You have already deployed POJO components into ServiceMix and exposed them as services. An external client can invoke the POJO services by sending SOAP requests and receiving back the SOAP responses. At times, you may also need to deal with non-SOAP formatted, but plain XML messages. We also need to stream such messages too through firewalls to the bus and get them processed.

This chapter showed you how we can do this using XStream. Some legacy integration scenario might warrant this approach. You might also have noted the fact that we can replace the XStream used in this sample with any other Java XML binding framework such as Castor or XMLBeans, but XStream's advantage is the built-in integration XStream has with the ServiceMix JBI.

The ServiceMix JBI bus provides a framework for many lightweight integration libraries like XStream. It also realizes many design patterns used in software engineering like the well known Proxy pattern which we will explore in the next chapter.