be evaluated simply by removing the commas and proceeding
   with the evaluation rules.

9.5.1  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

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   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.

9.5.2

   Example - No-tag-list If Header no-tag-list production

        If: (<opaquelocktoken:a-write-lock-token> ["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
   <opaquelocktoken:a-write-lock-token> ["I am an ETag"]) (and ["I am
   another ETag"])).

9.5.3

9.5.2  Tagged-list Production

   The tagged-list production scopes a list production.  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.

9.5.4

   Example - Tagged List If header

        COPY /resource1 HTTP/1.1
        Host: www.example.com
        Destination: http://www.example.com/resource2
        If: <http://www.example.com/resource1> (<locktoken:a-write-lock-
        token> [W/"A weak ETag"]), (["strong ETag"]),
        <http://www.bar.bar/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 "(<locktoken:a-write-lock-token> [W/"A weak ETag"])
   (["strong ETag"])", that is, it either must be locked with a lock
   token of "locktoken:a-write-lock-token" and have a weak entity tag
   W/"A 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.bar.bar/random http://
   www.bar.bar/random never has the method applied to it (the

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   resource listed in the If header) and
   http://www.example.com/resource2 http://www.example.com/
   resource2 is not listed in the If header.

9.5.5

9.5.3  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’ "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 <locktoken:write1> <locktoken:write2>)

   When submitted with a request, this If header requires that all
   operand resources must not be locked with locktoken:write1 and must
   be locked with locktoken:write2.

   The Not production is particularly useful with the "<DAV:no-lock>"
   state token.  The clause "Not <DAV:no-lock>" must evaluate to true.
   Thus, any "OR" statement containing the clause "Not <DAV:no-lock> <DAV:no-lock>"
   must also evaluate to true.

9.5.6

9.5.4  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 that 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.

9.5.7  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/> (<locktoken:a-write-lock-token>)

   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.

9.5.5  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.

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9.6  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.

9.7  Overwrite Header

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

   The Overwrite request header specifies whether the server should
   overwrite the state of a non-null destination resource 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 resource is
   non-null.  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.

   All DAV compliant resources MUST support the Overwrite header.

9.8  Timeout Request Header

      TimeOut = "Timeout" ":" 1#TimeType
      TimeType = ("Second-" DAVTimeOutVal | "Infinite")
      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.

   The "Second" TimeType specifies the number of seconds that will
   elapse between granting of the lock at the server, and the automatic

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   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).

10

10.  Status Code Extensions to HTTP/1.1

   The following status codes are added to those defined in HTTP/1.1
   [RFC2616].
   RFC2616 [8].

10.1  102 Processing

   The 102 (Processing) status code is an interim response used to
   inform the client that the server has accepted the complete request,
   but has not yet completed it.  This status code SHOULD only be sent
   when the server has a reasonable expectation that the request will
   take significant time to complete.  As guidance, if a method is
   taking longer than 20 seconds (a reasonable, but arbitrary value) to
   process the server SHOULD return a 102 (Processing) response.  The
   server MUST send a final response after the request has been
   completed.

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   Methods can potentially take a long period of time to process,
   especially methods that support the Depth header.  In such cases the
   client may time-out the connection while waiting for a response.  To
   prevent this the server may return a 102 (Processing) status code to
   indicate to the client that the server is still processing the
   method.

10.2  207 Multi-Status

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

10.3  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.

10.4  423 Locked

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

10.5  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).

10.6  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.

11

11.  Use of HTTP Status Codes

11.1  301 Moved Permanently

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   Any WebDAV request may be redirected using this status code.

11.2  302 Found

   Any WebDAV request may be redirected using this status code.

11.3  400 Bad Request

   This code may be used if:
    -

   o  the Host header is missing in any request
    -
   o  The protocol version is HTTP/1.0
    -
   o  Any header is improperly formatted
    -
   o  The request method line is improperly formatted

11.4  403 Forbidden

   Uses:
    - The

   To be used if the server does not ever accept this method on this
   kind of resource.  For example, if a PUT is not accepted on a
   collection.

11.5  409 Conflict

   The 409 Conflict is most typically returned when a method that
   attempts to create a new resource must fail, because one of the
   collections that resource depends on does not exist.  However, other
   types of conflicts are defined in specifications extending RFC2518.
   Therefore, this can be returned in response to all methods.

11.6  414 Request-URI Too Long

   This status code is used in HTTP 1.1 only for Request-URIs, because
   full URIs aren’t arenČ”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.  This status code may be used in
   response to any method in this specification.

12

12.  Multi-Status Response

   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.

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   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.  URLs for
   collections appearing in the results SHOULD end in a ‘/’ '/' character.

   When a Multi-Status body is returned in response to a PROPFIND or
   another request with a single scope, all URLs appearing in the body
   must be equal to or inside the request-URI, thus the URLs MAY be
   absolute or MAY be relative.
    -

   o  If the URLs are absolute, then the server MUST ensure that the
      URLs have the same prefix (scheme, host, port, and path) as the
      URL of the requested resource (which may be the same as the
      Request-URI or may be the corrected in the response Location
      header).
    -
   o  If the URLs are relative, they MUST be resolved against the
      Location header, if present, or as second choice against the
      Request-URI.

   When a Multi-Status body is returned in response to MOVE or COPY,
   relative URIs resolution is ambiguous (the request had both a source
   and a destination URL).  Thus, URLs appearing in the responses to
   MOVE or COPY SHOULD be absolute and fully-qualified URLs.

12.1  Responses requiring Location in Multi-Status

   The 300-303, 305 and 307 responses defined in HTTP 1.1 normally take
   a Location header to indicate where the client should make the
   request.  The Multi-Status response syntax as defined in RFC2518 did
   not allow for the Location header information to be included in an
   unambiguous way, so servers MAY choose not to use these status codes
   in Multi-Status responses.  If a clients receives this status code in
   Multi-Status, the client MAY reissue the request to the individual
   resource, so that the server can issue a response with a Location
   header for each resource.

   Additionally, this specification defines a new element that servers
   MAY use in the response element to provide a location value in
   Multi-Status (see section Section 13.29).

13

13.  XML Element Definitions

   In the section below, this section, the final line of each section gives the element
   type declaration using the format defined in [REC-XML]. XML [11].  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

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   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.

