A UML Interaction Overview Diagram visualizes control flow by orchestrating other Interaction diagrams. It is a variant of the Activity Diagram, so common flow nodes—Start/End, Decision/Merge, and Fork/Join—behave the same. What changes is the content of the steps: instead of activity actions, you place two rectangular elements.
Use this diagram when you want a compact, flow‑first summary that ties multiple detailed scenarios together. In Sparx Systems Enterprise Architect, elements and connectors are available on the Interaction Overview pages of the Diagram Toolbox.
Interaction Overview diagrams help when you need a flow‑first summary that stitches together detailed scenarios. They reuse existing interactions, show branches and concurrency clearly, and keep large behaviors readable.
Summarize end‑to‑end behavior by chaining Sequence, Communication, Timing, or nested Interaction Overview diagrams. Stakeholders see the path at a glance.
Reference, don’t copy. An Interaction Occurrence points to an existing diagram, so updates to the original flow are reflected in the overview—less rework, consistent results.
Use familiar Decision/Merge and Fork/Join nodes (from Activity diagrams) to present alternatives and parallel subflows without redrawing messages.
Long message exchanges collapse into labeled frames, turning sprawling sequences into a page that fits design reviews and sign‑offs.
In Sparx Systems Enterprise Architect, each Interaction or Interaction Occurrence frame can open the referenced diagram for detail. This keeps the overview navigable while preserving traceability.
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| UML Element Type | Icon in EA Toolbox | Description |
|---|---|---|
| Diagram Frame |
|
A frame that references an Interaction diagram, used to place a scenario in context within the overview. |
| Interaction Occurrence |
|
A reference to an existing Interaction diagram, drawn as a frame with ref in the header and the diagram name inside. Used inline as an invocation of that interaction. |
| Control Flow |
|
A connector between nodes that models the progression of control from one step to the next. |
| UML Connector Type | Icon in EA Toolbox | Description |
|---|---|---|
| Initial |
|
Marks the entry point of the flow when the activity (overview) starts. |
| Decision |
|
A branching point with guard conditions; flow continues on the path whose condition evaluates to true. |
| Merge |
|
Joins alternative paths back into a single flow. |
| Fork/Join |
|
Splits one incoming flow into multiple concurrent flows, joins multiple flows into one, or performs both in a single node. |
| Flow Final |
|
Terminates a single path of execution without ending the entire activity. |
| Final |
|
Indicates the completion of the activity; reaching it stops all remaining execution. |
This UML Interaction Overview Diagram shows a compact, flow‑first view of a checkout. An Initial node (labeled Request Item) starts the control flow. The first Interaction Occurrence (ref) frame SearchForItem represents a reused interaction (an interaction use in UML terms). A Decision node Item Exists? splits the path:
After the basket step, a second Decision Sale Finalized? branches:
This interaction overview diagram UML example emphasizes orchestration over message detail: reusable Interaction Occurrence frames summarize Sequence/Communication scenarios, while Control Flows, Decision/Merge, Final, and Flow Final nodes keep the logic readable. In Sparx Systems Enterprise Architect, this pattern lets reviewers drill down into each ref frame while keeping the end‑to‑end path on a single page—ideal when contrasting alternatives or presenting a interaction overview diagram vs activity diagram discussion.
Use these essential steps:
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