Operating systems -- and in particular their GUIs -- maintain structured, persistent data through a variety of mechanisms and in a variety of formats. Windows versions used INI files, then moved to a binary (and unified) registry; eariler versions of Mac OS had resource forks in the file system and a desktop file for its Finder; Linux and other UNIX-like systems typically used dotted, hidden files in home directories, with configuration detailed in dozens of incompatible ways between window managers and applications.
The Java APIs for XML-Based Remote Procedure Call (JAX-RPC) protocol (see Resources) is Java-centric, not WSDL-centric. It contains a fairly elaborate set of rules for mapping WSDL names to Java-friendly names which follow the Java coding conventions. This is good because JAX-RPC users will be Java programmers. In fact, they may not even care that your Web service is a Web service. They probably do not know or care about WSDL and XML, and all the quirks that they bring to the table. All they may care about is that they can write Java code to call your service and expect the JAX-RPC APIs for your service to look familiar; in other words, to follow Java coding conventions.
XML (eXtensible Markup Language) is not a programming language. Like HTML (and sharing a common parentage - but that's another story), XML is a means of 'marking up' the content of a document using elements (sometimes referred to as tags) to mark the beginning and end of sections of information.
In this article, I show you how you can extend a Web service, defined by WSDL, by adding SOAP headers. I show how SOAP handlers create and process SOAP message headers and how to configure handlers appropriately.
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