[xml] XPath 2, XSLT 2

[Steve Ball <Steve Ball explain com au>]

First the good news: I've started working on implementing XPath 2 in  
libxml2 and XSLT 2 in libxslt. The first thing I've tackled in XPath 2  
is sequences. The library can now parse the following expressions and  
returns the correct result:

count(("a", "b", "c"))            := 3
count(("a", 2, 3.0, "d"))           := 4
count(/)                                        := 1
count(/*)                                       := 1
count((/*))                             := 1
count((/, /*))                          := 2
count((//p, //chapter))         := 7

xmlSequence has been added as an object type, in addition to the  
existing types, including xmlNodeSet and value tree. The reason for  
this is to maintain backward-compatibility (which is require for XSLT  
backward-compatible processing mode). The existing XPath APIs  
implement XPath 1 syntax and semantics. I've added a new API to create  
an XPath parser with XPath 2 syntax. This means that existing  
applications will need to be updated to use XPath 2; by default they  
will continue to use XPath 1.

On the XSLT 2 front I've started work on implementing xsl:for-each- 
group. Of the four grouping algorithms the first to be implemented  
will be group-adjacent. From the work I've done with XSLT 2 so far,  
this feature is one of the most profound improvements over XSLT 1, so  
there will be a lot of bang for the buck.

Now for the not bad, but interesting news! Since no one else is  
volunteering their time to do this work, I've decided to see if anyone  
will volunteer their money instead. I've setup a project within my  
company to undertake this development and to fund it we are offering a  
suite of professional services. You can read more details about this  
at http://www.explain.com.au/libx/.

When the XPath 2 and XSLT 2 implementation has been completed all of  
that code will be contributed back to the Gnome libxml2/libxslt  
project. In the meantime, to get early access to the code you can sign- 
up for our Professional Developers Programme, see http://www.explain.com.au/libx/programmes.html 
. You can join as an individual, or businesses can join up to get  
access for multiple employees. The more people and businesses join up,  
the more resources I'll have to further work on the XPath 2/XSLT 2  
implementation.

Reporting on progress to the general community with messages like this  
one will be irregular. However, there will be a regular and detailed  
reports to members of the Professional Developers Programme.

Once the implementation is complete I'm planning on going further by  
creating a product that offers features beyond those in the XPath and  
XSLT standards. This will include transparent features, such as  
performance optimisations, as well as custom extensions. I'll know the  
code pretty well by then, so providing professional services, such as  
support, customisations and application development, won't be too  
difficult.

I hope the community finds my approach to funding this work  
acceptable. If you don't like it, then feel free to send me a message  
(preferably along with an offer to help). If you don't mind it but  
don't have the money then feel free to send a message of encouragement  
(and tell your friends and neighbours to sign up ;-).

Regards,
Steve Ball