- From: John Bradley <john.bradley@wingaa.com>
- Date: Fri, 12 Sep 2008 09:27:37 -0700
- To: "Booth, David (HP Software - Boston)" <dbooth@hp.com>
- Cc: "elharo@metalab.unc.edu" <elharo@metalab.unc.edu>, "www-tag@w3.org" <www-tag@w3.org>
- Message-Id: <0014881A-C24D-4C49-BC89-ACE34B0596AF@wingaa.com>
Hi David, thing-described-by.org is a good example of the use of 303 redirects. In HXRI and XRDS-Simple we do want "aware" applications to be able directly request the meta data about the "thing" that the URI is about. XRDS-Simole as used in openID, oAuth, OpenSocial and other places, currently use the accept header to request the XRDS meta-data as opposed to HTML content. For example https://ve7jtb.pip.verisignlabs.com/ with no accept header returns my personal identity page. The same URL with an accept header specifying MIME media type, application/xrds+xml, returns XRDS meta-data. For the HXRI proxy the request for the XRDS meta-data is accomplished by appending a query string to the URI. One of the things we are looking for is the best way to indicate in a query about a "thing" that you want a particular sort of meta-data about the "thing", XRDS document, RDF document, or something else. When the URI is about a "thing" in meet space what is the meaning of content negotiation? One of the things that we need the most work on is how to perform what might be thought of meta-data content negotiation for URI that are about "things". The best solution we have found at this point is to use Link Headers to indicate where the related meta-data can be found at distinct URI. This is would be consistent with Mark Nottingham's draft recommendations: http://www.mnot.net/drafts/draft-nottingham-http-link-header-01.txt This clearly requires an extra GET that some users are resistant to. Perhaps that is just a limitation of http: that we will have to live with. The XRDS-Simple community has raised the possibility of using OPTIONS and custom request headers as ways of doing meta-data content negotiation. The XRI-TC is looking for input on this. Our desire is that revisions to HXRI and XRDS-Simple are as compatible with AWWW as possible. I know that people like David Booth have been thinking about this for some time. Thanks John Bradley On 12-Sep-08, at 7:15 AM, Booth, David (HP Software - Boston) wrote: >> From: John Bradley [mailto:john.bradley@wingaa.com] >> [ . . . ] >> The XRI TC originally selected the 302 redirect for >> compatibility with pre http 1.1 browsers. >> Changing to 303 redirects may brake some clients but it >> unlikely to be a significant issue. >> >> I understand that some people will feel that using redirects >> is inefficient, however it seems the only way to communicate >> the desired qualities of the identifier in http: > > Yes, there would be an extra round trip for an agent that is not > aware of the XRI http subscheme conventions. But an agent that *is* > aware of the conventions could inspect the URI and safely skip the > extra round trip, in a manner similar to the optimization suggested > for thing-described-by.org: > http://thing-described-by.org/#optimizing > That seems like a reasonable trade-off to me: naive agents incur a > small penalty, but agents doing high volume have the option to > safely optimize. > > > David Booth, Ph.D. > HP Software > +1 617 629 8881 office | dbooth@hp.com > http://www.hp.com/go/software > > Statements made herein represent the views of the author and do not > necessarily represent the official views of HP unless explicitly so > stated. >
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Received on Friday, 12 September 2008 16:41:57 UTC