13.1  activelock XML Element

   Name:  activelock
   Namespace:  DAV:
   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  depth XML Element

   Name:  depth
   Namespace:  DAV:
   Purpose:  The value of the Depth header.
   Value:  "0" | "1" | "infinity"
   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT depth (#PCDATA) >

13.3  locktoken XML Element

   Name:  locktoken
   Namespace:  DAV:
   Purpose:  The lock token associated with a lock.
   Description:  The href contains a single lock token URI which refers
      to the lock (i.e., the OpaqueLockToken-URI production in section
      6.4).
   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT locktoken (href) >

13.4  lockroot XML Element

   Name:  lockroot
   Namespace:  DAV:
   Purpose:  Contains the root URL of the lock, which is the URL of through
      which the resource that was addressed in the LOCK request.

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   Description:  The href contains a URL with the address of the root of
      the lock.  The server SHOULD include this in all lockdiscovery
      property values and the response to LOCK requests.
   Extensibility:  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT lockroot (href) >

13.5  timeout XML Element

   Name:  timeout
   Namespace:  DAV:
   Purpose:  The number of seconds remaining before a lock expires.
   Value:  TimeType (defined in section Section 9.8).
   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT timeout (#PCDATA) >

13.6  collection XML Element

   Name:  collection
   Namespace:  DAV:
   Purpose:  Identifies the associated resource as a collection.  The
      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 >

13.7  href XML Element

   Name:  href
   Namespace:  DAV:
   Purpose:  Identifies the content of the element as a URI.  In many
      situations, this URI MUST be a HTTP URI, and furthermore, it MUST
      identify a WebDAV resource.  There is one exception to this
      general rule in the lockdiscovery property, where the lock token
      (which is a URI but may not be a HTTP URI) is inside the href
      element.  Other specifications SHOULD be explicit if the href
      element is to contain non-HTTP URIs.
   Value:  URI (See section 3.2.1 of [RFC2616]) RFC2616 [8])
   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT href (#PCDATA)>

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13.8  lockentry XML Element

   Name:  lockentry
   Namespace:  DAV:
   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) >

13.9  lockinfo XML Element

   Name:  lockinfo
   Namespace:  DAV:
   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?)  >

13.10  lockscope XML Element

   Name:  lockscope
   Namespace:  DAV:
   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) >

13.11  exclusive XML Element

   Name:  exclusive
   Namespace:  DAV:
   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 >

13.12  shared XML Element

   Name:  shared

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   Namespace:  DAV:
   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 >

13.13  locktype XML Element

   Name:  locktype
   Namespace:  DAV:
   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) >

13.14  write XML Element

   Name:  write
   Namespace:  DAV:
   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 >

13.15  multistatus XML Element

   Name:  multistatus
   Namespace:  DAV:
   Purpose:  Contains multiple response messages.
   Description:
   Description The responsedescription 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?)  >

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13.16  response XML Element

   Name:    response  locktype
   Namespace:  DAV:
   Purpose:  Holds a single response describing the effect of a method
      on resource and/or its properties.
   Description:  A particular href 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?) >

13.17  propstat XML Element

   Name:  propstat
   Namespace:  DAV:
   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?) >

13.18  status XML Element

   Name:  status
   Namespace:  DAV:
   Purpose:  Holds a single HTTP status-line
   Value:  status-line (status-line defined in [RFC2616]) RFC2616 [8]
   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT status (#PCDATA) >

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13.19  responsedescription XML Element

   Name:  responsedescription
   Namespace:  DAV:
   Purpose:  Contains a message that can be displayed to the user
      explaining the nature of the response.
   Description:  This XML element provides information suitable to be
      presented to a user.
   Extensibility:  MAY be extended with attributes which SHOULD be
      ignored.

   <!ELEMENT responsedescription (#PCDATA) >

13.20  owner XML Element

   Name:  owner
   Namespace:  DAV:
   Purpose:  Provides information about the principal taking out a lock.
   Description:
   Description The owner XML element 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:
   Extensibility MAY be extended with child elements, mixed content,
      text content or attributes.  Structured content, for example one
      or more <href> child elements containing URLs, is RECOMMENDED.

   <!ELEMENT owner ANY

13.21  prop XML element

   Name:  prop
   Namespace:  DAV:
   Purpose:  Contains properties related to a resource.
   Description:
   Description The prop XML element is 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:

   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.

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   <!ELEMENT prop ANY

13.22  propertyupdate XML element

   Name:  propertyupdate
   Namespace:  DAV:
   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)+ >

13.23  remove XML element

   Name:  remove
   Namespace:  DAV:
   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  set XML element

   Name:  set
   Namespace:  DAV:
   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.  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.

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   <!ELEMENT set (prop) >

13.25  propfind XML Element

   Name:  propfind
   Namespace:  DAV:
   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 (prop | dead-props | propname | allprop) >

13.26  allprop XML Element

   Name:  allprop
   Namespace:  DAV:
   Purpose:  The allprop XML element 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 >

13.27  propname XML Element

   Name:  propname
   Namespace:  DAV:
   Purpose:  The propname XML element 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 >

13.28  dead-props XML Element
   Name:  dead-props

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   Namespace:  DAV:
   Purpose:  The dead-props XML element 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 >

13.29  location XML Element

   Name:  location
   Namespace:  DAV:
   Purpose:  In normal responses (not Multi-Status), some status codes
      go along with a Location header.  When these status codes are used
      in a Multi-Status response, this element is used instead.
   Description:  Contains a single href element with the same URI that
      would be used in a Location header.
   Extensibility: MAY be extended  MAY be extended with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT location (href) >

13.30  error XML Element

   Name:  error
   Namespace:  DAV:
   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' tag SHOULD
      include a standard error tag defined in this specification or
      another specification.  The 'error' tag MAY include custom error
      tags (in custom namespaces) which a client can safely ignore.
   Description:  Contains any XML element
   Extensibility:  Fully extensible with additional child elements or
      attributes which SHOULD be ignored if not recognized.

   <!ELEMENT (href) error ANY >

14

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 [REC-XML]. XML [11].  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.

   Some property values are calculated by the server and it is not
   appropriate to allow client changes, thus they are protected.
   Existing server implementations already have different sets of
   RFC2518 properties protected, but clients can have some expectations
   which properties are normally protected.  The value of a protected protected
   property may not be changed even by a user with permission to edit
   other properties.  The value of an unprotected property may be
   changed by some users with appropriate permissions.

