I define control flow as the order in which a set of process steps executes. In other words, I focus on the sequence of activities and events in a process. For example, I state that Activity A happens before Activity B. Therefore, I model strict sequences, branches, and synchronization. Moreover, I use control flow to show when one step triggers the next. Consequently, I can detect gaps and timing issues early.
I learned about control flow from flowcharts. First, engineers used boxes and arrows to show program logic. Then, analysts shifted to data flow diagrams. However, with UML activity diagrams and BPMN process diagrams, I returned to this kind of thinking. Thus, I often combine ideas from both traditions.
I use BPMN diagrams to visualize control flow. In BPMN, I model start events, tasks, gateways, sequence flows, and end events. For example, I draw a sequence flow when one task follows another. In addition, I use gateways to show alternative paths. Meanwhile, I model parallelism with parallel gateways and synchronization with joins. As a result, stakeholders can understand sequences and parallel work steps easily.
I contrast control flow with data flow frequently. In data flow diagrams, I show who produces what data and who needs it. In contrast, the process flow shows who acts when in the process. Therefore, data flow emphasizes inputs and outputs. Conversely, it emphasizes processing logic and timing. However, I never treat them as mutually exclusive. Instead, I use both views to get a full picture.
I apply control flow when sequence matters. For instance, I model user interactions, transaction steps, and safety procedures with it. Moreover, I choose control flow for linear business processes and workflows. Likewise, I choose it when gateway decisions determine alternate paths. Furthermore, I use it to model concurrent tasks that may run at the same time.
I keep my control flow models simple. First, I name each activity clearly. Next, I show transitions with sequence flows. Then, I add gateway conditions to explain choices. After that, I model synchronization points for parallel paths. Finally, I mark the end conditions with explicit end events.
I gain several benefits from clear control flow models. For example, I create precise test cases and process validations. In addition, I reveal timing and synchronization issues. Consequently, I reduce integration risks. Furthermore, I improve communication between developers, analysts, and business stakeholders. Hence, teams implement process-supported features more reliably.
I watch for common pitfalls. For instance, I avoid mixing data dependencies into the control flow without clear labels. Also, I avoid overcomplicating diagrams with too many gateways. Instead, I break complex processes into smaller subprocesses. This approach helps readability and later translation.
I recommend that requirements engineers learn both control flow and data flow thinking. First, study flowcharts, UML activity diagrams, and BPMN. Second, practice drawing data flow diagrams. Third, compare the two views for the same process scenario. In this way, I gain better specification skills. Moreover, I deliver clearer requirements and fewer misunderstandings. Therefore, I consider it an essential tool in my requirements toolbox.