It seems to me that John, in his eagerness to use microformats, reinvents the idea of a standardized structured format. We had that with SGML, we have that with XML. You don't need to use XML Schema to work with XML. In fact, (and Tim may confirm or deny this), XML seems like it's intended to be usable for these signposts John speaks of - recognized names would be my interpretation. Granted, microformats have their advantages and disadvantages over XML.Jacek, I do know these things. I've worked with SGML and XML for years at Isogen, and Eliot Kimber taught me many important things about markup, including SGML Architectures (which interesting could provide an avenue to formalize microformats into fully defined markup languages). (Anyone have a link to SGML Architectural Forms?)
Thing is, I'm not really that interested in those details. Yes, they are important, but the distinctions between a DTD, RelaxNG, XML Schema, micro-format, and XLink don't make this issue any different.
On the topic of REST: only some commonly understood format is important. It's my personal opinion that any of the schemas I described in my previous post should be described in RelaxNG, XSD, and an HTML micro-format (with an SGML Architecture for good measure!).
My point is that multiple clients should be able to easily describe what must be followed and inspected, or what must be acted upon and triggered.
Jacek, I think we agree that IDL should not be dismissed. I'm trying to define a declarative definition that support better machine processing that fits into the constraints of the Web.
The Web has one Interface. Trying to write an IDL against that one interface (URI, HTTP Methods) is either very boring or is trying overlay domain methods onto HTTP methods.
I'm trying to find a way to describe web interfaces to machines. Hard coding URIs isn't good because of all the stuff people say. So, we add some special data (I'm not ready to say metadata) to some of the HTML forms to let a machine know which form should be used to buy something instead of logging out.