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# WSDL Document * * * A WSDL document is simply an XML document. It contains a set of definitions describing a web service. * * * ## WSDL Document Structure A WSDL document uses the following major elements to describe a web service: | Element | Definition | | --- | --- | | | Operations performed by the web service | | | Messages used by the web service | | | Data types used by the web service | | | Communication protocols used by the web service | The main structure of a WSDL document looks like this: ## WSDL Document Example data type definitions........ definition of the data being communicated.... set of operations...... protocol and data format specification.... A WSDL document can contain other elements, like extension elements, and a service element, which can combine the definitions of several web services into a single WSDL document. * * * ## WSDL Ports The __ element is the most important WSDL element. It describes a web service, the operations that can be performed, and the associated messages. You can think of the element as a function library (or a module, or a class) in a traditional programming language. * * * ## WSDL Messages The __ element defines the data elements for an operation. Each message consists of one or more parts. You can think of these parts as the parameters of a function call in a traditional programming language. * * * ## WSDL Types The __ element defines the data types used by the web service. For maximum platform neutrality, WSDL uses XML Schema syntax to define data types. * * * ## WSDL Bindings The __ element defines the message format and protocol details for each port. * * * ## WSDL Example Here is a simplified fragment of a WSDL document: ## Example In this example, the __ element defines "glossaryTerms" as the name of a _port_, and "getTerm" as the name of an _operation_. The "getTerm" operation has an _input message_ called "getTermRequest" and an _output message_ called "getTermResponse". The __ element defines the _parts_ of each message, as well as the associated data types. Compared to traditional programming, glossaryTerms is a function library, and "getTerm" is a function with an input parameter "getTermRequest" and a return parameter getTermResponse.