Release of the GCX XQuery EngineQ

[Stefanie Scherzinger]

Hello Michael,

thanks for your interest in GCX.

Regarding your comments on query rewrites: Yes, we've restricted
ourselves to a maneagable syntactic fragment of XQuery for a start,
and we're confident that the fragment can be extended. The static
query rewriting which inserts the "signOff-statements" into queries
from our fragment is already implemented in our engine.

> As far as I can see, what they have done is a useful development that takes
> further the idea of document projection put forward by Marian and Simeon,
> which is already being exploited in industrial products such as DataDirect's
> (though not yet in Saxon, regrettably). This work also, incidentally, is
> likely to convince any sceptics that a language with restricted expressive
> power compared to XSLT is capable of being optimized to a much greater
> extent than XSLT is, which helps users in understanding the trade-off
> between the two languages.

Thanks for the pointer to DataDirect, I didn't know they had
projection implemented. I've been looking a bit into optimization
techniques for DOM trees, and came across the TinyTree model from
Saxon. I  was wondering whether you plan to keep extending it.

Steffi