WSDL Used In Web Services

Defining WSDL?

WSDL [Web Services Description Language ] is an XML-based language for describing and accessing Web services.

WSDL is an XML based language , written in XML, that provides a model for describing Web services.

Although WSDL is not yet a W3C standard, it is widely adopted to locate and describe Web services.

WSDL pronounced 'wiz-dull' or spelled out, 'W-S-D-L'.

WSDL Versions

WSDL Version 1.1 - released version, has not been endorsed by the World Wide Web Consortium (W3C).

WSDL Version 2.0 - drafts released, is expected to become a W3C recommendation.

How WSDL Is Used

WSDL defines services as collections of network endpoints, or ports. WSDL specification provides an XML format for documents for this purpose.

The abstract definition of ports and messages is separated from their concrete use or instance, 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 often used in combination with SOAP and XML Schema to provide web services over the Internet.

A client program connecting to a web service can read the WSDL to determine what functions are available on the server. Any special datatypes used are embedded in the WSDL file in the form of XML Schema.

The client can then use SOAP to actually call one of the functions listed in the WSDL.

XLANG

XLang is an extension of the WSDL.

An XLANG service description is a WSDL service description with an extension element that describes the behavior of the service as a part of a business process.

Resources

Reference: Wikipedia

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