28.2. Web Service Basics

The machine on which a web service resides is referred to as a web service host. The client application sends a request over a network to the web service host, which processes the request and returns a response over the network to the application. This kind of distributed computing benefits systems in various ways. For example, an application without direct access to data on another system might be able to retrieve the data via a web service. Similarly, an application lacking the processing power to perform specific computations could use a web service to take advantage of another system’s superior resources.

In Java, a web service is implemented as a class that resides on a server—it’s not part of the client application. Making a web service available to receive client requests is known as publishing a web service; using a web service from a client application is known as consuming a web service.