Chapter Fifteen. SOAP, WSDL, and UDDI, Oh My...Web Services Foundations and Application Integration

So, you want to do Web services? This chapter talks about the foundation standards: SOAP, WSDL, and UDDI. What's important about these Web services components is the fact that most vendors (IBM, Sun, BEA, Microsoft, etc.) can agree upon these standards as the foundation for their own Web services strategies; thus, we have the chance of interoperability.

Be clear that we will focus on how these standards apply to the notion of application integration. There are hundreds of books that provide additional information in much more detail. Also note that there will be more opinion in this chapter than in the other chapters on standards.

Web services is the latest notion to take the information system development world by storm as major vendors (including Microsoft, HP, and Sun) announce their Web services strategies. The press promotes Web services as the biggest paradigm shift since the Web itself. At the same time, rank-and-file IT professionals are trying to understand just what Web services are, and assess their value within the enterprise and application integration.

The idea of Web services is exciting: the ability to create new applications by aggregating the services of many other applications that exist locally or remotely on the Internet. However, there are a number of issues to consider when looking at Web services:

1. Keep in mind: This is an old idea with new wrapping. If you remember the promise of distributed objects of almost a decade ago, the concept is the same: provide the infrastructure for applications to exchange information, as well as leverage methods encapsulated within those applications. Web services simply put a newer, sexier architecture and enabling technology into the mix most importantly, adding the word "Web."

2. Standards overload still prevails. As in the days of distributed objects, vendors see a hot space emerge, and all stake their own claims in the Web services space, publishing their own proprietary standards that they call "open." Thus, a shakeout is inevitable before we understand which standards will become "standard." This will only delay acceptance of Web services. Today, caution is needed from those who look to address application integration using Web services. Things could change and they may be stuck holding the bag.

Despite the usual drawbacks of emerging technology, Web services at least the notion of Web services is an interesting technology for the world of inter- and intracompany application integration. Web services hold the promise of moving beyond the simple exchange of information the dominating mechanism for application integration today to the concept of accessing services that are encapsulated within old and new applications, in and between companies. This means we can not only move information from application to application, but also create composite applications, leveraging any number of back-end application services found in any number of applications, local or remote.

Key to this concept is figuring out how Web services fit into the existing application integration technology and approaches. For example, when is the use of Web services appropriate, and how do we determine cost-effectiveness? Keep in mind: Implementing Web services is bound to be an invasive process, thus expensive when compared to enabling systems for simple information exchange. For more information on how Web services fit with application integration, see Chapter 4 on Service-Oriented Application Integration.