Generically, a service contract defines the interface to a service, informing consuming client applications what they must send to it (the type and structure of the input data) and what they can expect to receive in return (the type and structure of the output data). If a service contract conforms to a standardized format, it can often be analyzed by consuming applications, which can then generate, populate and send compliant service requests automatically.
Web Services standards define two such service contract formats, the Web Services Description Language, or WSDL (sometimes pronounced wiz-dull) and the XML Schema (sometimes known as an XSD because of its file extension, .xsd). Because both the WSDL and XSD are physical documents describing the service contract for a specific Web Service, they are known as explicit service contracts. A Java service may also have a service contract, or interface, but no standard description exists for an explicit service contract. Therefore, most service contract discussions in this chapter relate to Web Services deployments only.
Depending on the choice of architecture made earlier, you have two options when representing data in a call to Corticon Server: an XML document or a set of Java Business Objects.