14.1  creationdate Property

   Name:  creationdate
   Namespace:  DAV:
   Purpose:  Records the time and date the resource was created.
   Value:  date-time (defined in RFC3339 [9], see the ABNF in section
      5.6.)
   Protected:  MAY be protected.  Some servers allow 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 getetag instead).
   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 creationdate property should be defined on all DAV
      compliant resources.  If present, it contains a timestamp of the
      moment when the resource was created (i.e., the moment it had
      non-null state).
   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT creationdate (#PCDATA) >

14.2  displayname Property
   Name:  displayname
   Namespace:  DAV:
   Purpose:  Provides a name for the resource that is suitable for
      presentation to a user.
   Value:  Any text
   Protected:  Possibly
   COPY/MOVE behaviour:  This property value SHOULD be preserved in
      local COPY and MOVE operations.  It MAY be attempted to be set in
      a COPY operation to a remote server.
   Description:  The displayname property may not should be changed even by defined on all DAV
      compliant resources.  If present, the property contains a user with permission to edit
   other properties.  The value
      description of an unprotected property may the resource that is suitable for presentation to a
      user.
   Extensibility:  MAY contain attributes which SHOULD be
   changed by some users with appropriate permissions.

14.1    creationdate ignored if not
      recognized.

   <!ELEMENT displayname (#PCDATA) >

14.3  getcontentlanguage Property

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   Name:    creationdate  getcontentlanguage
   Namespace:  DAV:
   Purpose: Records the time and date  Contains the resource was created. Content-Language header returned by a GET
      without accept headers
   Value:   date-time (defined in [RFC3339], see the ABNF  language-tag (language-tag is defined in section
            5.6.) 14.13 of
      RFC2616 [8])
   Protected: MAY be protected.  Some servers allow creationdate to  SHOULD NOT be
            changed to reflect the time the document was created if protected, so 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 getetag instead). can reset the
      language.
   COPY/MOVE behaviour:  This property value SHOULD be kept during a preserved in
      local COPY and MOVE operation, but is normally re-initialized when operations.  It SHOULD be attempted to be set
      in a COPY operation to a remote server.
   Description:  The getcontentlanguage property MUST be defined on any
      DAV compliant resource is created with that returns the Content-Language header on
      a COPY. It should GET.
   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getcontentlanguage (#PCDATA) >

14.4  getcontentlength Property

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

   Value:  content-length (see section 14.14 of RFC2616 [8])
   Protected:  SHOULD be protected so clients cannot set in a
            COPY. to misleading
      values
   Description:  The creationdate getcontentlength property should MUST be defined on all any
      DAV compliant resources.  If present, it contains resource that returns the Content-Length header in
      response to a timestamp GET.
   COPY/MOVE behaviour:  This property value is dependent on the size of
      the moment when destination resource, not the resource was created (i.e., value of the
            moment it had non-null state). property on the
      source resource.
   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT creationdate getcontentlength (#PCDATA) >

14.2    displayname

14.5  getcontenttype Property

   Name:    displayname  getcontenttype
   Namespace:  DAV:
   Purpose: Provides a name for  Contains the resource that is suitable for
            presentation to Content-Type header returned by a user. GET without
      accept headers.
   Value: Any text  media-type (defined in section 3.7 of RFC2616 [8])
   Protected: Possibly  SHOULD NOT be protected, so clients may fix this value
   COPY/MOVE behaviour:  This property value SHOULD be preserved in
      local COPY and MOVE operations. It MAY be attempted to be
            set in  In a remote COPY operation to that
      is implemented through a remote server. PUT request, the PUT request must have
      the appropriate Content-Type header.
   Description:  The displayname  This getcontenttype property should MUST be defined on all any DAV
      compliant resources.  If present, the property contains a
            description of the resource that is suitable for
            presentation returns the Content-Type header in
      response to a user. GET.
   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT displayname getcontenttype (#PCDATA) >

14.3    getcontentlanguage

14.6  getetag Property

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   Name:    getcontentlanguage  getetag
   Namespace:  DAV:
   Purpose:  Contains the Content-Language ETag header returned by a GET without accept headers
      headers.
   Value:   language-tag (language-tag is defined  entity-tag  (defined in section 14.13 3.11 of
            [RFC2616]) RFC2616 [8])
   Protected: SHOULD NOT MUST be protected, so that clients can reset protected because this value is created and
      controlled by the
            language. server.
   COPY/MOVE behaviour:  This property value SHOULD be preserved in
            local COPY and MOVE operations. It SHOULD be attempted to
            be set in a COPY operation to a remote server. is dependent on the final
      state of the destination resource, not the value of the property
      on the source resource.

   Description:  The getcontentlanguage getetag property MUST be defined on any DAV
      compliant resource that returns the Content-Language
            header on Etag header.  Refer to RFC2616
      for a GET. complete definition of the semantics of an ETag.  Note that
      changes in properties or lock state MUST not cause a resourceȔs
      ETag to change.
   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getcontentlanguage getetag (#PCDATA) >

14.4    getcontentlength

14.7  getlastmodified Property

   Name:    getcontentlength  getlastmodified
   Namespace:  DAV:
   Purpose:  Contains the Content-Length Last-Modified header returned by a GET method
      without accept headers.
   Value:   content-length (see  HTTP-date  (defined in section 14.14 3.3.1 of [RFC2616]) RFC2616 [8])
   Protected:  SHOULD be protected so because some clients cannot set to misleading
            values
   Description: The getcontentlength property MUST be defined may rely on any
            DAV compliant resource that returns the Content-Length
      value for appropriate caching behavior, or on the value of the
      Last-Modified header in response to a GET. which this property is linked.
   COPY/MOVE behaviour:  This property value is dependent on the size last
      modified date 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) >

14.5    getcontenttype Property

   Name:    getcontenttype
   Namespace:   DAV:
   Purpose: Contains  Note that some server
      implementations use the Content-Type header returned by a GET without
            accept headers.

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   Value:   media-type (defined file system date modified value for the
      'getlastmodified' value, and this is preserved in section 3.7 of [RFC2616])
   Protected: a MOVE even when
      the HTTP Last-Modified value SHOULD NOT be protected, so change.  Thus, clients may fix cannot
      rely on this value
   COPY/MOVE behaviour: This property value SHOULD be preserved in
            local COPY for caching and MOVE operations. In a remote COPY operation SHOULD use ETags.
   Description:  Note that is implemented through the last-modified date on a PUT request, resource SHOULD
      only reflect changes in the PUT request
            must have 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 appropriate Content-Type header.
   Description:         This getcontenttype
      last-modified date to know when to overwrite the existing body.
      The getlastmodified property MUST be defined on any DAV compliant
      resource that returns the Content-Type Last- Modified header in response to a
      GET.
   Extensibility:  MAY contain attributes which SHOULD be ignored if not
      recognized.

