Web services are a very resilient and powerful tool in the enterprise architecture toolbox. They were born from the marriage of XML, a very flexible data formatting language, with HTTP and other similarly ubiquitous communication protocols.
There have been a few generations of “web services” over the years. XML-RPC was arguably the first XML-based services scheme that was used widely, and it is still available today in various programming environments. More recently, a standard set of protocols for XML-based services has been defined and adopted by the software community. The primary protocol in this family is the Simple Object Access Protocol (SOAP).
In this chapter, we cover the standard APIs used in Java for implementing and using SOAP-based web services. These include the Java API for XML-based RPC (JAX-RPC) and the SOAP with Attachments API for Java (SAAJ). We will cover the versions included in the J2EE 1.4 specification, and that translates to JAX-RPC Version 1.1 and SAAJ Version 1.2.
We will also be discussing the Web Services for J2EE specification, Version 1.1. This API is also required in J2EE 1.4 servers and defines a standard deployment model for web services within a J2EE environment.
This chapter begins with a general overview of web services and the SOAP and Web Service Descriptor Language (WSDL) protocols that modern-day web services use predominantly. The bulk of the chapter, though, discusses how ...