Conclusion
This article set out to define what an ESB is, what it consists of, and what problems it is designed to solve. As a result you, should have and understanding of when to use an ESB, and what parts best apply to your own problem sets. An important lesson to learn is that the ESB should be thought of as a toolkit, or a framework, from which you can choose the pieces to use or ignore as you design and build distributed software systems.
For existing systems, the ESB can be easily migrated to, or it can be used to integrate existing systems and services, even when those systems were not originally designed to work in a service-oriented architecture. Although the ESB is built around XML and SOA technology, through adapters and message normalization, legacy systems of all types can be brought into the modern age of integration and Web 2.0 architectures.
Furthermore, the case studies and the sample application presented here should begin to give you a feel for how an ESB is put to use, how it can benefit your organization, and how it can save time and money from a design, development, and administrative point of view