Arthur C. Clarke’s third law says;

Any sufficiently advanced technology is indistinguishable from magic

After a busy several days on www-ws-arch I’ve come up with my own version;

Any sufficiently advanced technology is likely to be marginalized

I came up with it to explain the different binding approaches taken by the Web and Web services.

A priori knowledge plus Ex post facto knowledge = Constant

Any suggestions for a name for this principle?

Sean McGrath points out that some folks (himself included) are making predictions for Web services in 2003. It’s surely an oversight that I wasn’t asked for my predictions 8-), so here they are;

  • Web services will continue to struggle on the Internet. XMethods will list only 400 available-over-the-Internet services by the end of the year.
  • The WSA WG will have their architecture document reviewed by the TAG and the Director. One or both of the two will reject it as being incompatible with Web architecture. Much nastiness will ensue.

Sean McGrath calls for a “workable definition” of a Web service in order to bring integration complexity down to O(n) from O(N^2).

While a definition would be a good start, more importantly we need a common abstraction. This drives integration complexity down because once you’ve integrated with one service, you’ve (ideally, and not that uncommonly) integrated with them all.

Take for example, a blog aggregator. If everybody had their own interface to their blog, aggregation would be an O(N^2) task. But luckily they don’t, they all make their RSS available over HTTP GET, a very useful common abstraction. That, plus that RSS (all four versions 8-) is a common format, provides for O(N) integration complexity.

The Web provides one common abstraction that I talk about a lot; the uniform interface. There are others (though none so general, I believe), but Web services, via WSDL, are all about providing custom interfaces. As long as use of WSDL in this manner continues, Web services will, like Sean says, amount to “one big damp squib” (which doesn’t sound like a good thing 8-).