Monthly Archives: July 2003

Kendall Clark on Choreography

Lancelot: He says they've already *got* one!
Arthur: (confused) Are you *sure* he's got one?
Soldier: Oh yes, it's ver' naahs.
  -- Monty Python and the Holy Grail

Kendall writes;

In principle I support WS-Choreography, even without understanding exactly what it is aiming at, if only because it is likely to be very RDF and REST friendly, and those are, all other things being equal, among my preferred ways of describing information and building information interfaces.

That's good to hear, but I really don't see choreography solutions being anywhere near REST friendly. REST has already got a ver' naahs choreography solution built-in; hypermedia. It's how a REST agent changes state. As Roy wrote;

The model application is therefore an engine that moves from one state to the next by examining and choosing from among the alternative state transitions in the current set of representations.

XML Catalogs and caching

Norm responds to a post of mine about why I felt that better technology, and not necessarily new standards, were what was required to solve the problems that XML Catalogs were trying to solve.

He offers three things that he believes can’t be done with caches, but can be done with XML Catalogs;

Populate the cache. “Caching proxies rely on the fact that you can access the resource at least once from the web.”. wwwoffle does this, but a better caching system need not. When I talked about the need for operating systems to be in on caching (and later with the Save-As idea), what I had in mind was treating the computer’s storage as a structured store (remember Bento?), such that any content would hit the disk “named” with its URI. This would permit the software that Norm installs to include with it a representation of this resource (schema or whatever), named with its one true URI, and available to any app on that machine. Again, no new standards required.

In that same section, Norm says that sometimes the URI may never be directly resolvable. That is definitely a possibility, but again, this same mechanism of tightly associating the URI-as-name with the data, makes that mostly moot; it doesn’t matter where the data comes from (modulo trust) if it’s self-describing.

Access Development Resources. Yah, what Mark said.

Devise Your Own Resolution Policies. I think your comment about public identifiers is relevant here; if they were used, this wouldn’t be an issue, and caching would be useful.

But while I maintain that better technology can do what Norm needs, I’m not saying that no standardization was necessary. Due to the fact that the technology is not there to do what is needed, plus the extent to which that technology needs to pretty much be pervasively integrated into OSs, standardizing on XML Catalogs may very well have been the best option. But something tells me that the decision to standardize was made without knowledge that a technical solution existed. No biggie, just pointing that out 8-).