[...]... “may be under the control of different ownership domains.” This is a very important point that is often suppressed in SOA definitions You won’t find it in any of the other definitions quoted in this chapter, but it is the key for certain properties of SOA, and a major reason why SOA is not only a technical concept 2.2 SOA DRIVERS 13 SOA includes practices and processes that are based on the fact that... responsibilities include data transformation, (intelligent) routing, dealing with security and reliability, service management, monitoring, and logging Chapter 5 will discuss the purpose and properties of an ESB in detail 18 CHAPTER TWO 2.4.2 Architecture Architecture is necessary to restrict all the possibilities of SOA in such a way that it leads to a working, maintainable system SOA concepts, SOA tools, and SOA. .. understand SOA, you have to understand the properties of large distributed systems First, large systems must deal with legacies You can’t introduce SOA by designing everything from scratch You have to deal with the fact that most of the systems that are in use will remain in use This also means that establishing SOA is not a project like designing a new system It involves changing the structure of an existing... market 1.4 History of SOA Surprisingly, it is hard to find out who coined the term SOA Roy Schulte at Gartner gave me the exact history in a private conversation in 2007: Alexander Pasik, a former analyst at Gartner, coined the term SOA for a class on middleware that he was teaching in 1994 Pasik was working before XML or Web Services were invented, but the basic SOA principles have not changed Pasik... IN FIVE SLIDES 9 1.5.4 Slide 4: SOA in Practice In theory, theory and practice are the same In practice, they are not —L Berra Of course, this also applies to SOA General business cases and concepts might not work as well as expected when factors such as performance and security come into play In addition, the fact that SOA is a strategy for existing systems under maintenance leads to issues of stability... available to other participants in the network as independent services that the participants access in a standardized way Most definitions of SOA identify the use of Web services (i.e., using SOAP or REST) in its implementation However, one can implement SOA using any service-based technology … Unlike traditional point-to-point architectures, SOAs comprise loosely coupled, highly interoperable application... teach SOA I’m still learning every day, but I believe the knowledge I’ve gained so far can help you find an appropriate and successful way to establish SOA and deal with its properties in practice SOA has become a major paradigm, and it now means different things to different people I will concentrate on SOA as a strategy to provide and support distributed business processing In this sense, SOA is... want to use SOA in the context of large distributed systems, explores how SOA emerged, tells the tale of the Magic Bus, and gives a brief overview of SOA Chapter 2, SOA This chapter examines and consolidates the different definitions of SOA and its major properties Chapter 3, Services This chapter examines and consolidates definitions of the many services involved in SOA Chapter 4, Loose Coupling This... complexity, the amount of effort required is low, and things look fine But when this level of complexity is exceeded, the amount of effort required suddenly begins to rise faster than the benefit you gain, and finally, things collapse Too often, SOA is only partly explained and installed Just introducing an infrastructure like Web Services might help up to a certain level of complexity, but this is not enough... these concepts (from a SOA point of view) Structure of the Book The book is designed to be read sequentially, from beginning to end We’ll begin with general SOA concepts, then move on to more advanced topics Cross-references will help you find explanations and further details contained in other chapters and sections, and the index should help you find information and discussions regarding specific topics . History of SOA 7 1.5 SOA in Five Slides 8 2 SOA 11 2.1 Definitions of SOA 11 2.2 SOA Drivers 13 2.3 SOA Concepts 16 2.4 SOA Ingredients 18 2.5 SOA Is Not. Summary 258 19 ESTABLISHING SOA AND SOA GOVERNANCE 261 19.1 Introducing SOA 261 19.2 SOA Governance 262 19.3 SOA Step-by-Step 266 19.4 Other SOA Approaches 271 19.5