Chapter 6: Building a Web Services Call

Overview

When it comes to designing and building Web services, there are two levels of difficulty: Web services calls and Web services workflows. Every request made to a Web service initiates a Web services call. The response from the provider then completes that interaction. A Web services workflow consists of a series of interdependent, if not sequential, Web services calls.

Obviously, before moving on to the workflows, we need to be able to build a Web services call, and that's what this chapter is all about. We will take a couple of existing processes and turn them directly into Web services. Vendors are putting much of their effort into defining how to build Web services from scratch, but a lot of existing functionality that's available today could extend their value as Web services. These examples will illustrate exactly how this can be done.

Our first example will take an existing Java class-an amortization calculator-and expose one of its public methods. Then we will take an existing COM object that provides weather updates and expose it. We will then complete the chapter by taking one of these services and adding security and authentication through the use of client certificates.

Note 

These two examples accommodate very different skill sets and expertise, so my expectation is that most readers will not follow along and build both of these Web services. Some developers are experienced with both environments, but, if you are not, you won't learn them from just this chapter! Although lessons can be learned from reading through both examples, my recommendation is to try to implement only the environment(s) that you are familiar with.