Re: [Qexo-general] Interface between XQuery-Engine and XML-DB

[Per Bothner]

Maik Thiele wrote:
> I want to write an interface that is able to read data from a native
> XML-Database (likely eXist), processing the data in a XQuery processor
> and write the result back to the database. I think that should be 
> possible with Qexo as the XQuery processor or do you see a problem that 
> I overlook?

If you plan to read the data and write the result back as text/xml,
it would be fairly straight-forward.  The hooks are there for
reading and writing data using SAX2, but this isn't quite
complete, and hasn't been tested, though it shouldn't be very
difficult.  You'll have a slightly easier time using Qexo's
native Consumer interface.

Note input() and collection haven't been implemented - they
are obvious very implementaton- and application-specific.

> To improve the performance I want to delegate the XPath parts of an
> XQuery down to eXist. So the document that need to be transfered
> to Qexo would be much smaller. Is there any possibility to do this?

It's quite possible.  I'd write a class in Java that acts as an
XQuery function whose result is the filtered output.  Your class
would emit calls to the Consumer that Qexo provides.

> Furthermore, do you have some papers that describe the XQuery
> processing of Qexo in detail. Which classes are involved?

Not really.  What I have is either accessible from
http://per.bothner.com/papers/
or
http://www.gnu.org/software/qexo/
--
        --Per Bothner
address@hidden   http://per.bothner.com/