Consolidation on web services description
09:31, 26 Sep 2000 UTC | Edd Dumbill

IBM, Microsoft and Ariba have published Web Services Description Language 1.0 (WSDL), replacing earlier attempts by Microsoft and IBM at such a technology.

The three companies are also instigators of the UDDI effort for "universal description, discovery and integration of business for the web."

WSDL supersedes both Microsoft's SOAP Contract Language, SCL, and IBM's NASSL, to provide a single XML format for describing network services (a third competitor format, James Snell's SIDL, was withdrawn earlier this year in favor of Microsoft's SCL). The specification introduces its scope as:

... describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint.

However, WSDL is not the complete solution to describing network services. The authors state that they intend to publish revisions of the spec to accomodate:

... means for composing services and means for expressing the behavior of services, i.e. the sequencing rules for sending and receiving messages. Composition of services must be type safe but also allow for reference passing with service references being exchanged and bound at runtime.

WSDL itself makes extensive use of namespaces, and the spec provides a W3C XML schema for the language. Use of WSDL with SOAP is illustrated.

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