SAX2

XML and Messaging

Most technologies that fueled the “Internet Revolution” of the past few years have been around in one form or another for decades; they were just inaccessible to the volumes of people that were able to use them with mass market web browsers. Some of those technologies are now being re-created: they are updated to work better in today’s Internet, which is a larger and more varied world than the earlier versions they were born into. In this section we will look at why XML is an important part of the re-creation of messaging technologies and at some of the roles Java plays in this process. We also look at how lightweight SAX2-based infrastructure supports XML messaging over the Web without requiring developers to master new toolkits.

XML/Internet Versus Older Technologies

Many more developers work with web servers than have ever worked with Remote Procedure Call (RPC) or message-queuing technologies. However, the problem is largely unchanged: the core issue is still how to exchange messages reliably and securely with services operated by other organizations. The combination of XML and web-based messaging has several basic technical benefits compared to those earlier technology generations, especially most forms of RPC:

HTTP-based protocols have truly global reach

HTTP is in essence a text-based RPC protocol: clients issue requests to objects identified by web server URIs, and those servers dynamically compute the responses. Because it’s text-based, HTTP ...