Decentralyze

Here’s another middle-of-the-night-while-travelling post. It’s about OWL….

Last week, the W3C OWL Working Group decided that it was essentially done with the design of the OWL 2 language. All that remains is some editorial work and fixing bugs that might crop up. In W3C process terminology, the Working Group decided it was (mostly) ready for “Last Call” of its multi-part specification. Happily, it’s pretty much on-schedule

I’ve been the primary W3C staff contact for this Working Group, and I was the secondary staff contact for the OWL 1 Working Group for its last six months (back in 2003-2004). I’ve tried to support both groups however I could, in infrastructure, process advice, management advice, and in some limitted areas with technical design advice. But, awkwardly, I’m not really an OWL user, so I sometimes feel like this OWL work is only my “day job”.

That’s okay — lots of us do things for work that we’re not passionate about — but it isn’t how I usually operate. More interestingly, it’s kind of odd. I mean, OWL is on the very short list of Semantic Web standards, and I’m quite passionate about decentralization, which is more-or-less what the Semantic Web is about. So why am I not passionate about OWL?

Personal Reasons?

Okay, there may be some personal reasons. I’ll describe them in the hope of factoring them out, and in the hope of generally learning more about how people interact with standards committees.

1. Although I was involved fairly near the beginning of work on OWL, I still feel late-to-the-party. For me, when I’m late to a party, I tend to have a nagging feeling that I missed something important, and I stay very cautious. I’m less likely to become enthusiastic.

2. Perhaps because of that, or perhaps because I’m not a Description Logics researcher, I don’t feel like part of the “in-crowd” — even though I know and like and feel personally comfortable with many people who are.

3. I don’t think I could ever get into the top tier of experts in either OWL implementation or OWL usage. There are some very, very smart people who have been dedicated to those subjects for years already. I doubt I could catch up.

These wouldn’t stop me from being an implementor (I did one strange OWL implementation called surnia) and/or user, but it makes it harder for me to feel ownership. Maybe that’s related to excitement.

Technical Reasons?

The important issue here, though, is technical. Is OWL important for decentralization? Perhaps it is, but I’m not convinced. Really, my gut says “no”, the experts say “yes”, and I’m just confused. And so we end up with a blog post.

What purposes might OWL serve?

1. It might be a data interface definition language, along the lines of BNF, ASN.1, and XML Schema, except on some subtley-different level. Decentralized systems certainly need something like this — some computer format for defining the interfaces — but is it OWL? (cf my work last year on asn07 (rif wiki, rif e-mail)). Some people tell me it’s entirely unsuitable for this; some people say they’ve been using it for this for years.

2. It might give people some computer support for defining a vocabulary, something like a spell-checker helps people writing prose. I have the feeling this is where the core Ontology community is. In this view, OWL is there to help you find errors and get insights into your vocabulary specification (aka your ontology).

3. It might be used as a declarative programming language for expressing Semantic Web shims, the transformations needed so systems using related-but-different RDF vocabularies can interoperate. But maybe this is better done with RIF or conventional programming languages? This is the Ontology Mapping problem. Clearly OWL isn’t expressive enough to do all kinds of mapping, and it probably is the best option for trivial kinds of mapping (stuff that just uses owl:sameAs), but what about everything in between?

Sometimes in standards work there is constructive ambiguity in the spec and also in the charter. It makes the technology easier to sell, and draws in a wide base of potential support. What is this technology for? Well, it’s for lots of things. It might be just what you need! If the charter were more specific, picking out only points 1, 2, or 3, then we’d have a narrower spec, serving a narrower community. Maybe serving it better, but still with fewer economies of scale and network effects.

If we look back at the OWL Use Cases and Requirements, we see use cases somewhat in line with these three options, although taking a rather different approach. The first two are about using automated reasoning in mapping between vocabularies; that’s sort of number 3, but with human vocabularies à la wordnet. The other four are less clear cut. Number five look like classic decentralization, but I don’t see any case being made for OWL in there. Number six looks like classic planning; is OWL the best logic language for automated planning?

Anyway, I’d love to hear comments (below or via trackback/pingback) about what
you think OWL is good for.

[Oh, look, it sounds like there’s some interesting discussion of this going on at OWLED. A shame I wasn’t up for travelling three weeks in a row.]

Please note that I’m really not complaining about OWL. I’m fairly comfortable with it’s design, and quite happy with the design process. I’m just saying that I have trouble seeing why it’s as cool as some people seem to think it is. Maybe I’m missing something. Maybe my goals are different. Maybe it’s utility is exactly the same to both of us, and for whatever reason it doesn’t turn me on the same way. I’m just trying to understand that….