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Indicating query type

From: Danny Ayers <danny.ayers@gmail.com>
Date: Sat, 27 May 2006 11:09:31 +0200
Message-ID: <1f2ed5cd0605270209u6dacc05exb73fcaf0605581b3@mail.gmail.com>
To: public-sparql-dev@w3.org

Hi folks,

I've been mulling over using SPARQL alongside RDF serializations as an
agent communication language (a la old-AI), with the underlying
protocol naturally being HTTP. An agent will basically be a
triplestore attached to a HTTP client and server with whatever
additional processing may be required. A TELL kind of message will be
a graph, an ASK a SPARQL query. As both RDF/XML and SPARQL have there
own mime types there's a natural fit to HTTP at this level.

But a puzzle I've got is how best to indicate up front whether the
query is a SELECT, CONSTRUCT, ASK or DESCRIBE. At least I'm assuming
this is the right way to go - the different query types are quite
different, from the agent viewpoint presumably they'd correspond to
different performatives, from the HTTP point of view they're only a
teeny bit below GET, PUT etc. So I reckon it would make sense to lift
the query type out of the content somehow (and it should be helpful to
be able to dispatch at HTTPrequest time, prior to parsing).

Right now I'm thinking maybe using a HTTP header. Pragma: looks fairly
close, but I'm very much open to suggestions. Whatever is used, I
reckon it's important for the client/server to behave transparently as
a regular client/server (e.g. an Atom Store Agent would have handlers
for the extra mime type).

Oddly enough I raised the point about aligning SPARQL to HTTP methods
at the SWIG/DAWG encounter in Cannes, only I really didn't have this
level of granularity in mind. Anyhow, I'm jotting notes on the ESW
Wiki [1].

On an off-topic tangent, talking about HTTP clients and servers in the
same unit - does anyone happen to know whether a Javascript HTTP
server could be embedded in a page/the browser? (Irrespective of
whether this would be sane :-) Any pointers to any post-Ajax
documentation of what approximates the cross-browser Javascript spec
would be appreciated. The agent code I'm playing with is Java, but
there might be fun to be had with server=client (browser).

Cheers,
Danny.

[1] http://esw.w3.org/topic/SemanticWebAgentFramework

-- 

http://dannyayers.com
Received on Saturday, 27 May 2006 09:09:41 GMT

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