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Versions: 00 01 02 03 04 05 06 RFC 5689

Network Working Group                                           C. Daboo
Internet-Draft                                                Apple Inc.
Intended status: Standards Track                       November 28, 2008
Expires: June 1, 2009


                       Extended MKCOL for WebDAV
                  draft-ietf-vcarddav-webdav-mkcol-02

Status of This Memo

   By submitting this Internet-Draft, each author represents that any
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   This Internet-Draft will expire on June 1, 2009.

Abstract

   This specification extends the Web Distributed Authoring and
   Versioning (WebDAV) MKCOL method to allow collections of arbitrary
   resourcetype to be created and to allow properties to be set at the
   same time.











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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  WebDAV extended MKCOL  . . . . . . . . . . . . . . . . . . . .  3
     3.1.  Extended MKCOL Support . . . . . . . . . . . . . . . . . .  4
       3.1.1.  Example: Using OPTIONS for the Discovery of
               Support for Extended MKCOL . . . . . . . . . . . . . .  4
     3.2.  Status Codes . . . . . . . . . . . . . . . . . . . . . . .  5
     3.3.  Additional Precondition for Extended MKCOL . . . . . . . .  5
     3.4.  Example: Successful Extended MKCOL Request . . . . . . . .  5
   4.  Replacing Existing MKxxx Methods . . . . . . . . . . . . . . .  6
     4.1.  MKCALENDAR Replacement . . . . . . . . . . . . . . . . . .  7
       4.1.1.  Example: Replacing MKCALENDAR with MKCOL . . . . . . .  7
   5.  XML Element Definitions  . . . . . . . . . . . . . . . . . . .  9
     5.1.  mkcol XML Element  . . . . . . . . . . . . . . . . . . . .  9
     5.2.  mkcol-response XML Element . . . . . . . . . . . . . . . .  9
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 10
   9.  Normative References . . . . . . . . . . . . . . . . . . . . . 10
   Appendix A.  Change History (to be removed prior to
                publication as an RFC)  . . . . . . . . . . . . . . . 11




























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1.  Introduction

   WebDAV [RFC4918] defines the HTTP [RFC2616] method MKCOL.  This
   method is used to create WebDAV collections on the server.  However,
   several WebDAV-based specifications (e.g., CalDAV [RFC4791]) define
   "special" collections - ones which are identified by additional
   values in the DAV:resourcetype property assigned to the collection
   resource, or through other means.  These "special" collections are
   created by new methods (e.g., MKCALENDAR).  The addition of a new
   MKxxx method for each new "special" collection adds to server
   complexity and is detrimental to overall reliability due to the need
   to make sure intermediaries are aware of these methods.

   This specification proposes an extension to the WebDAV MKCOL method
   that adds a request body allowing a client to specify WebDAV
   properties to be set on the newly created collection or resource.  In
   particular, the DAV:resourcetype property can be used to create a
   "special" collection, or other properties used to create a "special"
   resource.  This avoids the need to invent new MKxxx methods.

2.  Conventions Used in This Document

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

   Definitions of XML elements in this document use XML element type
   declarations (as found in XML Document Type Declarations), described
   in Section 3.2 of [W3C.REC-xml-20060816].

   When XML element types in the namespace "DAV:" are referenced in this
   document outside of the context of an XML fragment, the string "DAV:"
   will be prefixed to the element type names.

   Processing of XML by clients and servers MUST follow the rules
   described in Appendix A of [RFC4918].

3.  WebDAV extended MKCOL

   The WebDAV MKCOL request is extended to allow the inclusion of a
   request body.  The request body is an XML document containing a
   single DAV:mkcol XML element as the root element.  The Content-Type
   request header MUST be set appropriately for an XML body (e.g., set
   to "text/xml" or "application/xml").  XML-typed bodies for an MKCOL
   request that do not have DAV:mkcol as the root element are reserved
   for future usage.

   One or more DAV:set XML elements MAY be included in the DAV:mkcol XML



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   element to allow setting properties on the collection as it is
   created.  In particular, to create a collection of a particular type,
   the DAV:resourcetype XML element MUST be included in a DAV:set XML
   element and MUST specify the expected resource type elements for the
   new resource, that MUST include the DAV:collection element that needs
   to be present for any WebDAV collection.

