Signals represent how activities can be modified from outside the system. Merge EventĪ merge event brings together multiple flows that are not concurrent. This refers to an event that stops the flow for a time an hourglass depicts it. It is represented as a straight, slightly thicker line in an activity diagram.Ī join node joins multiple concurrent flows back into a single outgoing flow.Ī fork and join mode used together are often referred to as synchronization. SynchronizationĪ fork node is used to split a single incoming flow into multiple concurrent flows. These are not essential, but are useful when a specific answer, such as "Yes, three labels are printed," is needed before moving forward. In UML, guards are a statement written next to a decision diamond that must be true before moving next to the next activity. You can also label one of the paths "else." Guards
The outgoing alternates should be labeled with a condition or guard expression. When an activity requires a decision prior to moving on to the next activity, add a diamond between the two activities. Decisions and BranchingĪ diamond represents a decision with alternate paths. An object flow arrow from an object to an action indicates that the action state uses the object. An object flow arrow from an action to an object means that the action creates or influences the object. Object flow refers to the creation and modification of objects by activities. They are usually drawn with an arrowed line. Action FlowĪction flows, also called edges and paths, illustrate the transitions from one action state to another. You can draw an action state in SmartDraw using a rectangle with rounded corners. Activity or Action StateĪn action state represents the non-interruptible action of objects.
For activity diagram using swimlanes, make sure the start point is placed in the top left corner of the first column. Learn about activity diagram symbols below:īasic Activity Diagram Notations and Symbols Initial State or Start PointĪ small filled circle followed by an arrow represents the initial action state or the start point for any activity diagram. In between there are ways to depict activities, flows, decisions, guards, merge and time events and more.