Process flows should not be mapping the system. As you stated the system is not sequential. However people doing their jobs are sequential. Business Process modeling is an excellent adjunct to data flow. It can be decomposed very nicely to very atomic units and addresses the users point of view. However, too many people try to adopt just one model. Business process modeling is not sufficient and data flow diagrams serve a critical view of the system.
We are analyzing a loan system right now where we are making heavy use of business process (process flow) diagrams and data flow diagrams. Both views are critical to understanding the system.
Each process in the data flow IS a step from the process flows.
Anthony:
Analysis in the small is sequential. Analysis at high leves of abstraction is not.
I am reading a popular book on BPMN in which the author (well know in the BPMN communities) says the technique allows for unlimited decompostion. This is wrong. No one is going to start out at the more detail level (i.e., where there is definite start and stop points and process is sequential) and drill down to ever and ever greater levels of detail. Impling such is silly.
This is how deep (many level) decomposition procedes: The BA starts out at the big picture level. At this high level of abstraction there is no sequence nor start/stop points. He/she then decomposes downward to the more detail level where he/she then switches to sequence based flow charts.
So yes, DFD's and sequence based modeling techniques are needed. But sequence is non-applicable for higher levels of abstraction.
Tony
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