Business Process Orchestration and Choreography Modeling
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In our time of electronic message exchange over the internet between participants of a business process one question becomes more and more pressing: “How do I design a business process orchestration?”
This is the right question. The not so good question would be: “How do I design message exchange?”. Designing message exchange in itself is nothing wrong. And most probably this is the first question that is asked at the beginning. And it needs to be asked at the end as well. But at the core of it is the question, how the business process shall be orchestrated. The reason is, because the degree of freedom one has to orchestrate messages is predetermined by the business process orchestration.
It is a major difference, if there are two given systems that implement given business processes and they shall be connected by designing messages versus having the freedom to design the business process in itself to be loosely coupled to another business process that can as well be designed.
One approach to designing business process orchestration is modeling it top down. This possibility is offered with BPMN 2.0. This is done in at least two steps.
The first step is to step back for a moment and take the view of a global observer on the business process. This it what it means to design a choreography model, or in BPMN 2.0 terminology a Choreography.
A Choreography describes the sequence of interactions between participants as it is observed by a global observer. The global observer has an overview over all participants and interactions at the same time. However the observer does not influence the interactions. The message sequence is completely enforced by the participants. A Choreography task represents an interaction between two or more participants in the scope of the model.
So even if there is no global process implementation in the end, it makes sense to design a process top-down bay taking a birds-eye view.
In a second step this process needs to be broken down into the processes that are relevant for each participant – i.e. that each of the participants need to respectively can implement.
The compelling benefit of the method is the simplicity of the first design as is can be done by using the Choreography. Also it makes it easier to design the processes of the participants with reference to an already predefined design – the Choreography.
