Activity Diagram Symbols

Activity diagrams use a variety of symbols to represent different elements within a business process. Understanding these symbols is essential for interpreting and creating activity diagrams.

Key Symbols

• Activity/Action:

  • Represented by rounded rectangles.
  • Indicates a specific task or action performed within the process.

• Start Node:

  • Represented by a solid black circle.
  • Marks the beginning of the process.

• End Node:

  • Represented by a black circle surrounded by another circle.
  • Marks the completion of the process.

• Decision Node:

  • Represented by a diamond.
  • Indicates a branching point where a decision needs to be made.
  • Multiple outgoing arrows represent different possible outcomes.

• Merge Node:

  • Represented by a diamond.
  • Combines multiple paths into one, resuming the flow after a decision.

• Fork Node:

  • Represented by a thick horizontal or vertical bar with one incoming arrow and multiple outgoing arrows.
  • Indicates that parallel activities can begin.

• Join Node:

  • Represented by a thick horizontal or vertical bar with multiple incoming arrows and one outgoing arrow.
  • Combines multiple parallel activities back into a single flow.

• Transition/Flow:

  • Represented by arrows.
  • Indicates the movement from one activity or decision point to another.

• Swimlanes:

  • Represented by vertical or horizontal lanes that divide the diagram.
  • Used to assign activities to different actors or departments.

Graphical Representation

Activity Diagram Symbols

These symbols allow for the clear and structured representation of business processes, making activity diagrams easy to interpret.