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rfc:rfc5689

Network Working Group C. Daboo Request for Comments: 5689 Apple Inc. Updates: 4791, 4918 September 2009 Category: Standards Track

Extended MKCOL for Web Distributed Authoring and Versioning (WebDAV)

Abstract

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

Status of This Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (c) 2009 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may

Daboo Standards Track [Page 1] RFC 5689 Extended MKCOL for WebDAV September 2009

 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Table of Contents

 1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
 2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
 3.  WebDAV Extended MKCOL  . . . . . . . . . . . . . . . . . . . .  4
   3.1.  Extended MKCOL Support . . . . . . . . . . . . . . . . . .  5
     3.1.1.  Example: Using OPTIONS for the Discovery of
             Support for Extended MKCOL . . . . . . . . . . . . . .  5
   3.2.  Status Codes . . . . . . . . . . . . . . . . . . . . . . .  5
   3.3.  Additional Precondition for Extended MKCOL . . . . . . . .  5
   3.4.  Example: Successful Extended MKCOL Request . . . . . . . .  6
   3.5.  Example: Unsuccessful Extended MKCOL Request . . . . . . .  6
 4.  Using Extended MKCOL as an Alternative for MKxxx Methods . . .  8
   4.1.  MKCALENDAR Alternative . . . . . . . . . . . . . . . . . .  8
     4.1.1.  Example: Using MKCOL Instead of MKCALENDAR . . . . . .  8
 5.  XML Element Definitions  . . . . . . . . . . . . . . . . . . . 10
   5.1.  mkcol XML Element  . . . . . . . . . . . . . . . . . . . . 10
   5.2.  mkcol-response XML Element . . . . . . . . . . . . . . . . 10
 6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
 7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 11
 8.  Normative References . . . . . . . . . . . . . . . . . . . . . 11

Daboo Standards Track [Page 2] RFC 5689 Extended MKCOL for WebDAV September 2009

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 that are identified by additional
 values in the DAV:resourcetype property assigned to the collection
 resource or by 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 defines 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; alternatively, other properties can be 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].
 This document uses XML DTD fragments (Section 3.2 of
 [W3C.REC-xml-20081126]) as a purely notational convention.  WebDAV
 request and response bodies cannot be validated by a DTD due to the
 specific extensibility rules defined in Section 17 of [RFC4918] and
 due to the fact that all XML elements defined by this specification
 use the XML namespace name "DAV:".  In particular:
 1.  Element names use the "DAV:" namespace.
 2.  Element ordering is irrelevant unless explicitly stated.
 3.  Extension elements (elements not already defined as valid child
     elements) may be added anywhere, except when explicitly stated
     otherwise.
 4.  Extension attributes (attributes not already defined as valid for
     this element) may be added anywhere, except when explicitly
     stated otherwise.

Daboo Standards Track [Page 3] RFC 5689 Extended MKCOL for WebDAV September 2009

 When an XML element type in the "DAV:" namespace is referenced in
 this document outside of the context of an XML fragment, the string
 "DAV:" will be prefixed to the element type.
 This document inherits, and sometimes extends, DTD productions from
 Section 14 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
 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, which MUST include the DAV:collection element that
 needs to be present for any WebDAV collection.
 As per the PROPPATCH method (Section 9.2 of [RFC4918]), servers MUST
 process any DAV:set instructions in document order (an exception to
 the normal rule that ordering is irrelevant).  If any one instruction
 fails to execute successfully, all instructions MUST fail (i.e.,
 either all succeed or all fail).  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 --
 i.e., the collection is not created.
 The response to an extended MKCOL request 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
 when the request fails due to a failure to set one or more of the
 properties specified in the request body.  The server MAY return a
 response body in the case where the request is successful, indicating
 success for setting each property specified in the request body.
 When an empty response body is returned with a success request status
 code, the client can assume that all properties were set.
 In all other respects, the behavior of the extended MKCOL request
 follows that of the standard MKCOL request.

Daboo Standards Track [Page 4] RFC 5689 Extended MKCOL for WebDAV September 2009

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
 >> 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.

Daboo Standards Track [Page 5] RFC 5689 Extended MKCOL for WebDAV September 2009

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".  The response
 body is empty as the request completed successfully.
 >> 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

3.5. Example: Unsuccessful Extended MKCOL Request

 This example shows an attempt to use the extended MKCOL request to
 create a collection of a fictitious type "special-resource", which is
 not actually supported by the server.  The response body shows that
 an error occurred specifically with the DAV:resourcetype property.

Daboo Standards Track [Page 6] RFC 5689 Extended MKCOL for WebDAV September 2009

 >> 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/1.1 403 Forbidden
 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:prop>
     <D:status>HTTP/1.1 403 Forbidden</D:status>
     <D:error><D:valid-resourcetype /></D:error>
     <D:responsedescription>Resource type is not
     supported by this server</D:responsedescription>
   </D:propstat>
   <D:propstat>
     <D:prop>
       <D:displayname/>
     </D:prop>
     <D:status>HTTP/1.1 424 Failed Dependency</D:status>
   </D:propstat>
 </D:mkcol-response>

Daboo Standards Track [Page 7] RFC 5689 Extended MKCOL for WebDAV September 2009

4. Using Extended MKCOL as an Alternative for 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 as an alternative
 to 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
 the same result as the MKxxx method of the other extension.

4.1. MKCALENDAR Alternative

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

 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.
 >> 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>

Daboo Standards Track [Page 8] RFC 5689 Extended MKCOL for WebDAV September 2009

 >> 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>
 The second example shows the equivalent extended MKCOL request with
 the same request and response XML elements.
 >> MKCOL Request <<
 MKCOL /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" ?>
 <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>Lisa's Events</D:displayname>
     </D:prop>
   </D:set>
 </D:mkcol>

Daboo Standards Track [Page 9] RFC 5689 Extended MKCOL for WebDAV September 2009

 >> 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:

Daboo Standards Track [Page 10] RFC 5689 Extended MKCOL for WebDAV September 2009

 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+)>

6. Security Considerations

 This extension does not introduce any new security concerns beyond
 those already described in HTTP [RFC2616] and WebDAV [RFC4918].

7. Acknowledgments

 Thanks to Bernard Desruisseaux, Mike Douglass, Alexey Melnikov,
 Julian Reschke, and Simon Vaillancourt.

8. 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-20081126]
            Maler, E., Yergeau, F., Paoli, J., Bray, T., and C.
            Sperberg-McQueen, "Extensible Markup Language (XML) 1.0
            (Fifth Edition)", World Wide Web Consortium
            Recommendation REC-xml-20081126, November 2008,
            <http://www.w3.org/TR/2008/REC-xml-20081126>.

Daboo Standards Track [Page 11] RFC 5689 Extended MKCOL for WebDAV September 2009

Author's Address

 Cyrus Daboo
 Apple Inc.
 1 Infinite Loop
 Cupertino, CA  95014
 USA
 EMail: cyrus@daboo.name
 URI:   http://www.apple.com/

Daboo Standards Track [Page 12]

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