Part 4. Event stream processing, integration, and mediation

In the previous five chapters we focused on the services aspect of SOA. We described how services can be easily developed using the Service Component Architecture and its implementation using Apache Tuscany. Then, using JBoss jBPM, we illustrated how such services can be combined to create entire business processes that can be modeled and executed, representing a new form of application development. In part 4, we’ll switch gears a bit and discuss the role of the enterprise service bus (ESB), an important enabling technology for SOA. An ESB can act as middleware “glue” for integrating with systems, applications, and protocols that weren’t necessarily designed with the precepts of SOA in mind. An ESB can act as a mediator for bridging differences in protocols, provide service transparency, and perform data transformations. In addition, it can be used to advance the cause of governance by enforcing service and security usage profiles. Related to this is event stream processing (ESP), which can be used to detect any unusual patterns of activity and provide real-time notification to the appropriate business users. We’ll begin part 4 by examining the role of ESP in chapter 8, and you’ll learn how to analyze complex business events using Esper, an outstanding open source ESP product.