Re: Steps you can do in XSLT (Was:Comments from the XSLT WG on the XProc Last Call Document)

Hi Jeni,

These are my private thoughts rather than a position the XSL WG.

Jeni Tennison wrote:
> If I remember rightly, our decision was to support full expressions and
> patterns, and treat the detection of streamability as an optional
> optimisation.
>
> There were three reasons for this. First, it would significantly delay
> XProc if we had to define which patterns/expressions are streamable and
> which aren't. 

This is of course a valid argument I can accept. I do understand that
you have your time line and the first version of any language cannot
consider all peripheral use cases.

> Second, it would force users to learn which
> patterns/expressions are usable in XProc and which aren't, raising the
> barrier to use. 

Yes, but on the other hand, leaving streamability as an optimization
means that users working with large document will not benefit from the
standardization of XProc. They will be bound to a specific optimized
processor, and they will need to understand internals of the processor
to know whether their pipelines are streamable (and thus working) or
not. These people would be happy to know that some patterns are
guaranteed to be streamable by XProc processors claiming streaming
friendliness.

This is of course a new level of complexity but I believe it worths to
be considered for the next version. XProc is in a very good position to
enable streaming processing and I think it would be a loss to miss this
prospect.

> Third, it would mean XProc implementers would have
> to specialise XPath libraries to only work on the streamable subset,
> raising the barrier to implementation.

Another point of view is that this is an opportunity for implementers to
deliver a more value to users. Most existing implementations of XML
technologies optimize much more complex patterns, hence I would not be
that much concerned about implementers in this case.


Best Regards,
Petr

-- 
Petr Cimprich
Project Manager

U-Turn, a.s.
Mercury Business Centre
Argentinská 38/286

170 00 Prague 7

Czech Republic

http://www.u-turnmediagroup.com

Received on Thursday, 1 November 2007 08:56:35 UTC