A Service Description plays an important role in enabling access to a service. Most service description languages are designed for machine consumption, allowing for the automatic creation of code skeletons, easier search, and classification of services. However, people may also find descriptions useful to learn about the use of parameters or the precise semantics of some operation.
There are several aspects in data description like the definition of the data structure, of the type and values, its semantic etc…
For XML, XML Schema provide structural, type and values descriptions; For Web Services, WSDL provides, via the use of XML Schema, the data formats flowing in and out; SAWSDL provides a way to add semantic descriptions to XML Schema and WDSL descriptions.
WSDL defines not only the format and values of data flowing in and out of the service, but also define the endpoints, supported operations, message exchange patterns (MEP), everything relative to the operative description of the Web Services endpoints.
WS-Choreography describe the flow of messages between a set of services participating in a global choreography of exchanges, without having a controller. It can also be used to validate a posteriori a serie of logged exchanges between different parties.
WS Policy describe the policies in use when accessing a service, through policy assertions, like security policies, transport protocol selection, etc…
See the XML Schema Primer.
Learn more about the current status of specifications related to:
These W3C Groups are working on the related specifications: