Release of the GCX XQuery EngineQ

[Marc Van Cappellen]

As indicated in some other email on this thread, DataDirect XQuery is an
implementation with both document projection as well as streaming
capabilities.

I'm not sure to agree with the "database-oriented" versus
"document-oriented" categorization. DataDirect XQuery supports various
data sources, but it can also be used in "document-oriented" only
applications and is pull-based internally. At the API side, implementing
an XQJ early draft, it offers both SAX (push) and StAX (pull) without
breaking or limiting the underlying streaming capabilities.

Marc

> -----Original Message-----
> From: http://x-query.com/mailman/listinfo/talk [mailto:http://x-query.com/mailman/listinfo/talk] On
Behalf
> Of Per Bothner
> Sent: Monday, February 05, 2007 2:06 AM
> To: Stefanie Scherzinger
> Cc: http://x-query.com/mailman/listinfo/talk
> Subject: Re:  Release of the GCX XQuery EngineQ
> 
> Stefanie Scherzinger wrote:
> > The other in-memory engines (QizX, Galax, and Saxon) implement more
> > XQuery features (or all of them),
> 
> Qexo is also an in-memory engine (though it has an abstraction layer
> to it could potentially hook up to data-base), and open-source
> under a liberal license.
> 
>  > but they are not geared towards stream processing.
>  > ...
> > Unfortunately, no other streaming XQuery implementations are to be
had
> > to be compared against. However, if you know of any suitable
> > implementations, I'd appreciate it very much if you could point us
to
> > them.
> 
> As I see it, there are two kinds of "streaming" implementations:
> - pull-based: expressions are evaluated at-need (lazily) when and if
> their results are needed; or
> - push-based: expressions are evaluated eagerly, but sub-parts of the
> results are "pushed" to a "consumer" as they are generated, while
> avoiding creating of complete "reified" sequences, if possible.
> 
> The "data-base-oriented" implementations seem to be pull-based,
> while more "document-oriented" ones may be push-based.  At least Qexo
> falls into the latter category, and my impression is Saxon does too.
> My impression from your web-page is that GCX is "push-based", so it
> should be comparable to Qexo and Saxon.
> 
> Now Qexo has not been heavily optimized, and it is certainly true
> that there are places where it re-ifies values where it should stream
> them.  Hopefully I'll have time to study your implementation and
> other relevant research so I can do better.
> --
> 	--Per Bothner
> http://x-query.com/mailman/listinfo/talk   http://per.bothner.com/
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