Communication between Java Client and Java Web Services on J2EE Platform

In a Web service scenario, a client makes a request to a particular Web service, such as asking for the weather at a certain location, and the service, after processing the request, sends a response to the client to fulfill the request. When both the client and the Web service are implemented in a Java environment, the client makes the call to the service by invoking a Java method, along with setting up and passing the required parameters, and receives as the response the result of the method invocation.
Once the client knows how to access the service, the client makes a request to the service by invoking a Java method, which is passed with its parameters to the client-side JAX-RPC runtime. With the method call, the client is actually invoking an operation on the service. These operations represent the different services of interest to clients. The JAX-RPC runtime maps the Java types to standard XML types and forms a SOAP message that encapsulates the method call and parameters. The runtime then passes the SOAP message through the SOAP handlers, if there are any, and then to the server-side service port.

Java API

Java API for XML-based RPC (JAX-RPC) supports XML-based RPC for Java and J2EE platforms. It enables a traditional client-server remote procedure call (RPC) mechanism using an XML-based protocol. JAX-RPC enables Java technology developers to develop SOAP-based interoperable and portable Web services. Developers use the JAX-RPC programming model to develop SOAP-based Web service endpoints, along with their corresponding WSDL descriptions, and clients. A JAX-RPC-based Web service implementation can interact with clients that are not based on Java. Similarly, a JAX-RPC-based client can interact with a non-Java-based Web service implementation.