BPMN Gateways Simplified

Here’s a simple mantra for understanding and using gateways in BPMN 2.0.

If you want to instantiate a process, use an Event-based Gateway; if you want to fork and merge flows, use the Parallel Gateway. If you want exactly one path to be chosen, use the XOR Gateway; if one or more paths can follow, use the Inclusive Gateway. If several factors, rules, and analyses can influence the decision, with only one outgoing path, use the Complex Gateway.

Explanations:

• Event-Based Gateway: This is used when the flow depends on a specific event or condition being met (receiving a message, a timer event). It can be exclusive or parallel.
• Parallel Gateway: Use this gateway when you want to fork the process into multiple parallel paths (execute multiple paths simultaneously) or merge them later (wait for all parallel paths to complete). To re-iterate, all paths are executed simultaneously when forking, and the process waits for all parallel paths to complete before moving on when merging.
• XOR Gateway: Use XOR when only one of the outgoing paths should be taken, based on a decision or condition. This is also the most commonly used gateway.
• Inclusive Gateway: Use this symbol when one or more paths could be chosen, depending on conditions. Unlike XOR, which only allows one path, it lets you select multiple paths if their conditions are true.
• Complex Gateway: Use this gateway when the decision-making process is too complex to be represented simply by XOR or Inclusive gateways. It allows for more intricate conditions or logic that involve several factors and rules. I would recommend avoiding this gateway to the extent possible, instead decompose the flow to make it simple.

I recommend doing further research, this is a “just enough” explainer to get you started!