   <!ELEMENT getcontenttype getlastmodified (#PCDATA) >

14.6    getetag

14.8  lockdiscovery Property

   Name:  lockdiscovery
   Namespace:  DAV:
   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:  The lockdiscovery property 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 Č½activelockČ” elements.  If there is one
      or more lock, an Č½activelockČ” 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: text/xml; charset="utf-8"

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

      >>Response

        HTTP/1.1 207 Multi-Status
        Content-Type: text/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>opaquelocktoken: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:    getetag  resourcetype
   Namespace:  DAV:
   Purpose: Contains  Specifies the ETag header returned by a GET without accept
            headers.
   Value:   entity-tag  (defined in section 3.11 nature of [RFC2616]) the resource.
   Protected: MUST  SHOULD be protected because this value protected.  Resource type is created and
            controlled by generally decided
      through the server. operation creating the resource (MKCOL vs PUT), not by
      PROPPATCH.
   COPY/MOVE behaviour: This property value is dependent on the final
            state  Generally a COPY/MOVE of a resource results in
      the destination resource, not the value same type of resource at the
            property on destination.  In a remote COPY,
      the source resource. server SHOULD NOT attempt to set this property.
   Description:  The getetag resourcetype property MUST be defined on any all 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. resources.  The default value is empty.
   Extensibility:  MAY contain be extended with any child elements or attributes
      which SHOULD be ignored if not recognized.

   <!ELEMENT getetag (#PCDATA) >

14.7    getlastmodified  If the element
      contains the 'collection' child element plus additional
      unrecognized elements/attributes, it should generally be treated
      as a collection.  If the element contains no recognized child
      elements it should be treated as a non- collection
      WebDAV-compliant resource.

   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:    getlastmodified  supportedlock
   Namespace:  DAV:
   Purpose: Contains the Last-Modified header returned by  To provide a GET method
            without accept headers.
   Value:   HTTP-date  (defined in section 3.3.1 listing of [RFC2616])

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   Protected: SHOULD be protected because some clients may rely on the
            value for appropriate caching behavior, or on the value of lock capabilities supported by
      the Last-Modified header to which this property is linked. resource.
   Protected:  MUST be protected.  Servers determine what lock
      mechanisms are supported, not clients.
   COPY/MOVE behaviour:  This property value is dependent on the last
            modified date kind of
      locks supported at the destination resource, destination, not on the value of the
      property on at the source resource.  Note that some server
            implementations use  Servers attempting to COPY to a
      destination should not attempt to set this property at the file system date modified value for
      destination.
   Description:  The supportedlock property of a resource returns a
      listing of the 'getlastmodified' value, combinations of scope and this is preserved access types which may be
      specified in a
            MOVE even when the HTTP Last-Modified value SHOULD change.
            Thus, clients cannot rely lock request on this value for caching and
            SHOULD use ETags.
   Description: the resource.  Note that the last-modified date on actual
      contents are themselves controlled by access controls so a resource SHOULD
            only reflect changes in the body (the GET responses) of server
      is not required to provide information the
            resource.  A change in a property only client is not
      authorized to see.
   Extensibility:  MAY be extended with any child elements or attributes
      which SHOULD NOT cause be ignored if not recognized.

   <!ELEMENT supportedlock (lockentry)* >

14.10.1  Example - Retrieving the
            last-modified date supportedlock Property
      >>Request

        PROPFIND  /container/ HTTP/1.1
        Host: www.example.com
        Content-Length: xxxx
        Content-Type: text/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: text/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>

15.  Precondition/postcondition XML elements

   The numerical status codes used in HTTP responses are not
   sufficiently granular or informative for all purposes.  Some
   extensions to change, because clients MAY rely on HTTP have used the last-modified date to know when error response body along with some
   status codes in order to overwrite the
            existing body. provide additiona machine-readable response
   detail.  The getlastmodified property MUST be defined
            on any DAV compliant resource that returns machine-readable codes are XML elements classified as
   preconditions (generally client error or failure to meet the Last-
            Modified header
   conditions 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
   Namespace:   DAV:
   Purpose: Describes order for the active locks on a resource
   Protected: MUST request to be protected.  Clients change the list of locks
            through LOCK considered) and UNLOCK, not through PROPPATCH.
   COPY/MOVE behaviour:
   postconditions (generally server error or failure to respond
   successfully to an otherwise valid request).  The value of this property depends on precondition or
   postcondition XML element appears inside an 'error' element which is
   the lock
            state root of the destination, not on the locks XML body of the source
            resource.  Recall that locks are response.  The 'error' root element
   or the precondition or postcondition elements MAY contain additional
   XML elements or attributes not moved defined in a MOVE
            operation.
   Description: The lockdiscovery property returns a listing of who has
            a lock, what type this specification.

   XML elements in error response bodies were not used in RFC2518, but
   were introduced in RFC2518bis.  Thus, use of lock he has, the timeout type and the
            time remaining on these informative
   elements is RECOMMENDED.  Even if clients do not automatically
   recognize the timeout, error bodies they can be quite useful in
   interoperability testing and the associated lock
            token. debugging.

   Name: external-entities-forbidden
   Namespace: DAV:
   Use with: 403 Forbidden
   Purpose: (precondition) -- If there are no locks, but the server supports
            locks, rejects a client request
      because the property will be present but contain zero
            ‘activelock’ elements.  If there is one or more lock, request body contains an
            ‘activelock’ element appears for each lock on external entity, the resource.
   Extensibility: MAY be extended with additional child elements or
            attributes which server
      SHOULD be ignored if not recognized.

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                         WebDAV (RFC2518) bis             October 2003 use this error.

