Support for web services in EJB 3.0 is based on the Java API for XML-based Web Services (JAX-WS) 2.0 specification, as well its predecessor, the Java API for XML-based RPC (JAX-RPC) 1.1. The name was changed primarily to avoid the common misconception that web services are only about RPC. Other specifications included in EJB 3.0 are the SOAP with Attachments API for Java (SAAJ) and the Java API for XML Registries (JAXR). JAX-WS and JAX-RPC are similar to RMI and CORBA, except they use the SOAP protocol; SAAJ is an API for manipulating the structure of a SOAP message; and JAXR allows you to access web services registries, usually UDDI.
Although this chapter and Chapter 18 provide you with a launching pad for learning about web services in Java EE (specifically EJB), the subject is too huge to cover in a book about EJB. In order to cover Java EE web services comprehensively, we would need another 500 pages. Since you'll need to lift this book to read it, we wrote a lighter approach to the subject. This chapter provides you with an introduction to both JAX-WS and JAX-RPC, but you should not consider it a comprehensive guide to the APIs.
If you are interested in learning more about the standard web services technologies (XML, SOAP, WSDL, and UDDI) and Java EE APIs (JAX-RPC, SAAJ, and JAXR), you might want to read J2EE Web Services (Addison-Wesley), which provides complete and thorough coverage of these topics.
The main purpose of a web services API ...