Java Reference
In-Depth Information
3 Web Service De-
scription Language (WSDL)
Objectives
After reading this chapter, you should:
1.
Possess a basic understanding of a WSDL
2.
Be able to decipher a WSDL
WSDL assists service clients that need to know how to bind a service automatically.
A service contract must be established between the service consumer and provider. A
published WSDL describes in detail the contract, which may include messages, operations,
bindings and locations of the service.
When a Web Service is ready for use, its location and access are made known to external
systems. WSDL is based on the Interface Description Language (IDL), which describes the
interface of a software component for other components to use. In RPC, a developer defines
an interface of a component to be exposed to external applications that do not share the
same language.
Once an interface is described, in most cases, a tool is used to generate client and server
stubs for the client side and the server side, respectively, to use. The server application uses
the server stub for its implementation of the service, while the client application uses the
client stub for its service invocation.
3.1 WSDL structure
WSDL consists of two parts: abstract interface and concrete implementation. While the ab-
stract interface describes the operations and messages of a service, the concrete implement-
ation part binds the abstract interface with a concrete network address. Thus, the two to-
gether comprise a service.
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