Catching ideas

On November 26, W3C announced that XProc has moved the Candidate Recommendation status.

For those who don’t know what XProc, or XML Pipeline Language, is, I think it’s best to quote the specification:

[XProc is] a language for describing operations to be performed on XML documents.

An XML Pipeline specifies a sequence of operations to be performed on zero or more XML documents. Pipelines generally accept zero or more XML documents as input and produce zero or more XML documents as output. Pipelines are made up of simple steps which perform atomic operations on XML documents and constructs similar to conditionals, iteration, and exception handlers which control which steps are executed.

The specification is maintained by the XML Processing Model Working Group, which I happen to be a member of. The group is chaired by Norman Walsh, who – in parallel to his great editorial work (and I mean it, Norm; it has been a pleasure for me so far!) – is also responsible for the development of Calabash, the reference XProc implementation.

My involvement with XProc (and the WG) began in early 2008, when I started implementing an XProc processor for my employer. Since then, the specification has undergone a number of changes of varying magnitudes, so at times it was quite a challenge to keep our implementation in sync. But I endured (hey, I get paid for that!), and now I am happy to see that both Calabash and our – yet unnamed – processor are getting more mature every day.

At the moment, one of the most important tasks for the WG is to come up with a comprehensive test suite that would cover most of the language. And the sooner we are done with this the better, since the test suite not only helps to guarantee a reasonable level of interoperability among XProc implementations, but the whole process of writing test cases helps us to detect and fix defects or ambiguities in the specification until there is still time. There are quite a number of tests already, and I would say we are somewhere halfway through, so there is definitely still some work to be done… But we are making good progress, I think, and we will get there, soon.

In the meantime, feel encouraged to get in touch with us at the xproc-dev@w3.org mailing list. It is the perfect place to find out more about XProc and to ask questions. You can subscribe by sending an e-mail with the subject subscribe to xproc-dev-request@w3.org. See you there!