An Introduction to WSDL

A brief introduction to WSDL and how it is used by the Citrix NetScaler API framework.

Summary

WSDL (pronounced as Wiz-Del) stands for Web Services Description Language and is an XML document that is used to locate and describe web services.

The WSDL defines web services as collections of network endpoints, or ports. The abstract definition of ports and messages is separated from their actual values, allowing the reuse of these definitions. A port is defined by associating a network address with a reusable binding, and a collection of ports define a service. Messages are abstract descriptions of the data being exchanged, and port types are abstract collections of supported operations. The concrete protocol and data format specifications for a particular port type constitutes a reusable binding, where the messages and operations are then bound to a concrete network protocol and message format. In this way, WSDL describes the public interface to the web service.

WSDL is most commonly used with SOAP and XML to make these services available over the Internet. A client program that wishes to use the web service can read the WSDL to determine what functions are available. The client then uses SOAP to call one of the functions listed in the WSDL and use the web service.

The following elements are used in a WSDL document to describe web services

The following is an overview of the structure of a WSDL document

<definitions>
    <types>
        type definitions
    </types>

    <message>
        message definitions
    </message>

    <portType>
        port definitions
    </portType>

    <binding>
        binding definitions
    </binding>

</definitions>

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