   As per the PROPPATCH method ([RFC4918], Section 9.2), servers MUST
   process any DAV:set instructions 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.  Failure to set a property value on the
   collection MUST result in a failure of the overall MKCOL request.

   If a server attempts to make any of the property changes in an
   extended MKCOL request (i.e., the request is not rejected for high-
   level errors before processing the body), the response MUST be an XML
   document containing a single DAV:mkcol-response XML element, which
   MUST contain DAV:propstat XML elements with the status of each
   property.

   In all other respects the behavior of the extended MKCOL request
   follows that of the standard MKCOL request.

3.1.  Extended MKCOL Support

   A server supporting the features described in this document, MUST
   include "extended-mkcol" as a field in the DAV response header from
   an OPTIONS request on any URI that supports use of the extended MKCOL
   method.

3.1.1.  Example: Using OPTIONS for the Discovery of Support for Extended
        MKCOL

   >> Request <<

   OPTIONS /addressbooks/users/ HTTP/1.1
   Host: addressbook.example.com












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   >> Response <<

   HTTP/1.1 200 OK
   Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
   Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, REPORT, ACL
   DAV: 1, 2, 3, access-control, extended-mkcol
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Length: 0

3.2.  Status Codes

   As per Section 9.3.1 of [RFC4918].

3.3.  Additional Precondition for Extended MKCOL

   WebDAV ([RFC4918], Section 16) defines preconditions and
   postconditions for request behavior.  This specification adds the
   following precondition for the extended MKCOL request.

   Name:  valid-resourcetype

   Namespace:  DAV:

   Use with:  Typically 403 (Forbidden)

   Purpose:  (precondition) -- The server MUST support the specified
      resourcetype value for the specified collection.

3.4.  Example: Successful Extended MKCOL Request

   This example shows how the extended MKCOL request is used to create a
   collection of a fictitious type "special-resource".



















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   >> Request <<

   MKCOL /home/special/ HTTP/1.1
   Host: special.example.com
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:mkcol xmlns:D="DAV:"
                 xmlns:E="http://example.com/ns/">
     <D:set>
       <D:prop>
         <D:resourcetype>
           <D:collection/>
           <E:special-resource/>
         </D:resourcetype>
         <D:displayname>Special Resource</D:displayname>
       </D:prop>
     </D:set>
   </D:mkcol>

   >> Response <<

   HTTP/1.1 201 Created
   Cache-Control: no-cache
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:mkcol-response xmlns:D="DAV:">
     <D:propstat>
       <D:prop>
         <D:resourcetype/>
         <D:displayname/>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:mkcol-response>

4.  Replacing Existing MKxxx Methods

   One of the goals of this extension is to eliminate the need for other
   extensions to define their own variant of MKCOL to create the special
   collections they need.  This extension can be used to replace
   existing MKxxx methods in other extensions as detailed below.  If a
   server supports this extension and the other extension listed, then
   the server MUST support use of the extended MKCOL method to achieve



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   the same result as the MKxxx method of the other extension.

4.1.  MKCALENDAR Replacement

   CalDAV defines the MKCALENDAR method to create a calendar collection
   as well as set properties during creation ([RFC4791], Section 5.3.1).

   The extended MKCOL method can be used instead by specifying both DAV:
   collection and CALDAV:calendar-collection XML elements in the DAV:
   resourcetype property, set during the extended MKCOL request.

4.1.1.  Example: Replacing MKCALENDAR with MKCOL

   The first example below shows an MKCALENDAR request containing a
   CALDAV:mkcalendar XML element in the request body, and returning a
   CALDAV:mkcalendar-response XML element in the response body.  The
   second example shows the equivalent extended MKCOL request with the
   same request and response XML elements.