   <!ELEMENT lockdiscovery (activelock)* external-entities-forbidden EMPTY >

14.8.1  Example - Retrieving the lockdiscovery Property

   >>Request

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

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

   >>Response

     HTTP/1.1 207 Multi-Status
     Content-Type: text/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>opaquelocktoken: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>

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          <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 requesturi-must-match-lock-token
   Namespace: DAV:
   Use with: 400 Bad Request
   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.
   COPY/MOVE behaviour: Generally (precondition) -- A request may include a COPY/MOVE of Lock-Token header
      to identify a resource results in lock for the same type purposes of resource at the destination. In a remote
            COPY, the source server SHOULD NOT attempt to set this
            property.
   Description: The resourcetype property MUST be defined on all DAV
            compliant resources.  The default value is empty.
   Extensibility: MAY be extended with any child elements an operation such as
      refresh LOCK or attributes
            which SHOULD be ignored UNLOCK.  However, if the Request-URI doe not recognized.  If fall
      within the element
            contains scope of the 'collection' child element plus additional
            unrecognized elements/attributes, it should generally be
            treated as lock identified by the token, the server
      SHOULD use this error.  The lock may have a collection.  If scope that does not
      include the element contains no
            recognized child elements it should Request-URI, or the lock could have disappeared, or
      the token may be treated as a non-
            collection WebDAV-compliant resource.

   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 invalid.

   <!ELEMENT requesturi-must-match-lock-token EMPTY >

   Name:    supportedlock missing-lock-token
   Namespace: DAV:
   Use with: 400 Bad Request
   Purpose: To provide (precondition) -- If the server rejects a listing of request because
      the request MUST have a lock capabilities supported by token and is missing the resource.
   Protected: MUST be protected. Servers determine what lock mechanisms
            are supported, not clients.

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                         WebDAV (RFC2518) bis             October 2003

   COPY/MOVE behaviour: This property token
      header or header value is dependent (e.g.  on an UNLOCK request), the kind of
            locks supported server
      SHOULD use this error.

   <!ELEMENT missing-lock-token EMPTY >

   Name: live-properties-not-preserved
   Namespace: DAV:
   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, 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 live-properties-not-preserved EMPTY >

   Name: read-only-property
   Namespace: DAV:
   Use with: 403 Forbidden
   Purpose: (precondition) -- The client attempted to set a read-only
      property in a PROPPATCH (such as 'getetag').

   <!ELEMENT read-only-property EMPTY >

   Name: propfind-infinite-depth-forbidden
   Namespace: DAV:
   Use with: 403 Forbidden
   Purpose: (precondition) -- This server does not allow infinite-depth
      PROPFIND requests on collections.

   <!ELEMENT propfind-infinite-depth-forbidden EMPTY >

   Name: need-privileges
   Namespace: DAV:
   Use with: 403 Forbidden
   Purpose: (precondition) -- The currently authenticated user simply
      does not have the value of the
            property at the source resource. Servers attempting to COPY privileges required to do the requested
      operation (e.g.  UNLOCK a destination should lock created by someone else).

   <!ELEMENT need-privileges EMPTY >
   Name: missing-lock-token
   Namespace: DAV:
   Use with: 423 Locked
   Purpose: (precondition) -- The request could not attempt to set this property at succeed because a
      lock token should have been provided.  This element, if present,
      MUST contain the destination.
   Description: The supportedlock property URL of a locked resource returns a
            listing of that prevented the combinations
      request.  In cases of scope MOVE, COPY and access types which
            may DELETE where collection locks
      are involved, it can be specified in a lock request on the resource.  Note
            that difficult for the actual contents are themselves controlled by
            access controls so a server is not required client to provide
            information find out which
      locked resource made the client request fail -- but the server is not authorized to see.
   Extensibility: only
      resonsible for returning one such locked resource.  The server MAY be extended with any child elements or attributes
            which SHOULD be ignored if not recognized.

   <!ELEMENT supportedlock (lockentry)* >

14.10.1 Example - Retrieving
      return every locked resource that prevented the supportedlock Property

   >>Request

     PROPFIND  /container/ HTTP/1.1
     Host: www.example.com
     Content-Length: xxxx
     Content-Type: text/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: text/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>

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              </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>

15 request from
      succeeding if it knows them all.

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

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.

16

17.  DAV Compliance Classes

   A DAV compliant resource can advertise several classes of compliance.
   A client can discover the compliance classes of a

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                         WebDAV (RFC2518) bis             October 2003 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]. RFC2616 [8].

   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.

16.1

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.

16.2

17.2  Class 2

   A class 2 compliant resource MUST meet all class 1 requirements and
   support the LOCK method, the supportedlock property, the
   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.

16.3

17.3  Class "bis" 'bis'

   A resource can explicitly advertise its support for the revisions to
   RFC2518 made in this document.  In particular, this allows clients to
   use the Force-Authentication header on requests.  Class 1 must be
   supported as well.  Class 2 MAY be supported.

   A resource that supports bis MUST support:
    -

   o  the Force-Authentication header.
    -
   o  Any behavior that it supports, in the manner specified in this
      document, rather than in the manner specified in RFC2518, for all
      client requests.  A server MAY use an older behavior for specific
      clients that are discovered to have interoperability problems with
      the requirements of this specification, but MUST NOT use an older
      behavior indiscriminately.

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                         WebDAV (RFC2518) bis             October 2003

   Example:

            DAV: 1, bis

17

18.  Internationalization Considerations

   In the realm of internationalization, this specification complies
   with the IETF Character Set Policy [RFC2277]. RFC2277 [8].  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 [UTF-8] RFC2279 [5] 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 [RFC2376], RFC2376 [17], 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 [REC-XML] XML [11] 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" [RFC2376] RFC2376 [17] 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

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                         WebDAV (RFC2518) bis             October 2003 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
   URI to a user.  We recommend that applications provide human-readable
   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.

18

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]) RFC2616
   [8]) and XML (discussed in [RFC2376]) RFC2376 [17]) 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.

18.1

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

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                         WebDAV (RFC2518) bis             October 2003
   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
   [RFC2069].
   RFC2069 [2].  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.

18.2

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.

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

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

   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.

18.3

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.

18.4

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 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
   lockdiscovery property as appropriate.  Furthermore, user agents
   SHOULD provide control over whether contact information is sent at

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                         WebDAV (RFC2518) bis             October 2003
   all, and if contact information is sent, control over exactly what
   information is sent.

18.5

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
   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.

18.6

19.6  Implications of XML External Entities

   XML supports a facility known as "external entities", defined in
   section 4.2.2 of [REC-XML], XML [11], 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 [REC-XML]. XML [11].  However, [REC-XML] XML
   [11] 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 [RFC2376]. RFC2376 [17].
   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 an error (403 Forbidden, with the
   'forbid-external-entities' element in the error body). precondition defined above
   (external-entities-forbidden).

   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.

