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

[Peter Minten]

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
XML-RPC and GNU.RDF.QL .
* 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
http://foo.com/bar.html.author which means a resource with the URI
'http://foo.com/bar.html.author' and <http://foo.com/bar.html>.author which
means the property author of the resource 'http://foo.com/bar.html'. 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
FROM http://dotgnu.org/people
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.

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That's it for now.

Greetings,

Peter