What is a Complex Gateway in BPMN?

A Complex Gateway enables custom routing logic that standard gateways cannot express. It uses expressions to define arbitrary split and join behavior, such as quorum-based decisions.

When should I use a Complex Gateway?

Use Complex Gateways when you need M-of-N synchronization, custom join conditions, or logic that does not fit AND/OR/XOR patterns. Use standard gateways when possible for clarity.

How is the Complex Gateway different from related elements?

Complex Gateways allow arbitrary logic via expressions. Parallel requires all; Inclusive requires activated paths; Exclusive requires one. Complex is for scenarios none of these can model.

gateways

Complex Gateway

A Complex Gateway provides custom routing logic that cannot be expressed by other gateway types. It uses expressions to define arbitrary split and join behavior.

What is a Complex Gateway?

A Complex Gateway handles routing scenarios too complex for standard gateways. It allows modelers to define custom split and join logic using expressions when standard AND/OR/XOR semantics do not fit.

Visual Representation

A Complex Gateway displays as a diamond shape containing an asterisk (*). The asterisk represents the custom/complex nature of its routing logic.

Key Characteristics

Custom logic: Defines routing using expressions or scripts
Flexible join rules: Can specify partial synchronization (e.g., 2 of 3 paths)
M of N patterns: Useful for quorum-based decisions
Last resort: Use only when other gateway types cannot model the scenario

Common mistake

Using a Complex Gateway when a simpler gateway type would work. Complex Gateways make diagrams harder to understand and are rarely supported by engines. Always try Exclusive, Parallel, or Inclusive first.