|Network Working Group||A. Brown|
|Intended status: Informational||IBM|
|Expires: July 16, 2010||J. Reschke, Editor|
|January 12, 2010|
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/>).
Note that although discussion takes place on the Atompub working group's mailing list, this is not a working group document.
XML versions, latest edits and the issues list for this document are available from <http://greenbytes.de/tech/webdav/#draft-brown-versioning-link-relations>.
This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on July 16, 2010.
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|I edit (type: edit, status: closed)|
|firstname.lastname@example.org||2009-11-19||Umbrella issue for editorial fixes/enhancements.|
|Associated changes in this document: A.1, B.|
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.
|I expose-urls (type: change, status: closed)|
In general this mechanism seems sound but I'm not sure that
the security considerations are entirely adequate. This
mechanism lets you learn information about other versions
of a resource even if you potentially don't have permission
to view them directly. Consider a limiting case where each
version of the resource had a name that contained the
change set for that resource. E.g.,
In this case, seeing other parts of the version tree leaks information about those versions. I don't think that this is a problem for the draft, but it might be useful to mention that this feature has implications for name construction.
|2010-01-06||Resolution:Add that consideration.|
|Associated changes in this document: 5.|
Automated agents should take care when these relations cross administrative domains (e.g., the URI has a different authority than the current document). Such agents should also take care to detect circular references.
Thanks to the members of Content Management Interoperability Services (CMIS) Technical Committee (TC) at OASIS for the initial proposal, and to Jan Algermissen for feedback during IETF review.
|[RFC4287]||Nottingham, M. and R. Sayre, “The Atom Syndication Format”, RFC 4287, December 2005.|
|[CMIS]||Brown, A., Gur-Esh, E., McVeigh, R., and F. Muller, “Content Management Interoperability Services (CMIS) Version 1.0”, OASIS CMIS v1.0 Committee Draft 04, September 2009, <http://docs.oasis-open.org/cmis/CMIS/v1.0/cd04/cmis-spec-v1.0.html>.|
|[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(tm) 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.|
|[RFC5023]||Gregorio, J. and B. de hOra, “The Atom Publishing Protocol”, RFC 5023, October 2007.|
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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]).
VERSION-CONTROL /docs/test.txt HTTP/1.1 Host: example.net
200 OKLink: </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
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.
Add and resolve issue "iana".
Fix typo ("working-resource" instead of "working-copy"). Add and resolve issues "checked-out", "cmis" and "working-copy-of".
Close issue "working-copy-of", which was really fixed in -04.