Chapter 11. Implementing a process engine in the ESB

 

In this chapter:

  • Using a process engine for stateful flows
  • Ensuring a clear separation between an ESB and a process engine
  • Implementing a case study with jBPM and Mule
  • Implementing a case study with Apache ODE and ServiceMix

In the previous chapters, we’ve discussed different functionalities of open source ESBs including routing, transformation, connectivity, and transactions. These functionalities focus on integrating services and applications with message flows. Most of these message flows are stateless, which means that no state is preserved after the message has been routed through the open source ESB. The stateless characteristic of message flows is also an important aspect for an ESB to be able to scale when needed.

But in some scenarios, you want the state to be preserved during multiple message flow invocations. The time that passes between these message flow invocations can be days or even weeks in some environments, so you need an additional component to implement stateful flows.

11.1. Introducing the process engine

11.2. A process engine case study: booking a day of scuba diving

11.3. Diving into the messages and services

11.4. Implementing a process engine with jBPM and jPDL

11.5. Implementing a process engine with Apache ODE and WS-BPEL

11.6. Summary