In Chapter 6 we established a series of composition and activity management concepts, each with a different scope and purpose, but all somewhat related within the context of composable SOA. Those initial concepts are complemented by additional WS-* extensions that govern specific areas of the SOAP messaging framework, the creation and exchange of metadata, and the introduction of message-level security. (Figure 7.1 introduces the individual concepts and shows how they typically inter-relate.)
Figure 7.1. Specifications and concepts covered in this chapter.
As we explore the various extensions in this chapter, it becomes increasingly clear that SOAP messaging is the lifeblood of contemporary service-oriented architecture. It realizes not only the delivery of application data, but also the composable nature of SOA. The innovation of SOAP headers accounts for almost all of the features covered in Chapters 6 and 7.
To demonstrate common concepts, this chapter borrows terms provided by the following current Web services specifications:
As with Chapter 6, we only explore concepts related to WS-* extensions in this chapter. Language element descriptions and examples for the first five specifications in the preceding list are provided in Chapter 17.
Markup code examples for WS-Eventing and the WS-Notification framework are not provided. These two specifications provide different languages that cover much of the same ground and are more relevant to the subject matter in this book on a conceptual level.
In Plain English sections
This chapter also contains In Plain English sections for every primary concept discussed. Note that these intentionally simplistic analogies continue where they left off in Chapter 6.
How case studies are used: Several of the examples in Chapter 6 are revisited here as we take a closer look at how interaction among specific TLS Web services is affected by the new concepts introduced in this chapter.