- From: Jonathan A Rees <rees@mumble.net>
- Date: Sun, 25 Mar 2012 19:01:12 -0400
- To: www-tag@w3.org
Here is an idea to consider among the others. It is partly technical, partly procedural. This does not directly address ISSUE-57 and its implementation does not call for TAG development of the baseline document, so it is not couched as a change proposal. The implementation of this proposal does not have to use these words or be in this form, I am just giving the gist. - The TAG [should it agree to this proposal] recognizes that the referential use of hashless retrieval-enabled http: URIs (what they "identify") is not prescribed by any suitable standard. It is agreed that such a URI can be used to refer to *something*, particularly in RDF, and there is overall consensus on the desire to nurture a global namespace (i.e. have any such URI be used to refer to pretty much the same thing wherever it is used to refer), but there is uncertainty as to how to bring this about. RFC 2616 and HTTPbis do not shed any light on this question as, by design, they do not explain how to determine what an http: URI "identifies" or what constitutes an acceptable "representation" of something. - The TAG recommends a very common extant practice, which is that hashless retrieval-enabled URIs be used to refer to a generic resource whose instances are retrieved using the URI. [See http://www.w3.org/2001/tag/awwsw/ir/latest/ for "instance of".] This allows these URIs to be used in a natural way in RDF, without any "opt in" based on what comes in either the headers or content of protocol responses. The agent(s) providing the representations does not need to know anything about RDF or have to make any statement about what the URI "identifies" in order for a URI to be used in this way. - The TAG recognizes that not everyone follows or will follow this recommendation - some will use these URIs for other purposes. There are many reasons for this, including ignorance, error, and differing engineering judgment. The preceding recommendation should be followed with extreme caution if it appears others might be using the URI in a different way, especially if common use of "opt out" markers emerges. - For the purpose of dispelling uncertainty, i.e. to rule out other interpretations, use of the 'instanceURI' predicate is recommended. This predicate might be used in representations retrieved from the URI, or in other places when anyone wants to clarify that they are using the URI refer to its generic resource. (See http://www.w3.org/2001/tag/awwsw/ir/latest/ for details.) The TAG will take on the responsibility for naming, documenting, and deploying the 'instanceURI' predicate. - [optional] In response to ISSUE-57, the TAG recommends the use of hash URIs in order to avoid performance and difficulty of deployment issues related to the use of 303. Use of hash URIs should also be easier to understand for those new to linked data, based on the "local identifier" narrative, and they avoid problems with URI substitution in the browser address bar. We hope the use of the postfix "#it" or "#_" or "#" pattern for indirection will be promoted when it is called for, perhaps as an additional option in some future revision of "Cool URIs for the Semantic Web". - The TAG recognizes that the semantic web / linked data community is the proper place for continuing consideration of this set of issues as they pertain to URI occurrences in RDF documents. If consideration of solutions to ISSUE-57 other than the one given above is a community priority, this should be taken up in a forum such as an RDF-related working group or a W3C community group, that involves those who have a stake in the matter. - The above, together with the work of the HTTP WG on 303 responses to GET requests, supersedes the advice given in http://lists.w3.org/Archives/Public/www-tag/2005Jun/0039.html .
Received on Sunday, 25 March 2012 23:01:41 UTC