snelson.org.uk/john

I've been doing quite a bit of work on Faxpp recently. My enthusiasm had kind of ground to a halt for a while after I realised the full complexity of implementing entities, but then I decided I just needed to knuckle down and get it finished. The fruit of my labours can now be downloaded from Sourceforge.

I think I've got a robust framework for resolving and parsing internal and external entities - and I've learnt things about XML that I'm not sure many people in the world know:

• Parameter entities ("%entity;") can appear almost anywhere in an external subset (DTD), but their replacement value is substituted with an extra leading and trailing space if the reference isn't in a literal value.
• Character references in entity values are expanded when the entity declaration is parsed, but general entity references are not resolved until the entity value is substituted for a reference.
• An XML 1.0 DTD referenced by an XML 1.1 document will be parsed as though it were XML 1.1.
• At least two thirds of the code in an XML parser is there to support functionality that 90% of XML documents never use.

I can also lay claim to actually understanding what notations are, although I don't think I'll ever find a use for them.

I'm calling this release a beta, because I know there's still a bit of work left to be done. Top of the list is implementing default attribute values, then maybe I'll get to work on shrinking the parser - since the DTD parsing code has made it much larger than I want it to be.

Oracle officially announced the XQilla license change today. It feels like this has been a long time coming - I was involved in pushing for the original Pathan project to be open sourced in 2003 when I worked at Decisionsoft. Later when I worked for Sleepycat, I was involved in pushing for a liberally licensed release of the XQuery implementation and improvements to Pathan which became XQilla some 3 years later.

It's great to see something that I've worked on for the last 7 years start to get the exposure I always thought it deserved. XQuery has huge potential to change the way that people use their data, and it's close relationship to the web means now might be the right time, and XQilla might be in the right place.

Thanks has to go to Mike Olson who put in the lion's share of the work needed to make this happen. Hopefully his efforts will make it easier for even more Oracle code to reach it's potential by being released as open source.

I've just finished the application process for XQilla to be a part of Google Summer of Code 2008. I'm always coming up with way too many projects to do, and there's never enough time to get around to all of them - the ideas list we've put together has some of the most interesting and self contained of those projects. Take a look if you fancy learning more about XQuery, open source or XQilla.