Re: Is This a Web Service?

I have used the following terms to label a spectrum of Web service types:

Custom Web Service: Uses an interface description (e.g. WSDL), but all 
other WS specs are optional (e.g. it doesn't have to use SOAP, HTTP , 
etc... this could be nothing more than a WSDL description of a Java RMI 
interface, for instance).... some would hesitate to call this a Web 
service (me included... but I've stuck to the use of the term "Web 
service" here so that it fits in with existing nomenclature)

Internet Web Service: Uses an interface description (WSDL) + standard 
internet protocols (e.g. HTTP).  All other things (e.g. SOAP) are 
optional.

Interoperable Web Service: Uses an interface description (WSDL) + standard 
internet protoocls (e.g. HTTP) and SOAP.  Generally talking about WS-I 
basic profile conformance.

The point is, no, Web services should not be required to use SOAP to be 
considered Web services.  At a barest minimum, they should require nothing 
more than a WSDL service description.

- James M Snell
  jasnell@us.ibm.com
  http://www.ibm.com
  (877) 511-5082 / Office
  930-1979 / Tie Line



"Cutler, Roger (RogerCutler)" <RogerCutler@ChevronTexaco.com> 
Sent by: www-ws-arch-request@w3.org
04/14/2003 02:19 PM

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Subject
Is This a Web Service?






The recent conversation has included the interesting idea of looking at 
Web services as SOAP services.  Are we really saying that SOAP is integral 
and required for ALL Web services?  For example (and this is a real 
example), suppose there is a Web site on the internet that is oriented 
toward returning results to people on browsers, but if you set the 
parameters of the GET in a particular manner it runs an application that 
generates an image (the nature of which depends on other parameters) and 
returns that image (and only the image) as an HTTP type image/png.  I now 
have an application that at some point wants to make such an image with 
the contents based, shall we say, on calculated values (in fact, this 
determines text that is inside the image, if you must know) -- and I do a 
GET with the appropriate parameters, wait for the HTTP to come back, write 
the binary stream of the image somewhere and go about the business of the 
application which does something with the image.
Now, I personally think that's a Web service, mostly because of the 
application to application flavor.  I would not call it a "W3C Web 
service", since it doesn't use WSDL and SOAP -- but it seems pretty Web 
service-ey to me.  I would personally call it an "ad hoc" Web service -- 
and I would make up another name for ebXML transactions that use SOAP but 
not WSDL, since it seems to me that those, too, are Web services that 
handle the description differently. 
But what do you folks think?  Does it absolutely have to use SOAP to be a 
Web service?  If so, that's an interesting and really useful thing to 
know.  My personal opinion, for what it is worth, is that simpler, ad hoc 
things like the example above are, indeed, Web services, but you quickly 
start needing SOAP if you want to do anything other than the most basic 
operations, and so in practice most of the "interesting" Web services use 
SOAP.  I am certainly willing to agree that if a Web service uses ANY 
enveloping mechanism that it should be SOAP, since there don't seem to be 
any other real popular candidates.  Is that a reasonable point of view?