i was trying to formulate my thoughts about clay's recent web services: it's so crazy, it just might not work. on the one hand, it's a great hype-deflating piece, with quotes like:

"Web Services can't create a framework in which any two arbitrary applications can interact because XML doesn't provide shared languages, merely shared alphabets. The Web Services stack pushes this shared semantics problem into higher and higher layers without solving it. Humans often cannot create perfectly transparent descriptions even when they are trying to, and they simply won't try when there's an economic incentive to stretch the truth."

on the other hand, the piece can also be viewed as an overblown version of that oldie, but goodie - xml and semantic transparency:

"We may rehearse this fundamental axiom of descriptive markup in terms of a classical SGML polemic: the doubly-delimited information objects in an SGML/XML document are described by markup in a meaningful, self-documenting way through the use of names which are carefully selected by domain experts for element type names, attribute names, and attribute values. This is true of XML in 1998, was true of SGML in 1986, and was true of Brian Reid's Scribe system in 1976. However, of itself, descriptive markup proves to be of limited relevance as a mechanism to enable information interchange at the level of the machine.
As enchanting as it is to contemplate the apparent 'semantic' clarity, flexibility, and extensibility of XML vis-à-vis HTML (e.g., how wonderfully perspicuous XML <bookTitle> seems when compared to HTML <i>), we must reckon with the cold fact that XML does not of itself enable blind interchange or information reuse. XML may help humans predict what information might lie "between the tags" in the case of <trunk> </trunk>, but XML can only help. For an XML processor, <trunk> and <i> and <booktitle> are all equally (and totally) meaningless. Yes, meaningless.

Just like its parent metalanguage (SGML), XML has no formal mechanism to support the declaration of semantic integrity constraints, and XML processors have no means of validating object semantics even if these are declared informally in an XML DTD. XML processors will have no inherent understanding of document object semantics because XML (meta-)markup languages have no predefined application-level processing semantics. XML thus formally governs syntax only - not semantics."

ahhh. but how to complain and yet not appear to be approving of the hype? well, julian bond does a fine job:

"I think the commentators and practitioners in the web services space are in danger of promoting the same sort of muddy thinking. We're setting up a straw man by focussing on one aspect of the problem in order to provide an excuse to pull down the whole edifice."

so the business process semantics of arbitrary application to application communication isn't really on the event horizon. point taken - even by the analysts:

"According to Gartner, more than 40 percent of enterprises' first experience with the technology will be an internal deployment of a Web services-enabled architecture. Almost without anyone recognizing it, Gartner says, applications will move from a code-and-recode model to one of connect, disconnect and reconnect dynamically.

"Setbacks should be presumed, particularly in vendor interoperability conflicts, but ensuing layers of metadata and ad-hoc collaboration at low levels should ensure 'good enough' solutions," said Daryl Plummer, group vice president and research group director for Gartner."

[update] hmmm. coincidence or not. clay just posted a message to decentralization that clarifies the point that i was trying to make:

"This is one of the points I was trying to make -- this stuff is a tool for developers to work out the details of application interop. It is not a tool to create interop out of thin air."