XML, Web Services, and the Data Revolution

By Frank  P.  Coyle

Extensible Markup Language (XML) is a simple data description language with profound implications. It affects how we build software and how we think about distributed systems. Surrounding XML is a family of standards and technologies that have opened up new possibilities for exchanging information across the World Wide Web and building communication infrastructures .

XML derives much of its strength in combination with the Web. The Web provides a collection of protocols for moving data; XML represents a way to define that data. The most immediate effect has been a new way to look at the enterprise. Instead of a tightly knit network of servers, the enterprise is now seen as encompassing not just our traditional networks but also the Web itself, with its global reach and scope.

In this chapter we look at XML's role in the expanding view of the enterprise. From its beginnings as a language for describing vertical industry data, XML has blossomed to include not only horizontal applications but also protocols that challenge the conventional wisdom about how to do distributed computing and that open the door to new ways of discovery and connection. Web services represents the most recent visible effect of this change.

In this chapter we also try to establish the context for the changes brought about by XML and the Web. To place events in perspective we explore three technology revolutions: data, architecture, and software. Together the changes in these areas are fostering new ways of thinking about the enterprise and about application development in general. The new paradigm that emerges is the result of global Web-based communication infrastructure, the ability to describe data with XML, and the emergence of XML-based protocols such as Simple Object Access Protocol (SOAP) that contribute to a fabric of loosely coupled distributed systems. As we'll see, these forces are driving initiatives such as Microsoft's .NET and Sun's Java 2 Enterprise Edition (J2EE) that are looking at XML as the bridge between the more traditional space of tightly coupled object systems and the more freewheeling loosely coupled space of the Web.