BPMN Iteration and Loops: An Introduction (Enterprise Edition Only)

Business Process Model and Notation (BPMN) provides powerful constructs for modeling repetitive activities within business processes. Iteration and loops are essential for representing tasks or subprocesses that need to be executed multiple times under certain conditions. BPMN supports iteration through standard loops and multi-instance loops (iterations).

Loops and Iterations

1. Standard Looping:

  • Loop Characteristics: Tasks and subprocesses can be configured to repeat based on specific conditions using loop characteristics. This includes a loop condition (e.g., a condition that evaluates to true or false) and a maximum number of iterations.
  • Usage Example: A task to review a document may loop until the document meets quality standards or a maximum number of reviews is reached.

2. Multi-Instance Iterations:

  • Parallel and Sequential: Multi-instance loops allow tasks or subprocesses to be executed multiple times either in parallel or sequentially. Each instance can process different data elements from an input collection.
  • Parallel Instances: When tasks are performed simultaneously, enabling efficient handling of multiple items (e.g., sending emails to multiple recipients at once).
  • Sequential Instances: When tasks are executed one after another, useful for processes that require ordered execution (e.g., processing a list of orders one by one).

Key Components:

  • Input Collection: The list, array, or query result set that drives the number of instances to be created, one instance per entry.
  • Output Collection: The output result set created by the iteration or loop, one entry per instance.
  • Loop Characteristics: Configured within the task or subprocess properties to define loop behavior.
  • Completion Condition: Determines when the looping or iteration should stop, such as a condition being met or a counter reaching its limit.
  • Cardinality: In multi-instance loops, cardinality specifies the number of instances to be created.

Benefits:

  • Efficiency: Iteration and loops help in automating repetitive activities, improving process efficiency.
  • Clarity: Clear visual representation of repetitive tasks aids in understanding and analyzing business processes.
  • Flexibility: Supports both structured and unstructured process flows, catering to diverse business requirements.