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Building Web Services with JAX-WS

<< Part 3. Web Services | Setting the Port >>
<< Part 3. Web Services | Setting the Port >>

Building Web Services with JAX-WS

Building Web Services with JAX-WS
JAX-WS stands for Java API for XML Web Services. JAX-WS is a technology for building web
services and clients that communicate using XML. JAX-WS allows developers to write
message-oriented as well as RPC-oriented web services.
In JAX-WS, a web service operation invocation is represented by an XML-based protocol such
as SOAP. The SOAP specification defines the envelope structure, encoding rules, and
conventions for representing web service invocations and responses. These calls and responses
are transmitted as SOAP messages (XML files) over HTTP.
Although SOAP messages are complex, the JAX-WS API hides this complexity from the
application developer. On the server side, the developer specifies the web service operations by
defining methods in an interface written in the Java programming language. The developer also
codes one or more classes that implement those methods. Client programs are also easy to code.
A client creates a proxy (a local object representing the service) and then simply invokes
methods on the proxy. With JAX-WS, the developer does not generate or parse SOAP messages.
It is the JAX-WS runtime system that converts the API calls and responses to and from SOAP
messages.
With JAX-WS, clients and web services have a big advantage: the platform independence of the
Java programming language. In addition, JAX-WS is not restrictive: a JAX-WS client can access
a web service that is not running on the Java platform, and vice versa. This flexibility is possible
because JAX-WS uses technologies defined by the World Wide Web Consortium (W3C):
HTTP, SOAP, and the Web Service Description Language (WSDL). WSDL specifies an XML
format for describing a service as a set of endpoints operating on messages.
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