Business Process Management Notation (BPMN) is a process diagramming method that is relatively new to me, but I find it very useful. I first saw it about two years ago on a consulting contract in Finland where there were process improvement professionals from around the European Union. They told me that the BPMN method was quite common in the EU. As any of us improvement folks would do, I decided to look into it and found it to be a good method.
Similarities to traditional flow charting
BPMN uses symbols similar to those that a traditional six sigma person will recognize: rectangles for activities (although they are rounded), diamond shapes for decision steps, and arrows for sequencing. Swim-lanes are used, and sub-processes are allowed. That is about where the similarities end.
Differences between BPMN and traditional flow charting
There is a true standards guide to BPMN modeling that is managed by the Object Management Group (OMG) and is written and approved by BPM vendors and process modelers from all over the world. This guide is very detailed and provides standard symbols and methods to diagram and model processes. BPMN does not allow the freedom for the creator to adjust the format to fit a special case or to have a local standard. An example of a creator change would be the use of a stop-sign symbol at the end of a process, which is what the Bechtel LSS practitioners were taught when I worked there.
There are also defined rules for diamonds on how the flow splits on a decision. In this case the prior activity must be the action to determine the decision, and the diamond indicates the flow changes, based on the decision. This is a minor issue, but it is important for the modeling functions. Another difference is in the convention for parallel flows and the joining of parallel flows. There are distinct symbols for the creation and joining of parallel flows. The joining steps have a requirement that all the parallel flows arrive there before the flow will continue. This combination action was not clearly defined in traditional charting, where the creator might just route all flows into the same activity, and then assume it would wait there.
BPMN Message and communication flows
In BPMN, the communication between the process and an external organization, such as the customer, has a defined convention. If you look in the example at the beginning of this blog, you will see the customer swim-lane at the bottom, separated from the process. This convention is used because the process users do not generally have insight into the external organization processes. In BPMN you would typically leave the customer swim-lane empty and just connect the process diagram to the customer swim-lane with a dotted line to show the communication action.
There are also dotted line connection to data systems to show information being passed, as shown in the example, along with extra flow paths created with dotted lines that show information being passed between activities in the diagram, although this is not shown in the example.
My favorite convention in BPMN, which could be adopted into traditional charting, is the curved corner flow lines. This convention makes it clear in what direction things flow. The traditional form of squared corners made it slightly ambiguous where flows combined as to the direction of flow.
Activities and sub-process activities
Sub-processes can be described in a drill down graphic as we may do for traditional flow charting, but they can also be drawn in the primary diagram with a large activity-shaped rounded rectangle around the sub-process. There is also a convention in sub-processes that they may have multiple starts and ends. In fact, it is odd if a BPMN diagram has a single end or stop symbol because the convention is that a single end or stop symbol is created for every different condition that the process or sub-process ends. Therefore, most BPMN diagrams have multiple stop symbols.
Dynamic symbol shapes
There are standard symbol changes based on how they are used. A start symbol, which is some form of a circle, will have a thin line outer circle. It may have different symbols placed in the middle of the circle based on the trigger for the start activity. If there is a triggering event in the middle of a BPMN diagram, such as you might have for an error or mistake being detected, it uses a circle with a double line (looks like two concentric circles). When a BPMN process ends, it is indicated with a thick-lined circle. Both the intermediate and end symbols may also have inner symbols to indicate how they stop or are triggered. Here are a few examples:
Should Lean Six Sigma Practitioners learn this?
Yes, they should. I find this to be a much clearer way to diagram processes. What I have not discussed is probably the bigger reason to learn it: the diagrams have a standardized XML output format that will allow the diagram to be uploaded into nearly all BPMN software packages that allow a full process simulation of the direct creation of an automated process flow.
So yes. Go learn it.