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218 Chapter 29. Web Services with JOnAS
Web Services are generally exposed and discovered through a standard registry service. With these
standards, Web Services consumers (whether they be users or other applications) can access a broad
range of information—personal financial data, news, weather, and enterprise documents—through
applications that reside on servers throughout the network.
Web Services use a WSDL Definition as a contract between client and server (which are called
end-
points ). WSDL defines the types to serialize through the network (described with XMLSchema), the
messages to send and receive (composition, parameters), the portTypes (abstract view of a Port), the
bindings (concrete description of PortType: SOAP, GET, POST, ...), the services (set of Ports), and the
Port (the port is associated with a unique endpoint URL that defines the location of the Web Service).
A Web Service for J2EE is a component with some methods exposed and accessible by HTTP (through
servlets). Web Services can be implemented as Stateless Session Beans or as JAX-RPC classes (a
simple Java class, no inheritance needed).
Figure 29-1. Web Services endpoints deployed within JOnAS (an external client code can access
the endpoint via AxisServlet)
Figure 29-2. Web Services client deployed within JOnAS (can access external Web Services)