Network Working Group C. Daboo
Internet-Draft Apple Inc.
Intended status: Standards Track May 14, 2008
Expires: November 15, 2008
Extended MKCOL for WebDAV
draft-ietf-vcarddav-webdav-mkcol-00
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Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract
This specification extends the 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 . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Additional Precondition for extended MKCOL . . . . . . . . 4
3.4. Example: Successful extended MKCOL Request . . . . . . . . 5
4. Replacing existing MKxxx methods . . . . . . . . . . . . . . . 6
4.1. MKCALENDAR replacement . . . . . . . . . . . . . . . . . . 6
4.1.1. Example: Replacing MKCALENDAR with MKCOL . . . . . . . 6
5. XML Element Definitions . . . . . . . . . . . . . . . . . . . 8
5.1. mkcol XML Element . . . . . . . . . . . . . . . . . . . . 8
5.2. mkcol-response XML Element . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
9. Normative References . . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Change History (to be removed prior to
publication as an RFC) . . . . . . . . . . . . . . . 10
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1. Introduction
WebDAV [RFC4918] defines an HTTP [RFC2616] method MKCOL. This method
is used to create WebDAV collections on the server. However, several
WebDAV-based specifications (e.g., DeltaV [RFC3253], CalDAV
[RFC4791]) define "special" collections or resources - 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., MKACTIVITY,
MKWORKSPACE, MKCALENDAR). The addition of a new MKxxx method for
each new "special" collection or resource 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].
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.
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 at the top-level. 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 correct resource type elements for the new
resource.
As per the PROPPATCH method, 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
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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 resource 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.
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Name: valid-resourcetype
Use with: Typically 403 Forbidden
Purpose: (precondition) -- The server does not support the specified
resourcetype value for any collections.
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".
>> Request <<
MKCOL /home/special/ HTTP/1.1
Host: special.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Special Resource
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>> 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
HTTP/1.1 200 OK
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
the same result as the MKxxx method of the other extension.
4.1. MKCALENDAR replacement
CalDAV [RFC4791] defines the MKCALENDAR method to create a calendar
collection as well as set properties during creation.
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.
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>> MKCALENDAR Request <<
MKCALENDAR /home/lisa/calendars/events/ HTTP/1.1
Host: calendar.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Lisa's Events
>> 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
HTTP/1.1 200 OK
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>> MKCOL Request <<
MKCOL /home/cyrus/calendars/events/ HTTP/1.1
Host: calendar.example.com
Content-Type: application/xml; charset="utf-8"
Content-Length: xxxx
Cyrus' Events
>> 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
HTTP/1.1 200 OK
5. XML Element Definitions
5.1. mkcol XML Element
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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:
5.2. mkcol-response XML Element
Name: mkcol-response
Namespace: DAV:
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:
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.
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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.
[RFC3253] Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J.
Whitehead, "Versioning Extensions to WebDAV
(Web Distributed Authoring and Versioning)", RFC 3253,
March 2002.
[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.
Appendix A. Change History (to be removed prior to publication as an
RFC)
Changes from draft-daboo-webdav-mkcol-00:
1. Removed MKACTIVITY and MKWORKSPACE replacement behavior.
2. Added valid-resourcetype precondition.
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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