Web Services Description Language (WSDL)

Web Services Description Language (WSDL) is a format for describing a Web Services interface. It is a way to describe services and how they should be bound to specific network addresses. WSDL has three parts:

bulletDefinitions
bulletOperations
bulletService bindings

Definitions are generally expressed in XML and include both data type definitions and message definitions that use the data type definitions. These definitions are usually based upon some agreed upon XML vocabulary. This agreement could be within an organization or between organizations. Vocabularies within an organization could be designed specifically for that organization. They may or may not be based on some industry-wide vocabulary. If data type and message definitions need to be used between organizations, then most likely an industry-wide vocabulary will be used. For more on XML vocabularies, click here

XML, however, is not necessary required for definitions. The OMG Interface Definition Language (IDL), for example, could be used instead of XML. If a different definitional format were used, senders and receivers would need to agree on the format as well as the vocabulary. Nevertheless, over time, XML-based vocabularies and messages are likely to dominate. XML Namespaces (new window) are used to ensure uniqueness of the XML element names in the definitions, operations, and service bindings.

Operations describe actions for the messages supported by a Web service. There are four types of operations:

bulletOne-way: Messages sent without a reply required
bulletRequest/response: The sender sends a message and the received sends a reply.
bulletSolicit response: A request for a response. (The specific definition for this action is pending.)
bulletNotification: Messages sent to multiple receivers. (The specific definition for this action is pending.)

Operations are grouped into port types. Port types define a set of operations supported by the Web service.

Service bindings connect port types to a port. A port is defined by associating a network address with a port type. A collection of ports defines a service. This binding is commonly created using SOAP (new window), but other forms may be used. These other forms could include CORBA Internet Inter-ORB Protocol (IIOP), DCOM, .NET, Java Message Service (JMS), or WebSphere MQ to name a few.

The following figure shows the relationship of the basic parts of WSDL:

Also see XML vocabularies (new window).

Organization: W3C

More information: WSDL page on the W3C Web site (new window)

Related content for: Web Services Description Language (WSDL)

More on the general topic: Service
Web Services Policy Framework (WS-Policy)
Web Services Dynamic Discovery (WS-Discovery)
Web Services Metadata Exchange (WS-MetaDataExchange)
Web Services Endpoint Language (WSEL)

Read more free articles on this site

There are nearly 400 pages of articles on this site with over 130 pages on Web services and service-oriented architecture.

Search this site for more articles

Custom Search

Browse this site for more articles

Click on the topics below to browse the articles on this site.The arrows show the path to the current article: Web Services Description Language (WSDL).

 

Newletter Sign Up

 

 

Barry & Associates, Inc.