WSDL uses abstract and specific descriptions to describe web services. While the abstract description refers to the functionality of the service, the specific description conveys clear facts such as the transmission protocol. The document (i.e. the WSDL file) has a hierarchical structure. Information is therefore nested.
WSDL adopts six main elements from XML:
- types: data types
- messages: description of the data to be transmitted
- interface: abstract operations which describe the communication between the server and client (was still called portType in an older version of the standard)
- binding: information about the transport protocol used
- endpoint: information about the communication interface, usually in the form of a URI (was still called port in an older version of the standard
- service: access points of the web service
By filling in all the elements in the file, the client gets all the information needed to use the web service. This is precisely why a web service is platform-independent, because the different systems receive the common language through the WSDL file.