[On the Topic of Resouces and Services] FW: [xml-dev] What Does SOAP/WS Do that A REST System Can't?

["Chiusano Joseph" <chiusano_joseph@bah.com>]

Forwarding this semi-recent XML-DEV posting by Mike Champion regarding
resource-orientation vs. service-orientation. He references an XML.com
article by Joe Gregorio that expands on this topic.

Joe 

Joseph Chiusano
Booz Allen Hamilton
Visit us online@ http://www.boozallen.com

-----Original Message-----
From: Michael Champion [mailto:michaelc.champion@gmail.com] 
Sent: Wednesday, March 30, 2005 12:50 PM
To: xml-dev@lists.xml.org
Subject: Re: [xml-dev] What Does SOAP/WS Do that A REST System Can't?

On Wed, 30 Mar 2005 12:32:11 -0500, Joe Gregorio
<joe.gregorio@gmail.com> wrote:

> > Mu.  REST is a protocol, SOAP is a message format.  <duck>
> 
> REST is an architectural style, SOAP is a message format.

You're right of course.  SOA is also an architectural style.

  I *think* the whole SOAP vs REST permathread  comes down to
Resource-orientation vs Service-orientation ... complicated by the fact
that services are also resources, and services can be invoked by
HTTP+XML just fine.  Joe's
http://www.xml.com/pub/a/2005/03/02/restful.html  is the clearest I've
ever seen on what "resource orientation" means :

" we need to answer our four questions.
   1. What are the resources?
   2. What are the representations?
   3. What methods are supported at each resource?
   4. What status codes could be returned?"

I can't point to an equally concise definition of SOA, perhaps something
like:
   1. What are the services?
   2. What are the the service contracts (interfaces) to invoke the
servces?
   3. What quality of service is required in a real business situation?
   4. What technologies can be feasibly applied to meet those QoS
requirements?"

In *both* REST and SOA there is a very large hairy wookie of an
unanswered question screeching for attention: What are the semantics of
the resources / services?  In practice this is handled explicitly or
implicitly by human understanding in both styles. In theory both could
be handled by some sort of formal semantic mapping a la the Semantic
Web.

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