A perspective from Business and IT on Process Modelling and Execution - BPMN and BPEL
Process Modelling in the business domain varies considerably from modelling in the IT domain. The concept of describing a process in terms of the business objectives is perhaps the primary difference between the two domains. In the IT domain the importance of executable rules takes precedence over the possibilities, interactions and interpretations offered by some of the modelling principles. In the business domain, Business Process Modelling Notation (BPMN) is a well-known standard, used as a graphical notation that defines the steps in a business process.
BPMN is widely accepted as providing the standard set of diagramming conventions for describing business processes and more recently as a basis for actual execution by some BPM execution engines.
BPMN is a core enabler of BPM and an important tool that empowers business users to design and implement real solutions on a BPMS. The primary goal of BPMN is to provide a business process modelling notation that is understandable by all business users, Business Analyst, System Analyst, Technical Developers and Business managers. For a quick explanatory guide on the elements of BPMN refer to the Object Management Group website at http://www.bpmn.org/
A common use of BPMN is to enable the business oriented visualisation of XML languages (such as BPEL, Business Process Execution Language) designed for the execution of business processes. BPMN takes a process-oriented approach to process modelling, that is more conducive to the way business analysts model. BPMN is intended to supply sufficient information to allow it to be the source definition of an executable process.
Business Process Execution Language (BPEL) is an XML-based system to system business process orchestration language that uses web services. The key objective of BPEL is to standardise the format of business process flow definition so that processes involving multiple technology solutions and interfaces can be orchestrated together to deliver business solutions.
In my view BPMN and BPEL are not competing technologies or modelling notations and in most organisations co-exist to enable the definition and execution of processes from both a business and technology perspective. The use of BPEL has been fruitful for a number of years in IT, particularly in relation to service orchestration and the development of SOA and SOI.
Therefore BPEL is more commonly used in the IT domain where the focus is process execution and tends to be more concerned with interaction between existing IT systems, data transformation and messaging. BPMN is almost exclusively used in the business domain to describe business processes in as much detail as possible to allow definition of human interactions, events, triggers, business rules, content, metadata, actors, roles and hand-off points.