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[DotGNU]GNU.RDF update 29-3-2003

From: Peter Minten
Subject: [DotGNU]GNU.RDF update 29-3-2003
Date: Sat, 29 Mar 2003 16:06:34 +0100

Hi folks,

on the agenda of GNU.RDF this week:
* Getting GNU.RDF.QL designed.
* Getting the API designed.

I will take care of GNU.RDF.QL .


I made some immediate goals:

* Getting the store up and running in PostgreSQL.
* Getting a basic API running on the server and client. The API should work with
* Getting a basic agent running.


The API will be modular. A small basic API will do the most common stuff and
work with the basic agents. API plugins may extend the functionality, so that
communication with other agents is possible.


GNU.RDF.QL work:

The pointy braces (< >) will be interpreted as a syntax help. They separate
tokens, thus they help the interpreter with seeing the difference between which means a resource with the URI
'' and <>.author which
means the property author of the resource ''. They are
not mandatory in any situation (not even in link paths) but recommended for
clearity when misinterpretations are possible.

The notation property# will mean an element from the collection that is the
value of property. It is used in queries like this:

SELECT people#.fullname
WHERE people#.lastname = "Minten";

which returns all people who's lastname = "Minten" (so only me :-).

This notation is needed to distinguish between the collection and an element
from the collection.

Note that it's also possible to refer to an element from the collection using
[], this works with all collections, it is undefined however which element you
will get from a bag.

In the link path field I've revised the collection element ({...@@...})
selector. The condition now goes first, and if there is a hint it goes behind
the @@. Multiple hints may be given, separated by comma's. The condition can be
a complete RDF query condition since the following: a.b.c{CONDITION}.d.e is
equivalent to:
SELECT c#.d.e
FROM a.b.c
WHERE condition;

This means you can't write in CONDITION 'd.g = "FOO"' anymore, but you must
write 'c#.d.g = "FOO"'. I know it's a little work, but it's much easier when
link paths can be translated into GNU.RDF.QL easily.


That's it for now.



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