One of the SOA characteristics we identified in Chapter 3 is that it is in a state of evolution. To fully appreciate this quality we need to take a look at what industry developments are influencing SOA today and the overall direction SOA is headed.
This chapter examines the relationship between XML, Web services, and SOA and explains how vendors and standards organizations have formed a strangely competitive and collaborative arena from which Web services specifications are continually surfacing. We then conclude by embarking on a short historical recount of application architecture over the past two decades.
The sequence of topics in this chapter may seem a bit odd. We begin with recent and current developments and end with a look at past architectural platforms. This structure was chosen simply because the information in the last section of this chapter may not be of interest to everyone and is not considered required reading.
How case studies are used: This chapter provides us with an opportunity to better establish the existing environments within our two fictional companies. Upon the conclusion of each of the architectural comparisons, examples are provided describing details of legacy applications from RailCo and TLS.