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18.7

19.7  Risks Connected with Lock Tokens

   This specification, in section 6.4, requires the use of Universal
   Unique Identifiers (UUIDs) for lock tokens, in order to guarantee
   their uniqueness across space and time.  UUIDs, as defined in [ISO-
   11578],
   ISO-11578 [12], contain a "node" field which "consists of the IEEE
   address, usually the host address.  For systems with multiple IEEE
   802 nodes, any available node address can be used."  Since a WebDAV
   server will issue many locks over its lifetime, the implication is
   that it will also be publicly exposing its IEEE 802 address.

   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.

   Section 24.2 of this specification details an alternate mechanism for
   generating the "node" field of a UUID without using an IEEE 802
   address, which alleviates the risks associated with exposure of IEEE
   802 addresses by using an alternate source of uniqueness.

19

20.  IANA Considerations

   This document defines two namespaces, the namespace of property
   names, and the namespace of WebDAV-specific XML elements used within
   property values.

   The use of XML namespaces means that unique WebDAV property names and
   XML elements can be quickly defined by any WebDAV user or
   application, without requiring IANA action.

   This specification defines a distinguished set of property names and
   XML elements that are understood by all WebDAV applications.  The
   property names and XML elements in this specification are all in the
   "DAV:" namespace.  In natural language, a property like the
   "creationdate" property in the "DAV:" namespace is sometimes
   referred to as "DAV:creationdate" for brevity.

   This specification also defines a URI scheme for the encoding of
   lock tokens, the opaquelocktoken URI scheme described in section
   6.4.

   To ensure correct interoperation based on this specification, IANA
   must reserve the URI namespaces starting with "DAV:" and with

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                         WebDAV (RFC2518) bis             October 2003

   "opaquelocktoken:" for use by this specification, its revisions, and
   related WebDAV specifications.

20 Intellectual Property

   The following notice is copied from RFC 2026 [RFC2026], section
   10.4, and describes the position of the IETF concerning intellectual
   property claims made against this document.

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use other technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights.  Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11.  Copies of
   claims of rights made available for publication and any assurances
   of licenses to be made available, or the result of an attempt made
   "creationdate" property in the "DAV:" namespace is sometimes referred
   to obtain as "DAV:creationdate" for brevity.

   This specification also defines a general license or permission URI scheme for the use of such
   proprietary rights by implementors or users encoding of this specification
   can be obtained from lock
   tokens, the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice opaquelocktoken URI scheme described in section 6.4.

   To ensure correct interoperation based on this standard.  Please address the information to specification, IANA
   must reserve the IETF Executive
   Director.

21 URI namespaces starting with "DAV:" and with
   "opaquelocktoken:" for use by this specification, its revisions, and
   related WebDAV specifications.

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

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                         WebDAV (RFC2518) bis             October 2003 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 RFC2518 bis came from some already named.
   New contributors must also be gratefully acknowledged.  Julian
   Reschke, Geoff Clemm, Joel Soderberg, and Dan Brotsky hashed out
   specific text on the list or in meetings.  Ilya Kirnos supplied text
   for Force-Authentication header.

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                         WebDAV (RFC2518) bis             October 2003

22  Joe Hildebrand contributed as
   co-chair.

22.  References

22.1  Normative References

   [RFC2277] H. T. Alvestrand, "IETF Policy on Character Sets

   [1]   Noble, B., Nguyen, G., Satyanarayanan, M. and
          Languages." R. Katz, "Mobile
         Network Tracing", RFC 2277, BCP 18, 2041, October 1996.

   [2]   Franks, J., Hallam-Baker, P., Hostetler, J., Leach, P.,
         Luotonen, A., Sink, E. and L. Stewart, "An Extension to HTTP :
         Digest Access Authentication", RFC 2069, January 1998.

   [RFC2119] S. 1997.

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

   [RFC2396] T.

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

   [5]   Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
         2279, January 1998.

   [6]   Berners-Lee, R. T., Fielding, R. and L. Masinter, "Uniform
         Resource Identifiers (URI): Generic Syntax." Syntax", RFC 2396, August
         1998.

   [REC-XML] T. Bray, J. Paoli, C. M. Sperberg-McQueen, "Extensible
          Markup Language (XML)." World Wide Web Consortium
          Recommendation REC-xml-20001006.
          http://www.w3.org/TR/2000/REC-xml-20001006, February 1998.

   [REC-XML-NAMES] T. Bray, D. Hollander, A. Layman, "Name Spaces in
          XML" World Wide Web Consortium Recommendation REC-xml-names.
          http://www.w3.org/TR/REC-xml-names-19990114, January 1999.

   [RFC2069] J. Franks, P. Hallam-Baker, J. Hostetler, P. Leach, A.
          Luotonen, E. Sink,

   [7]   Goland, Y., Whitehead, E., Faizi, A., Carter, S. and L. Stewart. "An Extension to HTTP :
          Digest Access Authentication" D. Jensen,
         "HTTP Extensions for Distributed Authoring -- WEBDAV", RFC 2069, January 1997.

   [RFC2616] R.
         2518, February 1999.

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

   [ISO-11578] ISO (International

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

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

   [11]  Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
         "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
         FirstEdition REC-xml-20001006, October 2000.

   [12]  International Organization for Standardization).
          ISO/IEC 11578:1996. Standardization, "Information
         technology - Open Systems Interconnection - Remote Procedure
         Call (RPC)"

   [RFC2141] R. Moats, "URN Syntax." RFC 2141, May 1997.

   [RFC3339] G. Klyne, C. Newman, “Date and Time on the Internet:
          Timestamps.” RFC3339, July 2002.

   [UTF-8] F. Yergeau, "UTF-8, a transformation format of Unicode and (RPC)", ISO 10646." RFC 2279, January 1998.

                           Expires Apr 2004                         91

                         WebDAV (RFC2518) bis             October 2003 Standard 11578, 1996.

22.2  Informational References

   [RFC2026] S.

   [13]  Bradner, S., "The Internet Standards Process - -- Revision 3."
          RFC 2026, 3",
         BCP 9, RFC 2026, October 1996.

   [RFC1807] R.

   [14]  Lasher, R. and D. Cohen, "A Format for Bibliographic Records," Records",
         RFC 1807, June 1995.

   [WF]   C. Lagoze, "The Warwick Framework: A Container Architecture
          for Diverse Sets of Metadata", D-Lib Magazine, July/August
          1996. http://www.dlib.org/dlib/july96/lagoze/07lagoze.html.

