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Re: [ACTION-33] Trying to sort the SPARQL/Update issues.

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Wed, 27 May 2009 14:16:08 -0400
To: "Steve Harris" <steve.harris@garlik.com>, "Seaborne, Andy" <andy.seaborne@hp.com>
cc: "Kjetil Kjernsmo" <Kjetil.Kjernsmo@computas.com>, "public-rdf-dawg@w3.org" <public-rdf-dawg@w3.org>
Message-ID: <C642FBA8.AC92%ogbujic@ccf.org>
I've been wanting to add my thoughts to this HTTP verb versus SPARQL Update
for some time (but haven't had the chance).

On 5/27/09 12:31 PM, "Steve Harris" <steve.harris@garlik.com> wrote:
>> I don't see the HTTP protocol use as adding operations that can't be
>> done by the language.  They should be aligned.  The language will
>> probably be able to do more.

I don't either, but I think it is important that at the very least, for all
the operations that *can* be supported directly via HTTP there should be an
intuitive HTTP mechanism for it even if there is a mirror of the same
operation in SPARQL update.  The SPARQL update capabilities should 'extend'
(and not replace) what can be done at the HTTP level or it would risk being
at odds with some basic principles of web architecture.

For example, there should be a 'natural' way to simply dispatch a PUT
message (an RDF document) to a SPARQL service and expect that the semantics
of PUT (mostly) dictates what the server should do with the message, rather
than have to 'tunnel' the operation over HTTP via SPARQL Update.  So, from
an RDF dataset perspective, I would interpret:

The PUT method requests that the enclosed entity be stored under the
supplied Request-URI. If the Request-URI refers to an already existing
resource, the enclosed entity SHOULD be considered as a modified version of
the one residing on the origin server. If the Request-URI does not point to
an existing resource, and that URI is capable of being defined as a new
resource by the requesting user agent, the origin server can create the
resource with that URI.

As suggesting that either the RDF graph parsed from the message body 1)
replaces a graph with the name of the request URI or 2) creates a new named
graph with the request URI as the graph name.  A parameter (or HTTP heading)
can override the name of the graph to use, possibly (?graphName=..., etc..)

> I suspect that the PUT/POST/DELETE type tuff is a more natural fit
> into the SPARQL Protocol doc, but no strong feelings on that.

Probably, since the way we interpret PUT/POST/DELETE has more to do with
HTTP than anything else.

-- Chimezie


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Received on Wednesday, 27 May 2009 18:17:00 UTC

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