I just ran into Tim Bray’s “Sharecropper” blog entry. Tim writes;
You’re not a sharecropper, especially not a sharecropper, if you’re building on the Web platform. If you can define your value-add as a series of interactions via a browser, or an interchange of XML messages, nobody can whip the land out from under you.
If you want to understand self-description, look no further than that last sentence fragment, “nobody can whip the land out from under you”. What that means is that the semantics of the message are grounded entirely in the realm of public specifications. I don’t happen to believe that “XML messages” are necessarily very self-descriptive, and I’d expect Tim to agree; I’m sure he was just over simplifying.