Creating activity diagrams

In UML modeling, you can use activity diagrams to model the sequence of actions that must occur in a system or application, or to describe what happens in a business process workflow.

About this task

When you create an activity diagram, you can add and modify activity nodes and edges, and organize them using partitions. You can also select a group of activity nodes and move them to another activity in your model.

In the business process modeling domain, activity diagrams describe the workflow of a business use case. In the system modeling domain, they show the structure of the flow of events in a system use case. Using activity nodes and edges to represent the flow of control and data between the objects in the use case, you can create one or several activity diagrams to illustrate how the activity nodes, activity edges, and other activity diagram model elements relate to each other.

Before UML 2.0, activity diagrams were part of state machines and were referred to as activity graphs. Since UML 2.0 the activity diagram is a distinct diagram, separate from a state machine, that focuses on the tasks that are performed.

Adding call behaviors to activity diagrams
When you model the flow of control in an activity diagram, you can define how a specific behavior is invoked by adding a call behavior node. You can create a reference to behavior in a new activity, state machine, or interaction diagram, create a reference to behavior in an existing diagram, or reference a behavior that is not currently specified in the model.
Adding call operations to activity diagrams
When you model the flow of objects in an activity diagram, you can add call operations, which are actions that invoke operations in a model. You can create a reference to a new operation or to an existing operation. The referenced operation defines a type of behavior, such as a transformation or query, and the target operation runs that object transformation or query.
Removing default names from call behavior actions and call operation actions
You can remove the default names from existing call behavior actions or call operation actions. In previous versions of the product, the actions for call operations and call behaviors were assigned default names. You can now specify a name or leave the action name unspecified, in which case the action's referenced behavior or operation is displayed.
Adding variables to activities
When you use activities to model the flow of information, you can add variables that specify the data that actions in a group share. Typically, you use variables to store and access information within or between actions. An application might use variables to store or access information as a complement or alternative to using object flows. You modify variables by using variable actions.
Adding variable actions to activity diagrams
When you use activity diagrams to model the flow of information, you can create actions that define variables and their data. You can use variable actions to add, read, or remove variable values, as well as to clear all values from the variable values list. You can use variable actions as an alternative or a complement to modeling with object flows, and they are not subject to control flows or other object-related constraints.
Describing complex activities in structured activity nodes
In activity diagrams, when you need to describe a complex activity in a structured activity node, you can create a subdiagram that focuses on the contents of the structured activity node.
Grouping behaviors in activity diagrams
You can group the activity nodes and edges in an activity diagram using partitions, so that each partition models a part of the activity. Depending on the workflow or process that you are modeling, you can create one or several partitions and specify how you want them displayed in activity diagrams. The activity nodes and edges can reference one or several partitions in an activity diagram.
Adding call behaviors to activity diagrams
When you model the flow of control in an activity diagram, you can define how a specific behavior is invoked by adding a call behavior node. You can create a reference to behavior in a new activity, state machine, or interaction diagram, create a reference to behavior in an existing diagram, or reference a behavior that is not currently specified in the model.
Adding call operations to activity diagrams
When you model the flow of objects in an activity diagram, you can add call operations, which are actions that invoke operations in a model. You can create a reference to a new operation or to an existing operation. The referenced operation defines a type of behavior, such as a transformation or query, and the target operation runs that object transformation or query.
Removing default names from call behavior actions and call operation actions
You can remove the default names from existing call behavior actions or call operation actions. In previous versions of the product, the actions for call operations and call behaviors were assigned default names. You can now specify a name or leave the action name unspecified, in which case the action's referenced behavior or operation is displayed.
Adding variables to activities
When you use activities to model the flow of information, you can add variables that specify the data that actions in a group share. Typically, you use variables to store and access information within or between actions. An application might use variables to store or access information as a complement or alternative to using object flows. You modify variables by using variable actions.
Adding variable actions to activity diagrams
When you use activity diagrams to model the flow of information, you can create actions that define variables and their data. You can use variable actions to add, read, or remove variable values, as well as to clear all values from the variable values list. You can use variable actions as an alternative or a complement to modeling with object flows, and they are not subject to control flows or other object-related constraints.
Describing complex activities in structured activity nodes
In activity diagrams, when you need to describe a complex activity in a structured activity node, you can create a subdiagram that focuses on the contents of the structured activity node.
Grouping behaviors in activity diagrams
You can group the activity nodes and edges in an activity diagram using partitions, so that each partition models a part of the activity. Depending on the workflow or process that you are modeling, you can create one or several partitions and specify how you want them displayed in activity diagrams. The activity nodes and edges can reference one or several partitions in an activity diagram.

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