Everything started to revolve around the concept of the message,
intended as pure data without any logic associated with it. At the time of
this writing, the latest SOAP version is 1.2. The current speci?¬?cation document
explicitly drops the acronym. SOAP is about exchanging messages, not objects.
144 Hints Toward a Solution
WSDL
Once a caller knows that it can use SOAP for communicating, it
needs to know which kind of data the software can handle. The
Web Services Description Language (WSDL) absolves that function.
Documents written in WSDL describe the operations exposed
by a web service and the message format required (and
returned) for every function provided. The idea of an explicit
contract is very important in software development and in web
services and service orientation is possibly even more important.
However, further discussion of such is beyond the scope of this
book. For a comprehensive coverage of the topic, consult
Understanding Web Services(Newcomer, 2002).
WS-Addressing
In Chapter 1, in the section ???HTTP,??? we saw how web page
addresses work. The address http://www.bob.com/bob/
homepage.htm tells the browser to use the HTTP protocol for
retrieving the HTML document homepage.
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