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Java and SOAP by Robert Englander

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9.1. Web Services Definition Language

One way to avoid interoperability problems with SOAP-based services is to use a structured language to describe the service, its location, the service methods, parameters, data types, and so on. The Web Services Definition Language (WSDL) does just that. WSDL is an XML grammar for describing web services. Systems can determine the programmatic interface of a web service by looking at the WSDL document associated with that service. The document describes the service methods along with their parameters and return types, and may also include the address, or endpoint, of the service. One of the greatest benefits of WSDL is that it is a single, accepted standard[1] for describing web services, which among other things motivates SOAP developers to avoid using their own mechanism for that task.

[1] You can find the WSDL specification at http://www.w3.org/TR/wsdl.

Does WSDL eliminate the problems associated with human (or machine) interpretation? Well, not completely. It does mean that service descriptions are far less ambiguous than they would be if there were no standard, but on the other hand, WSDL has a specification of its own, and that specification has the potential to be interpreted differently by multiple parties. WSDL isn't a perfect solution, but it certainly puts those of us working with these technologies in a better place than we'd be in otherwise.

9.1.1. Overview of WSDL

We're not going to cover WSDL in detail, as it's a large subject ...

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