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Re: WSDL 2.0 issues

From: Dan Connolly <connolly@w3.org>
Date: Tue, 16 Aug 2005 08:56:51 -0500
To: kendall@monkeyfist.com
Cc: DAWG Mailing List <public-rdf-dawg@w3.org>
Message-Id: <1124200611.1045.634.camel@dirk>

On Mon, 2005-08-15 at 14:34 -0400, Kendall Clark wrote:
> Dan, et. al.,
> 
> I've raised some questions about WSDL 2.0, particularly about some of its
> restrictions on serialization types: for inputs outputs, and faults. The
> problems, in a nutshell, are:
> 
> 1. we don't have any other reason to split the SparqlQuery query operation
> into separate operations. It's one operation, from out point of view, that
> may return application/sparql-results+xml or application/rdf+xml. But, near
> as I can tell, WSDL 2.0 requires an operation to return one and only one
> output serialization type. I think that's unnecessarily restrictive and
> means there's a class of useful web services that can't be described.

Yes; it seems there's a requirements mismatch.

Evidently the SPARQL protocol isn't a Web Service, because Web Services
have all their I/O in XML:

"Definition: A Web Service is a software application identified by a URI
[IETF RFC 2396], whose interfaces and binding are capable of being
defined, described and discovered by XML artifacts and supports direct
interactions with other software applications using XML based messages
via Internet-based protocols".
 -- http://www.w3.org/TR/2002/WD-ws-desc-reqs-20021028/

I don't think I had thought that thru when we adopted

3.14 WSDL Protocol
http://www.w3.org/TR/rdf-dawg-uc/#r3.14

Hmm... maybe time to reconsider.

> (We do have the option of taking the default outputSerialization type,
> application/xml, and describing the output of query as XML. Which is
> generally true, but not very specific.)
> 
> 2. Similarly, we have two bindings for that operation, query: one that uses
> GET, with input serialization type application/x-www-form-urlencoded; and
> another that uses POST, where we'd also like
> application/x-www-form-urlencode to be the input serialization type. But as
> I understand WSDL 2.0, it doesn't seem legal to serialize
> application/x-www-form-urlencode to a POST. That, too, seems unnecessarily
> restrictive, though I may be misreading their specs.
> 
> (This is solved by finishing and requiring SparqlX, and while I'm in favor
> of that, I don't see why we can't use WSDL 2.0 to describe a service that
> takes application/x-www-form-urlencode via POST.)
> 
> 3. Last, fault serialization types, as with (1) above, seem to have to be
> one type only. We haven't discussed this issue yet, but I have assumed we do
> not want to specify one and only one Media Type for SPARQL implementations
> to communicate faults, at least on the HTTP side.
> 
> Is that right? If not, we could moot this issue by requiring one and only
> one media type for our faults.
> 
> Kendall Clark
> 
> PS--My message to the WSDL list is
> 
>        http://lists.w3.org/Archives/Public/www-ws-desc/2005Aug/0010.html
-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Tuesday, 16 August 2005 13:56:59 GMT

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