What is WSDL ?)

The Web Service Description Language (WSDL) Web Server Description Language is the standard for describing Web services using XML documents. It is the interface definition language of Web Services, proposed jointly by Arba, Intel, IBM, Ms, etc. Through WSDL, three basic attributes of web services can be described:

· What services do-operations provided by services (methods)

· How to access services-data formats and necessary protocols for interaction with services

· Where the service is located-Protocol-related addresses, such as URLs

The WSDL document describes the Web service in the form of a port set. The WSDL service description includes an abstract definition of a group of operations and messages, and is bound to a specific protocol for these operations and messages, A network endpoint specification bound to this instance. The WSDL document is divided into two types: Service Interface and Service implementation. The basic structure of the document is as follows:

 

The main elements in the service interface document are as follows:

Types: defines all data types used by the Web Service and can be referenced by Message Components of the element. It uses a type system (generally the type system in XML Schema ).

Message: an abstract and typed definition of the communication message data structure. Use the type defined by types to define the data structure of the entire message.

Operation: an abstract description of the operations supported in the service. A single operation describes the request/Response Message pairs of an access entry.

Porttype: an abstract set of operations supported by an access entry point type. These operations can be supported by one or more service access points.

Binding: Contains how to transform the abstract interface element (porttype) into the details of specific representation. The specific representation refers to the combination of specific data formats and protocols; binding of specific protocols and data format specifications for specific port types.

Port: a single service access point that combines protocol/Data Format binding with a specific web access address.

Service: This is a rough named element that represents a set of ports and a set of related service access points.

It can be seen that porttype (combined with the details of the message and type elements) describes what the web service is and the binding element describes how to use the web service, the port and service elements describe the location of the web service.

For more information about WSDL, see: http://www.w3.org/TR/