Mediation and Orchestration

If you are in a real project knowing the difference between mediation and orchestration is important.
In my previous blog entry I gave a short introduction into the different types of processes.
If found some interesting articles that provide more detailed information about the subject.

A good article written by Satadru Roy about mediation and orchestration can be found at
SOA infrastructure: Mediation and orchestration

Another one written by Ronan Bradley is:
ESB: saving SOA from a dead end

Differentiation of Processes

With the advent ot Service-oriented Architecture (SOA), processes are getting more and more into focus.
If you talk to people with different backgrounds about processes, you’ll likely get different definitions which often causes confusion.

The web developer

The web developer sees processes as a series of dialogs or web pages.
These web pages are connected to guide the user to carry out a certain task such as ordering a book in an online bookshop.
Technologies to connect web pages are Beehives Page flow, Struts or Java Server Faces (JSF).
These kind of processes are refered to as Page Flows.

The analyst

When you talk to an analyst, he/she might speak about business processes. A business process is relevant in a broader business context and might be long running.
In the example with the book order the business process starts after the order was commited by the web application. First the process checks whether the book is in stock. If not is re-ordered from the wholesaler. Then it checks whether the payment has been received and if yes the book is finally delivered to the customer.
Business processes are mainly decribed by specifications such as BPEL/BPNM, UML activity diagrams or XPDL for example used by the BEA Aqualogic BPM Suite.

The integrator

The story gets more complicated if one talks to a person who has to integrate different systems.
For this purpose an Enterprise Service Bus (ESB) is used in more and more projects.
One of the main responsibilities of an ESB is to virtualize the interaction amongst service providers and consumers.
This requires small processes as well, which are used for mediation. Mediation involves for instance schema and protocol transformations.
In our example the wholesaler might support a different message schema and transport protocol than the bookshop. The mediation is conducted by the ESB.
Currently no standardized notation is available to decribe Mediation Processes. Java Business Integration (JBI), which is for instance implemented by Apache ServiceMix, defines these processes implicit as part of the ServiceAssemblies.

processes (39k image)

What I experience is the following: If the discussion is about processes, often BPEL is suggested as the ultimate technical means. But if the focus is on page flow or mediation this might no be the right option.
Although the borders seem to blur. For instance JBoss Seam uses their jBPM engine to describe page flows as well.

Platform Independent BPEL Designer

For good reason a lot of people are claiming a contract first approach in terms of Web Service design.
I think it makes perfect sense to use a sound vendor independent format to describe important resources like for instance Web Service interfaces.
But this approach is not limited to WSDL only. It applies to Business Process Execution Language (BPEL) as well as business processes are very valuable resources for every company. So if you have to model bunsiness processes for technologies like Microsoft Biztalk Server 2004 or BEA Weblogic Integration you might be good advised to use a BPEL first approach. Two tools that might help you are: Oracle BPEL Designer and
Cape Clear Orchestrator Beta. Both are Eclipse plug-ins and create plain BPEL 1.1 which in turn can be imported to the application of your choice.