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Re: [DotGNU]RDF Query Language


From: Peter Minten
Subject: Re: [DotGNU]RDF Query Language
Date: Wed, 26 Mar 2003 19:12:35 +0100

Danny Ayers wrote:
> 
> > Not really. Those languages are quite complicated. RDF is simple
> > and thus the
> > query language can be simple. My approach is to keep things simple.
> 
> Not similar? Your version :
> 
> The basic SELECT operation goes like this:
> SELECT propertynames
> FROM resourceclassnames
> WHERE condition
> GROUP BY propertynames
> HAVING condition
> 
> an example from RDQL [1] :
> 
> SELECT ?a, ?b
> WHERE  (?a, <http://somewhere/pred1>, ?b)
> AND    ?b <

SQL is easy to understand, GNU.RDF.QL attempts to be easy to understand too.
Somebody who does not know GNU.RDF.QL but only RDF should be able to get the
idea of a GNU.RDF.QL query straight away, don't think they will be able to do
the same with RDQL. One lesson that can be learned from the current unpopularity
of LISP is that syntax matters, a lot.

> If you believe the language (RQL or RDQL) as a whole is too complicated,
> then you could define a subset. I still don't see any reason to invent a
> completely new language and with it new interop problems.

Hmm, interop problems, not really. The GNU.RDF.QL is mainly used to communicate
with GNU.RDF servers. It has the advantage of being quite close to the actual
database layout. If I would ever need to communicate with other kinds of servers
I would simply create a conversion agent. 

> > Anyway time to rename my query language: GNU.RDF.QL :-)
> 
> Good name ;-)
> 
> Cheeers,
> Danny.
> 
> [1] http://www.hpl.hp.com/semweb/rdql-examples.html




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