Web Service Orchestration without BPEL

In my project there is a requirement to call few web services in sequence and aggregate the responses and expose the functionality as a web service. There are quite many services with this required behavior. The initial solution was to use some BPEL engine, but the decision was put on hold due to various reasons and we were encouraged to whip up a light weight framework in java that suits our needs. This was indeed interesting and I was successful in designing and developing a embeddable and light weight orchestration framework in java. Following are some thoughts on the same -

Since, the framework is more or less chaining of web service calls, I decided to keep the flow of messages as XML inside the orchestration framework. Modeled the Orchestration as an XML pipeline. Chaining of web service calls needed transformation of response to that of the request of the next service and XSL has been choosen to transform the message formats. Quickly whipped up an XSLUtil based on Trax (Transformation API for XML). The next challenge was to invoke the webservices using XML data as request. I decided to go the XML way to avoid marshalling/unmarshalling of POJOs from/to XML. JAX-WS came handy here. JAX-WS comes with a nice feature called Dispatch that would allow invocation of web services using either a SOAP message or XML payload, the latter met my need. It didnt take much time to play with the Dispatch interface and to implement a generic utility. I had the core componenets ready in a very short span of time.

The next step was to abstract the execution of these utilities, so defined the classes called *Action for transformation and invocation and made them configurable using a XML file and my little orchestration framework is ready. It also has a feature that reports the invocation trace along with the profiling information. However, this is just the beginning. There was an immediate need to add the branching, looping, assignment actions. Used JEXL for expression evaluation of branching and looping functions. And now, am thinking of adding some kind of a transition governance between the stages (using AspectJ) and add some kind of a compensation handlers to each stage. I'm also playing around with XTS of JBossTM to see if I can provide transaction recovery and make the web services transaction aware.

If you have any suggestions and ideas to improve the framework, write a comment.

Qualities of a Software Architect

Interesting article on the essential qualities of an architect. Read it here -
http://blogs.msdn.com/gabriel_morgan/archive/2009/01/17/enterprise-solution-architects-and-leadership.aspx.I quite agree with Gabriel that leadership is imperative for an architect. Let me know your thoughts.