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RE: why query languages and RDF data have syntaxes?

From: Charles McCathieNevile <charles@w3.org>
Date: Sun, 1 Dec 2002 02:48:22 -0500 (EST)
To: Graham Klyne <GK@ninebynine.org>
cc: "Seaborne, Andy" <Andy_Seaborne@hplb.hpl.hp.com>, "'jeffzhang726@yahoo.com.cn'" <jeffzhang726@yahoo.com.cn>, "'www-rdf-interest@w3.org'" <www-rdf-interest@w3.org>
Message-ID: <Pine.LNX.4.30.0212010235330.664-100000@tux.w3.org>

From a programmer's perspective it seems that people are interested in query
syntaxes that look like SQL, although from time to time there is value in
replicating RDF syntax and just leaving blanks to fill in. This approach is
reasonably intuitive to people who understand the syntax in the first place -
more so than learning SQL. But many of us on the web are not really familiar
with neither SQL nor RDF syntaxes.

Tools such as RDF Author, IsaViz, foafnaut, etc suggest that we can make
straightforward interfaces for people that use a visual or logical syntax
rather than a strictly written one, using good interface design to present
the logical model to people without making them learn arbitrary syntaxes.

As an inermediate layer, then, we still have two different approaches,
meaning that authors of interfaces for people have to work out two ways of
matching them to query engines.

Is this diversity a good thing because it enables different kinnds of users,
or just ebcause it enables different programmers to develop systems easier,
or is it a problem?


Charles McCN

On Fri, 29 Nov 2002, Graham Klyne wrote:

>At 09:30 AM 11/29/02 +0000, Seaborne, Andy wrote:
>>I think the query languages you have looked at are trying to address the
>>problem of getting information out of an RDF model.  They appeal to the
>>common SQL paradigm and provide a programming structure that application
>>writers are familiar with.  In particular, the result of a query is a set of
>>variable bindings, not a gragh (or set of graphs).  Having such a syntax for
>>a query is convenient - building queries as an RDF model in a toolkit of
>>your choice is a bit tedious.
>Yes, building queries as an RDF model can be tedious, though I do think it
>has some advantages.  That is what I do in my toy query language [1].  I
>find it convenient that there is only one input syntax that my software has
>to deal with, but you're right that the queries can be a bit tedious to
>code.  (I've thought about writing a separate query-to-RDF/N3 compiler ;-)
>I entirely agree about the variable binding issue, which is another reason
>that it's not always sufficient to use an RDF example directly as a query.
>[1] http://www.ninebynine.org/RDFNotes/RDFForLittleLanguages.htm
>Graham Klyne

Charles McCathieNevile  http://www.w3.org/People/Charles  tel: +61 409 134 136
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Received on Sunday, 1 December 2002 02:49:28 UTC

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