|Network Working Group||A. Brown|
|Intended status: Informational||IBM|
|Expires: May 23, 2010||J. Reschke, Editor|
|November 19, 2009|
Link Relations for Simple Version Navigation
Note: a later version of this document has been published as RFC5829.
This specification defines Atom link relations for navigation between a resource and its versions.
Please send comments to the Atom Syntax mailing list (<http://www.imc.org/atom-syntax/>).
This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.
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This specification defines link relations that may be used on a resource that exists in a system that supports versioning to navigate among the different resources available, such as past versions.
The following link relations are defined:
Automated agents should take care when these relation crosses administrative domains (e.g., the URI has a different authority than the current document).
The link relations defined in Section 3 are to be registered by IANA per [RFC4287]. [lhdraft: Will be updated to follow [draft-nottingham-http-link-header] once approved by the IESG. --jre]
All link relations defined in this document will have the following expected display characteristics:
|[RFC4287]||Nottingham, M. and R. Sayre, “The Atom Syndication Format”, RFC 4287, December 2005.|
|[draft-nottingham-http-link-header]||Nottingham, M., “Web Linking”, Internet-Draft draft-nottingham-http-link-header-06 (work in progress), July 2009.|
|[JSR-283]||Day Software, Nuescheler, D., and P. Piegaze, “Content Repository API for Java™ Technology Specification”, Java Specification Request 283, August 2009, <http://www.day.com/specs/jcr/2.0/>.|
|[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.|
The link relations defined in Section 3 correspond to various properties used in WebDAV Versioning [RFC3253] and JCR [JSR-283]:
The "Web Linking" specification ([draft-nottingham-http-link-header]) generalizes Atom link relations, and also re-introduces the HTTP "Link" header as a way to expose link relations in HTTP responses. This will make it possible to expose version links independently from a specific vocabulary, be it the Atom Feed Format ([RFC4287]) or WebDAV properties ([RFC3253]).
For instance, a response to an VERSION-CONTROL request ([RFC3253], Section 3.5) could expose newly created version-history and checked-in version as link relations:
VERSION-CONTROL /docs/test.txt HTTP/1.1 Host: example.net
HTTP/1.1 200 OK Link: </system/v/84345634/1>; rel=latest-version; anchor=</docs/test.txt> Link: </system/vh/84345634>; rel=version-history; anchor=</docs/test.txt>
(Note that in this case, the anchor parameter is used, as the response to a VERSION-CONTROL request is not a representation of the resource at the Request-URI)
A subsequent HEAD request on that resource could expose the version-history and latest-version relations as well:
HEAD /docs/test.txt HTTP/1.1 Host: example.net
HTTP/1.1 200 OK Content-Type: text/plain; charset=UTF-8 Content-Length: 12345 Link: </system/v/84345634/1>; rel=latest-version Link: </system/vh/84345634>; rel=version-history
After creating more versions, following the latest-version would then expose predecessors of a version:
HEAD /system/v/84345634/3 HTTP/1.1 Host: example.net
HTTP/1.1 200 OK Content-Type: text/plain; charset=UTF-8 Content-Length: 12323 Link: </system/v/84345634/2>; rel=predecessor-version
The content and concepts within are a product of the Content Management Interoperability Services (CMIS) Technical Committee (TC) at OASIS.
All members of the TC have contributed.
Added Geoff Clemm as author.
Renamed link relation "all-versions" to "version-history". Fixed description of "working-resource" relation to state that it appears on a version resource.
Rewrite terminology and link relations using simpler definitions that can reflect versioning approaches different from WebDAV.
Add JCR/WebDAV property table. And reference to Web Linking draft (for now informative) and examples showing use of the Link header.