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Re: Indirect Graph Identification

From: Chime Ogbuji <chimezie@gmail.com>
Date: Fri, 9 Dec 2011 22:06:42 -0500
To: Kjetil Kjernsmo <kjekje@ifi.uio.no>
Cc: public-rdf-dawg-comments@w3.org
Message-ID: <8937AD96C6504A008F67370C73273394@gmail.com>

See comments line. I'm not sure if you intended this as a direct comment to document the document you refer to. In either case, my response is intended to make this thread constructive.
On Friday, December 9, 2011 at 7:42 AM, Kjetil Kjernsmo wrote: 
> In my opinion, what makes this non-RESTful (RESTless?) is that the 
> Request-URI is different from the (embedded) graph URI. 
I'm not sure what you mean by 'non-RESTful' or RESTless. REST is an architectural paradigm that constrains the problem of hypermedia applications in specific ways. Are you saying that a particular constraint is being broken? You should be specific about which one in order to justify why you think downstream applications are negatively impacted by the ability to manipulate < .. insert your favorite name that describes the referent of or what is identified by an RDF graph URI and doesn't offend any particular sensibility ..> that don't have a web presence. Do, you agree that 1) situations like this will arise in practice 2) it is useful to manipulate such "content"? Request for Comments: 3986 allows for this.
> You're manipulating 
> a different resource than you're identifying. 
Query components identify [1] a resource within the scope of the URI's scheme and naming authority. This is not necessarily the same as what is identified by the prefix of the URI up to the query component. Either the naming authority of the embedded / encoded URI is the same as that of this prefix (in which case, this is certainly bad form), it isn't, or it is not available. I would posit that the latter is most likely the reason in most cases where this is needed. The situation before it (where they are different naming authorities) is also quite likely when you consider access control considerations.
> ..snip..
> So, there's a graph http://example.org/foo. We both make a copy of it and 
> stuff it into our public endpoints with the same URI. Then, we use the 
> Graph Store protocol to manipulate these graphs using indirect graph 
> manipulation. Now, there are three different resources with the same URI. 
There is the a) the 'content' of the RDF graph whose URI is ex:foo and the various *distinct* N endpoint manipulation URIs, each which can be used with a web agent and uses the query component as described RFC 3986. 
> ..snip..
> I fear that this will cause very significant problems in the future for 
> SPARQL federation, where agents try to get an idea of what is on different 
> endpoints by exploring service descriptions, etc. They will not be able to 
> rely on that two identical URIs identifying the same graph. Therefore, 
> Request-URI should be the same as graph_uri. 
Are you saying that web agents will not be able to know what to do with URIs? 

[1] http://www.apps.ietf.org/rfc/rfc3986.html#sec-3.4

Chime Ogbuji
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Received on Saturday, 10 December 2011 03:07:15 UTC

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