Java API for XML Web Services (JAX-WS) is a Java technology for building web services and clients that communicate using XML. JAX-WS allows developers to write message-oriented as well as Remote Procedure Call-oriented (RPC-oriented) web services.

In JAX-WS a Web Service invocation is represented by a SOAP message. On the server side the developer creates an interface for exposed methods and provides implementation for those methods in some classes. Client creates the proxy and simply invokes methods on the proxy. JAX-WS API completely hides the complexity of SOAP from the application developer. The developer does not generate or parse SOAP messages. The JAX-WS runtime system converts the API calls and responses to and from SOAP messages.