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RE: TAG document: SOAP HTTP GET binding available

From: Sam Ruby <rubys@us.ibm.com>
Date: Tue, 7 May 2002 17:54:01 -0400
To: <www-tag@w3.org>
Message-ID: <OF2D01BEE6.CB04EB56-ON85256BB2.006DC552-85256BB2.00784D53@raleigh.ibm.com>
David Orchard wrote:
>
> 1. It is certainly possible that a web service accessed via GET and URI can
> be exposed as an entry in a wsdl file, and I expect that many would.  But it
> is also certainly possible and probable that web services using URI binding
> or HTTP POST binding without being defined using WSDL.  A key point of this
> proposal is to create an automatable conversion, so that SOAP software can
> reach into URI space.  Given that we want to deal with SOAP in URI space,
> potentially without WSDL, I'm don't see how we could do this as a delta on
> WSDL.

We seem to have a semantic gap here.  Let me start by describing how I use
various terms, and then perhaps we can bridge this gap.  To me, one does
not bind one wire format to another.  Instead one binds of an abstract
definition of a service to (possibly multiple) across-the-wire
representations.

WSDL can be used to describe web services abstractly in the form of
portTypes, as well as binding from portTypes to concrete wire formats.
While there conceptually is a linkage between WSDL and SOAP at design time,
there is *NO* defined linkage from a SOAP datastream to its WSDL
description at runtime.  This, however, does not prevents a an abstract
definition from being constructed and reasoned about.  In
http://radio.weblogs.com/0101679/stories/2002/02/15/aBusyDevelopersGuideToWsdl11.html

I describe how such a description can be provided for a pre-existing
service.

Pre-existing bindings are provided in the WSDL 1.1 specification for SOAP,
HTTP GET, HTTP POST, and MIME.  Given that these bindings already exist - I
am curious as to what problem you have with these existing bindings, and
how your new proposed binding addresses these problems.

> 2. I feel extremely comfortable with the WSDL group looking at the issue of
> defining mechanism for expressing which port-types are "safe".  This would
> be very useful for taking advantage of the proposal.  The TAG would be
> interested in having a discussion with the WSD working group on this.

In WSDL, one describes a service abstractly, and then provides one or more
bindings.  One can simply chose to provide a HTTP GET binding for an
portType, or not.

> 3. I agree with you, clearly the URI binding should be only used for "safe"
> methods.  In fact, the TAG is in a process of issuing a finding on use of
> GET.  This proposal is targetted at SOAP HTTP POST bindings that should be
> expressed in URI space.  One interesting approach would be to label things
> as "safe" in wsdl space, and then use this proposal for providing access in
> URI space.  I purposefully did not include text on using GET for safe
> methods because this text will be in the web architecture document, in
> production.  Perhaps it should be included even though it is duplicating
> information.

I certainly would like to participate in such discussions.

- Sam Ruby
Received on Tuesday, 7 May 2002 17:55:23 GMT

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