   >> MKCALENDAR Request <<

   MKCALENDAR /home/lisa/calendars/events/ HTTP/1.1
   Host: calendar.example.com
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <C:mkcalendar xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:caldav">
     <D:set>
       <D:prop>
         <D:displayname>Lisa's Events</D:displayname>
       </D:prop>
     </D:set>
   </C:mkcalendar>
















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   >> MKCALENDAR Response <<

   HTTP/1.1 201 Created
   Cache-Control: no-cache
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <C:mkcalendar-response xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:caldav">
     <D:propstat>
       <D:prop>
         <D:displayname/>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </C:mkcalendar-response>

   >> MKCOL Request <<

   MKCOL /home/cyrus/calendars/events/ HTTP/1.1
   Host: calendar.example.com
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:mkcol xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:caldav">
     <D:set>
       <D:prop>
         <D:resourcetype>
           <D:collection/>
           <C:calendar/>
         </D:resourcetype>
         <D:displayname>Cyrus' Events</D:displayname>
       </D:prop>
     </D:set>
   </D:mkcol>












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   >> MKCOL Response <<

   HTTP/1.1 201 Created
   Cache-Control: no-cache
   Date: Sat, 11 Nov 2006 09:32:12 GMT
   Content-Type: application/xml; charset="utf-8"
   Content-Length: xxxx

   <?xml version="1.0" encoding="utf-8" ?>
   <D:mkcol-response xmlns:D="DAV:"
                 xmlns:C="urn:ietf:params:xml:ns:caldav">
     <D:propstat>
       <D:prop>
         <D:resourcetype/>
         <D:displayname/>
       </D:prop>
       <D:status>HTTP/1.1 200 OK</D:status>
     </D:propstat>
   </D:mkcol-response>

5.  XML Element Definitions

5.1.  mkcol XML Element

   Name:  mkcol

   Namespace:  DAV:

   Purpose:  Used in a request to specify properties to be set in an
      extended MKCOL request, as well as any additional information
      needed when creating the resource.

   Description:  This XML element is a container for the information
      required to modify the properties on a collection resource as it
      is created in an extended MKCOL request.

   Definition:

       <!ELEMENT mkcol (set+)>

5.2.  mkcol-response XML Element

   Name:  mkcol-response

   Namespace:  DAV:






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   Purpose:  Used in a response to indicate the status of properties
      that were set or failed to be set during an extended MKCOL
      request.

   Description:  This XML element is a container for the information
      returned about a resource that has been created in an extended
      MKCOL request.

   Definition:

       <!ELEMENT mkcol-response (propstat+, ANY)>

6.  Security Considerations

   This extension does not introduce any new security concerns beyond
   those already described in HTTP and WebDAV.

7.  IANA Considerations

   This document does not require any actions on the part of IANA.

8.  Acknowledgments

   Several people suggested this approach, including Julian Reschke and
   Bernard Desruisseaux.  Thanks also to Mike Douglass.

9.  Normative References

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

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

   [RFC4791]               Daboo, C., Desruisseaux, B., and L.
                           Dusseault, "Calendaring Extensions to WebDAV
                           (CalDAV)", RFC 4791, March 2007.

   [RFC4918]               Dusseault, L., "HTTP Extensions for Web
                           Distributed Authoring and Versioning
                           (WebDAV)", RFC 4918, June 2007.

   [W3C.REC-xml-20060816]  Paoli, J., Yergeau, F., Bray, T., Sperberg-
                           McQueen, C., and E. Maler, "Extensible Markup
                           Language (XML) 1.0 (Fourth Edition)", World



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                           Wide Web Consortium Recommendation REC-xml-
                           20060816, August 2006,
                           <http://www.w3.org/TR/2006/REC-xml-20060816>.

Appendix A.  Change History (to be removed prior to publication as an
             RFC)

   Changes from -01:

   1.  Minor formatting/wording changes proposed by Julian Reschke were
       applied.

   2.  Removed reference to DeltaV entirely as the spec no longer
       replaces the MKxxx DeltaV defines.

   3.  Added Namespace definition to precondition.

   4.  Added reference to 4918 XML extensibility rules.

   5.  Added statement that DAV:collection must be present in DAV:
       resourcetype in the request.

   6.  Added statement on use of DTD fragments.

   7.  Added statement about setting proper Content-Type for the MKCOL
       body.

   8.  Added statement that MKCOL bodies using a different root element
       are reserved for future extensions.

   Changes from -00:

   1.  Fixed an example.

   Changes from draft-daboo-webdav-mkcol-00:

   1.  Removed MKACTIVITY and MKWORKSPACE replacement behavior.

   2.  Added valid-resourcetype precondition.












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Author's Address

   Cyrus Daboo
   Apple Inc.
   1 Infinite Loop
   Cupertino, CA  95014
   USA

   EMail: cyrus@daboo.name
   URI:   http://www.apple.com/









































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