Activity diagram

An activity diagram is a UML diagram that shows the steps or tasks in a process. An activity diagram is very similar to a flowchart because it provides a view of the flow between activities in a process. Activity diagrams are similar to statechart diagrams because both diagrams model the dynamic parts of a system and they both belong to a state machine. Activity diagrams typically show how activities interact with each other; whereas statechart diagrams model the discrete stages of an object's lifetime.

Activities represent the performance of a task or duty in a workflow; transitions provide the pathway between each activity. Activity diagrams often show parallel activities and alternate flow.

When you model a process with an activity diagram, you use initial and final states to mark the beginning and end of a workflow, and decisions to represent the specific location where a workflow may branch or merge based upon a guard condition. Many activities involve simultaneous workflow, and you can use multiple synchronizations to visually define forks and joins. Swimlanes can be used to group a set of activities based on roles or responsibilities.

Activity diagrams are helpful because they map out workflow and identify the most important activities that occur in a process. You normally develop activity diagrams in all phases of a software project. Possible uses of activity diagrams include the following:

• Before starting the software project, you can create activity diagrams to model the most important workflows in the business. This will help you define the structure and dynamics of the business.

• During the requirements phase, you can create activity diagrams to further break down and visualize the flow of events in use cases.

• During analysis and design, you can use activity diagrams to help define the behavior of operations.

• Working with Activity Diagrams
• Activities
• Final States
• Initial States
• Inserting Actions
• Transitions
• Working with State Machine (Activity and Statechart) Diagrams

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