   [USMARC] Network Development and MARC Standards, Office, ed. 1994.
          "USMARC Format for Bibliographic Data", 1994. Washington, DC:
          Cataloging Distribution Service, Library of Congress.

   [REC-PICS] J. Miller, T. Krauskopf, P. Resnick, W. Treese, "PICS
          Label Distribution Label Syntax and Communication Protocols"
          Version 1.1, World Wide Web Consortium Recommendation REC-
          PICS-labels-961031. http://www.w3.org/pub/WWW/TR/REC-PICS-
          labels-961031.html.

   [RFC2291] J. A.

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

   [RFC2413] S.

   [16]  Weibel, J. S., Kunze, C. J., Lagoze, C. and M. Wolf, "Dublin Core
         Metadata for Resource Discovery." Discovery", RFC 2413, September 1998.

   [RFC2376] E.

   [17]  Whitehead, E. and M. Murata, Makoto, "XML Media Types." Types", RFC 2376, July
         1998.

   [RFC2396] T. Berners-Lee, R. Fielding, L. Masinter, "Uniform
          Resource Identifiers (URI): Generic Syntax." RFC 2396, August
          1998.

   [RFC3253]  G.

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

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                         WebDAV (RFC2518) bis

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

   [20]  Krauskopf, T., Miller, J., Resnick, P. and W. Treese, "PICS 1.1
         Label Distribution -- Label Syntax and Communication
         Protocols", W3C REC REC-PICS-labels-961031, October 2003

23 1996.

   [21]  Lagoze, C., "The Warwick Framework: A Container Architecture
         for Diverse Sets of Metadata", July/August 1996, <http://
         www.dlib.org/dlib/july96/lagoze/07lagoze.html>.

   [22]  Cataloging Distribution Service, Library of Congress,
         Washington, DC, "Network Development and MARC Standards,
         Office, ed. 1994.  "USMARC Format for Bibliographic Data"",
         1994.

Authors' Addresses

   Lisa Dusseault
   Open Source Application Foundation
   2064 Edgewood Dr.
   Palo Alto, CA  94303
   US

   EMail: lisa@osafoundation.org

   Jason L Crawford
   IBM
   P.O.Box 704
   Yorktown Heights, NY  10598
   US

   EMail: nnjason8451@smallcue.com

Appendix A.  Previous Authors' Addresses

   Editors of RFC2518

   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

   Current Editors

   L. Dusseault
   Xythos Software, Inc.
   25 Maiden Lane, 6th floor
   San Francisco
   Email: lisa@xythos.com

   Jason L Crawford
   P.O.Box 704
   Yorktown Heights, NY 10598
   Phone: 914-784-7569
   Email: nnjason8451@smallcue.com

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24

Appendix B.  Appendices

24.1

B.1  Appendix 1 - Notes on Processing XML Elements

24.1.1

B.1.1  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 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.

B.1.2  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.

B.1.3  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 XML element of allprop.

   Additionally, if a server were lenient and decided to reply to this
   request, the
   form <A></A>.  The second is results would vary randomly from server to declare an XML element of server, with
   some servers executing the form
   <A/>. allprop directive, and others executing
   the propname directive.  This reduces interoperability rather than
   increasing it.

B.1.4  Example - Unknown XML Element

   The previous example was illegal because it contained two XML elements are semantically identical.

24.1.2   Notes on Illegal XML Processing

   XML is a flexible data format that makes it easy to submit data
   that
   appears legal but were explicitly banned from appearing together in fact the propfind
   element.  However, XML is not.  The philosophy an extensible language, so one can imagine
   new elements being defined for use with propfind.  Below is the
   request body of "Be flexible in
   what you accept and strict in what you send" still applies, but it a PROPFIND and, like the previous example, must not be applied inappropriately.  XML is extremely flexible in
   dealing
   rejected with issues of white space, element ordering, inserting new
   elements, etc.  This flexibility a 400 (Bad Request) by a server that does not require extension,
   especially
   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 area of server sees an empty
   propfind, which by the meaning definition of elements.

   There the propfind element is no kindness in accepting illegal combinations of XML
   elements.  At best it will cause an unwanted result and at worst illegal.

   Please note that had the extension been additive it
   can cause real damage.

24.1.3  Example - XML Syntax Error

   The would not
   necessarily have resulted in a 400 (Bad Request).  For example,
   imagine the following request body for a PROPFIND method is illegal. PROPFIND:

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

   The definition of previous example contains the propfind fictitious element only allows for leave-out.  Its
   purpose is to prevent the allprop
   or return of any property whose name matches
   the propname element, not both.  Thus submitted pattern.  If the above is an error and
   must be responded previous example were submitted to with a 400 (Bad Request).

   Imagine, however, that a
   server wanted to be "kind" and decided to
   pick unfamiliar with leave-out, the allprop element as only result would be that the true
   leave-out element would be ignored and respond to it.  A
   client running over a bandwidth limited line who intended to execute a propname would be executed.

B.2  Appendix 2: UUID Node Generation

   UUIDs, as defined in for ISO-11578 [12], contain a big surprise if the server treated "node" field that
   contains one of the
   command as an allprop.

   Additionally, if a server were lenient and decided to reply to this
   request, IEEE 802 addresses for the results would vary randomly from server to server, machine.  As
   noted in section 18, there are several security risks associated with
   some servers executing
   exposing a machine's IEEE 802 address.  This section provides an
   alternate mechanism for generating the allprop directive, and others executing

                           Expires Apr 2004                         94 "node" field of a UUID which
   does not employ an IEEE 802 address.  WebDAV (RFC2518) bis             October 2003 servers MAY use this
   algorithm for creating the propname directive. This reduces interoperability rather than
   increasing it.

24.1.4  Example - Unknown XML Element node field when generating UUIDs.  The previous example was illegal because it contained two elements
   that were explicitly banned from appearing together
   text in the propfind
   element.  However, XML this section is originally from an extensible language, so one can imagine
   new elements being defined for Internet-Draft by Paul
   Leach and Rich Salz, who are noted here to properly attribute their
   work.

   The ideal solution is to obtain a 47 bit cryptographic quality random
   number, and use it as the low 47 bits of the node ID, with propfind.  Below is the
   request body most
   significant bit of a PROPFIND and, like the previous example, must first octet of the node ID set to 1.  This bit
   is the unicast/multicast bit, which will never be set in IEEE 802
   addresses obtained from network cards; hence, there can never be
   rejected with a 400 (Bad Request)
   conflict between UUIDs generated by machines with and without network
   cards.

