A Web Service (commonly called a service) comprises some content, or some process, or both, with an open programmatic interface. Simple examples: currency converter, stock quotes, dictionary. More complex examples: travel planner, procurement workflow system. Two key parts of the Web Services infrastructure are WSDL, a language for describing Web Services; and SOAP, a protocol that enables applications an Web Services to communicate. For an overview of Web Services, see the Concepts section of the Using Web Services tutorial.

A client communicates with a Web Service via a request-response protocol, and an endpoint represents the ultimate destination of a client request, providing an interface to the service's methods. The EJB 2.1 specification defines a mechanism whereby a bean provider can make a stateless session bean available to Web Service clients. This support for Web Service endpoints in EJBs makes it easy for developers to integrate J2EE applications with Web Services.

The provider implements a JAX-RPC (Java API for XML-based remote procedure calls) interface to the bean and exposes it to clients via WSDL. Implementation details are transparent to the client, which interacts with the bean as it would with any other Web Service.