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e hënë janar 31, 2005

Re:Syndication model convergence and RDF

Cool, Danny Ayers discovered our little java-syndication group and wrote a thoughtful blog entry with a proposal for something that we want to solve: Syndication model convergence and RDF.

2 weeks ago Alejandro and I (from ROME) went to San Francisco to have lunch with Kevin Burton and Brad Neuberg from Feedparser and discussed potential areas of collaboration, and our joint submission at JavaOne. One of the ideas that came up (from Brad if I remember) was to build ROME-like beans on top of a Feedparser-like event driven API. We also agreed that the first thing we could collaborate on was on specifications for the mapping. After lunch I suggested that we could eventually move the mapping logic (in ROME terms, how you map a format specific WireFeed to an abstract SyndFeed) to a declarative representation, so that instead of having written specs we could generate code. But I didn't elaborate much more: I was not sure it would be necessary if we build one parser on top of the other. Most of the logic would migrate in feedparser, to generate the Synd level event, and ROME would just listen to these events to build beans.

What I had in the back of my mind when suggesting that was linked to my recent dabbings in Ruby. A quick look at the Ruby Application Archive showed 3 syndication libraries:

ruby-rss, antique, from 2001, probably only good for RSS 0.91
rerss, last updated in 2003, good for RSS 1.0 and 2.0.
rss, last updated in december, this seems to be the live one. It handlles RSS 1.0, 0.9x/2.0 with validation (or non validation), but not sure about generation, no Atom, and not sure about the object model.

If I write my next system in Ruby I'll need a ROME-like library, except if I run on top of a VM and use JRuby. I thought it would be a waste of time to completely recreate ROME in Ruby. If the mapping rules expressed in ROME source code were expressed declaratively I could rewrite ROME by parsing and interpreting it, as a test case for the description. Then Feedparser could do the same, but more importantly syndication libraries written in other languages such as Ruby could do the same: as a programmer, you could go from one system to the other and still work with the same object model for feeds, entries and modules.

I had not started thinking about which format to use for this description, but Henry Story's work on mapping Atom to OWL (continuing the work Danny had started) leapt to my mind (he presented it at the october 21st ossgtp in Paris). Danny fills in the blanks in his post! I wanted to spend a bit more time looking at alternative formats and tools for this description (RelaxNG, XMLSchema?) before starting on that, but this application seems to me like an excellent real world use case of RDF/OWL.

( Jan 31 2005, 09:55:44 PD PST ) Permalink Chat about it