   If a server that system 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 have a 400 (Bad Request) is returned let us look at primitive to generate cryptographic
   quality random numbers, then in most systems there are usually a
   fairly large number of sources of randomness available from which one
   can be generated.  Such sources are system specific, but often
   include:

   - the
   request body as percent of memory in use - 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 size of main memory in bytes -
   the server does not understand amount of free main memory in bytes - the expired-props element,
   according to size of the WebDAV-specific XML processing rules specified paging or
   swap file in
   section 15, it must ignore it.  Thus the server sees an empty
   propfind, which by bytes - free bytes of paging or swap file - the definition total
   size of user virtual address space in bytes - the propfind element is
   illegal.

   Please note that had total available
   user address space bytes - the extension been additive it would not
   necessarily have resulted size of boot disk drive in a 400 (Bad Request).  For example,
   imagine bytes - 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
   free disk space on boot drive in bytes - the fictitious element leave-out. Its
   purpose is to prevent current time - the return
   amount of any property whose name matches
   the submitted pattern.  If time since the previous example were submitted to a
   server unfamiliar with leave-out, system booted - the only result would be that individual sizes of
   files in various system directories - the
   leave-out element would be ignored creation, last read, and a propname would be executed.

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24.2    Appendix 2: UUID Node Generation

   UUIDs, as defined
   modification times of files in [ISO-11578], contain a "node" field that
   contains one various system directories - the
   utilization factors of various system resources (heap, etc.) -
   current mouse cursor position - current caret position - current
   number of running processes, threads - handles or IDs of the IEEE 802 addresses for desktop
   window and the server machine.  As
   noted in section 18, there are several security risks associated
   with exposing a machine's IEEE 802 address. This section provides an
   alternate mechanism for generating active window - the "node" field value of stack pointer of a UUID which
   does not employ an IEEE 802 address.  WebDAV servers MAY use this
   algorithm for creating the node field when generating UUIDs.  The
   text in this section is originally from an Internet-Draft by Paul
   Leach
   caller - the process and Rich Salz, who are noted here to properly attribute their
   work.

   The ideal solution thread ID of caller - various processor
   architecture specific performance counters (instructions executed,
   cache misses, TLB misses)

   (Note that it is precisely the above kinds of sources of randomness
   that are used to obtain a 47 bit seed cryptographic quality random number, and use it number generators
   on systems without special hardware for their construction.)

   In addition, items such as the low 47 bits of the node ID, with
   the most significant bit of computer's name and the first octet name of the node ID set to 1.
   This bit is the unicast/multicast bit, which will never be set in
   IEEE 802 addresses obtained from network cards; hence, there can
   never be a conflict between UUIDs generated by machines with and
   without network cards.

   If a system does
   operating system, while not have a primitive strictly speaking random, will help
   differentiate the results from those obtained by other systems.

   The exact algorithm to generate cryptographic
   quality random numbers, then in most systems there are usually a
   fairly large number of sources of randomness available from which
   one can be generated. Such sources are node ID using these data is system
   specific, but often
   include:

     - the percent of memory in use
     - because both the size of main memory in bytes
     - data available and the amount of free main memory in bytes
     - functions to obtain
   them are often very system specific.  However, assuming that one can
   concatenate all the size of values from the paging or swap file in bytes
     - free randomness sources into a buffer,
   and that a cryptographic hash function such as MD5 is available, then
   any 6 bytes of paging or swap file
     - the total size of user virtual address space in bytes
     - the total available user address space bytes
     - the size MD5 hash of boot disk drive in bytes
     - the free disk space on boot drive in bytes
     - the current time
     - buffer, with the amount multicast bit
   (the high bit of time since the system booted
     - first byte) set will be an appropriately random
   node ID.

   Other hash functions, such as SHA-1, can also be used.  The only
   requirement is that the individual sizes of files result be suitably random, in various system directories
     - the creation, last read, sense that
   the outputs from a set uniformly distributed inputs are themselves
   uniformly distributed, and modification times of files that a single bit change in
       various system directories
     - the utilization factors input can
   be expected to cause half of various system resources (heap, etc.)
     - current mouse cursor position
     - current caret position
     - current the output bits to change.

B.3  Changes

B.3.1  Changes in -01

B.3.2  Changes in -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 running processes, threads
     - handles or IDs of the desktop window preconditions and postconditions.  The 'missing-lock-token'
   precondition resolves the active window
     - the value REPORT_OTHER_RESOURCE_LOCKED issue.

   Added example of stack pointer matching lock token to URI in the case of a
   collection lock in the caller
     - 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 process and thread ID of caller href element - various processor architecture specific performance counters
       (instructions executed, cache misses, TLB misses)

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   (Note that it is precisely the above kinds of sources of randomness
   that are used generally contains HTTP URIs but
   not always.

   Attempted to seed cryptographic quality random number generators
   on systems without special hardware for their construction.)

   In addition, items such as fix the computer's name and BNF describing the name If header to allow commas
   Clarified presence of Depth header on LOCK refresh requests.

Intellectual Property Statement

   The IETF takes no position regarding the
   operating system, while not strictly speaking random, will help
   differentiate the results from those obtained by validity or scope of any
   intellectual property or other systems.

   The exact algorithm rights that might be claimed to generate a node ID using these data is system
   specific, because both
   pertain to the implementation or use of the data available and technology described in
   this document or the functions extent to
   obtain them are often very system specific. However, assuming which any license under such rights
   might or might not be available; neither does it represent that
   one can concatenate all the values from it
   has made any effort to identify any such rights.  Information on the randomness sources into
   a buffer,
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11.  Copies of
   claims of rights made available for publication and that a cryptographic hash function such as MD5 is
   available, then any 6 bytes assurances of
   licenses to be made available, or the MD5 hash result of an attempt made to
   obtain a general license or permission for the buffer, with the
   multicast bit (the high bit use of the first byte) set will be an
   appropriately random node ID.

   Other hash functions, such as SHA-1,
   proprietary rights by implementors or users of this specification can also be used. The only
   requirement is that the result
   be suitably random _ in the sense
   that the outputs obtained from a set uniformly distributed inputs are
   themselves uniformly distributed, and that a single bit change in the input can IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be expected required to cause half of practice
   this standard.  Please address the output bits information to
   change.

25 the IETF Executive
   Director.

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   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
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   Funding for the RFC Editor function is currently provided by the
   Internet Society.