Introduction

Overview

In the film Tron, an evil force called the Master Control Program gains strength by systematically assimilating other programs across the worldwide networks. The Terminator depicts the same sort of hostile takeover mentality: the Terminator’s creator, Skynet, gains consciousness as scientists hook together systems around the world and these systems begin to work together. While we all hope that such scenarios won’t prove to be prescient, in the spirit of mutual trust and cooperation we’re still trying to open up the terabytes of legacy data and the functionality of current systems to a worldwide network. The obstacles we face in this effort might not have indestructible exoskeletons like Arnie’s, but we still haven’t solved the problem of how to connect the dozens of incompatible operating systems, protocols, and file systems.

One possible solution lies with XML Web services. The idea of augmenting your applications, whether desktop or Web-based, with online information has long since been put into practice. From news sites that share daily headlines with each other as RSS feeds to more interesting ideas like Philip Greenspun’s Wealth Clock (http://philip.greenspun.com/WealthClock), developers have been propagating and using online resources since 1995.

Resource sharing and system interoperability have gained tremendous importance over the last few years, but the basic ideas for achieving those goals have remained the same during that time. Those goals are just a bit easier to achieve today. Amazon.com, for example, provides a set of Web services to retrieve book information directly from its databases so we don’t have to scrape it off book pages with regular expressions. Requesting data from Amazon.com is still a matter of sending text over the wire, but the text now means more than “Give me the following page.”

The beauty of keeping this more meaningful interaction between online applications spelled out in simple text is in its inclusiveness. Any system—current or legacy— can send text over the wire, and as long as the meaning of the text is understood, we have the basis for universal system interoperation. The potential of this approach is so great that Microsoft has thrown its weight behind the advancement, making Web services a focal point of the Microsoft .NET Framework. Together with companies such as IBM and Sun Microsystems and the open source community, Microsoft is pushing us toward a Web services utopia.