Activity Diagram Flashcards
(16 cards)
What is the primary focus of an activity diagram?
Modelling procedural processing
Node
actions, objects, control nodes
Edges
control flow, object flow
What is a “token” in activity diagrams?
A virtual mechanism that:
- grants execution permission to actions (control token)
- transports data (object token)
What are the 4 key control nodes?
- Initial node: Starts activity
- Activity final node: Ends all flows
- Decision node: Splits paths with guards
- Merge node: Combines alternative paths
How are concurrent paths modeled?
- Parallelisation node: Splits into concurrent flows
- Synchronisation node: Waits for all flows to complete
What is an object node?
Represents data/objects exchanged between actions
Central Buffers vs Data Stores
- Central Buffer: Transient (deletes tokens after reading)
- Data Store: Permanent (copies tokens)
What are the 2 types of event-based actions?
- Send signal: Triggers an event
- Accept event: Waits for an event/time
What is a partition?
Groups nodes by responsibility/roles
How are exception handled?
- Exception handler: Replaces a failed action
- Interruptible region: Terminates a group of actions on an event
What symbol represents a call behaviour action?
Fork icon
What happens when a token reaches an activity final node?
All flows terminate immediately (even concurrent ones)
How are guards written in activity diagrams?
In square brackets: [grade >= 5]. Must be mutually exclusive for decision nodes.
What does {weight=30} on an edge mean?
The action requires 30 tokens to execute (default=1)
When are connectors used?
To simplify diagrams when actions are far apart (avoid crossing lines)
