Re: New issue [distobj@acm.org: Re: What does WSDL describe?]

On Fri, 24 Oct 2003 12:00:52 -0400
Mark Baker <distobj@acm.org> wrote:

> On Fri, Oct 24, 2003 at 11:07:35AM -0400, Amelia A. Lewis wrote:
> > Perhaps this could be summarized as:
> > 
> > ISSUE: should WSDL operations be restricted to state transfer only?
> 
> Well, that would certainly resolve my issue! 8-)  But I'm not
> suggesting that WSDL be restricted to state transfer, only that for a
> given service, that the service be able to specify which it's using
> (fwiw, this is closely related to issue 64, but more general).
> 
> But sure, I'm also hoping that by explaining the differences between
> message exchange and document exchange, that folks will begin to see
> some of the value in REST, and that it's useful for more than just
> browsers.

It is not difficult to regard any particular instance of web services as
REST.  It only requires regarding the WSDL as a resource.

If WSDL is a resource, then a client, upon obtaining that resource, has
acquired certain information about the state of the service. 
Specifically, it has acquired information about the formats required for
further state transfers to and from the service.

The state contained in each of the follow on messages may then include
both data specific to the client ("12345"), and data from a subset of
the communicated state of the service (selecting a verb, e.g. "add").

Or, in other words, a part of the state transfer from client to service
includes the verb, selected from among those which the service has
advertised as available.

This is a richer form of REST than that enshrined in RFC2616.  It
provides a means for communicating the verbs to be used in state
transfer as part of the mechanism (except that it doesn't actually
define how one goes about acquiring a WSDL).  One could argue that it is
*more* RESTful than HTTP, since it treats the verbal vocabulary as
just-another-bit-of-state.

Don't you just hate it when people twist things up like that?  *laugh*

Amy!
-- 
Amelia A. Lewis
Architect, TIBCO/Extensibility, Inc.
alewis@tibco.com

Received on Friday, 24 October 2003 12:41:14 UTC