[MOBY-l] further thoughts on atomic services & service description

[Mark Wilkinson]

Martin Senger wrote:
 >>Can you define "web service" for me, as it seems that we might be
 >>chasing our semantic tails here...
 >>
 >
 >    I mean Web Services as defined by w3c (http://www.w3.org/2002/ws/).


A quote from that page:
----------------------------------------------------
The generalized term "Web services" does not currently describe a 
coherent or necessarily consistent set of technologies, architectures, 
or even visions. The community of Web services evangelists, architects, 
developers, and vendors represents a merging of at least three major 
sources of inspiration, with various ideas taken from other sources as 
well. Several streams of thought and practice have converged to produce 
an amalgam of what we think of as "Web services", including:
     *      "Distributed Objects" or "Application Integration" -- 
exchange of programming objects or invocation of software functions over 
a network.
     *      EDI / B2B - the exchange of electronic business documents 
over a network.
     *      The World Wide Web itself - accessing human readable 
documents and posting requests for information, products, or services 
via the HTTP protocol.
------------------------------------------------------


... which is why I asked the question what do *you* mean by Web Services 
  ;-)

Here's what I think you mean - please correct me if I am wrong:

I think you are defining a "web service" as "a SOAP interface that is 
described by a WSDL" ("is" being the operative word, rather than "can 
be").   I would agree that WSDL is becoming the de facto standard for 
describing web services, but I disagree that it is the *only* way to 
describe web service interfaces.  Nevertheless, I don't think there is 
any disagreement that WSDL is what we will use in MOBY, and that every 
MOBY service will be representable as WSDL. I believe, therefore, that 
all MOBY services are web services by your definition... if I am 
interpreting your definition properly.

But philosophically speaking, MOBY services are not "web services" (by 
this definition) until they are actually *called*, since in MOBY the 
WSDL doesn't exist until the service definition is requested from MOBY 
Central... ahhh... existence!  We're playing God here!

I'd like to point out, however, that this is not part of the  most basic 
W3C definition of a web service, as indicated in the note below:

-----------------------------------------------------
2 What is a Web service?

Although there are a number of varied and often seemingly inconsistent 
motivations for, and uses of, the term "Web service", at its core, the 
following definition captures what we believe to be the shared essence 
of the term:

[Definition: A Web service is a software system identified by a URI, 
whose public interfaces and bindings are defined and described using 
XML. Its definition can be discovered by other software systems. These 
systems may then interact with the Web service in a manner prescribed by 
its definition, using XML based messages conveyed by internet protocols.]

This definition serves as the basis for the architetcure described in 
this document.

Note:
Our definition of the term "Web services" does not presuppose the use of 
SOAP as a packaging format or a processing model. Nor does it presuppose 
the use of WSDL as a service description language. There are, and will 
be in the future, plenty of Web services that use raw HTTP as a data 
transfer protocol and some mutually agreed-upon XML format as the 
message content. The Web Services *reference architecture* does, 
however, assume that the higher levels of the Web services protocol 
stack are built on the foundation of SOAP and WSDL.
-------------------------------------------------------


In any case, philosophy aside, I think we are safe in saying that MOBY 
services, and eventually MOBY Central, will be Web Services in the 
strictest sense :-)

M




-- 
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"Speed is subsittute fo accurancy."
________________________________

Dr. Mark Wilkinson, RA Bioinformatics
National Research Council, Plant Biotechnology Institute
110 Gymnasium Place, Saskatoon, SK, Canada

phone : (306) 975 5279
pager : (306) 934 2322
mobile: markw_mobile at illuminae dot com