What Is an Activity Diagram?

This section describes the UML Activity Diagram, which presents behaviors of a system by showing execution sequences of activities of the system.

What Is an Activity Diagram? An Activity Diagram is a diagram that describes internal behaviors of a single activity by showing execution sequences of actions that are needed to complete the activity.

In the OMG UML 2.4.1 specification, Activity Diagram is referred as: Activity modeling emphasizes the sequence and conditions for coordinating lower-level behaviors, rather than which classifiers own those behaviors. These are commonly called control flow and object flow models. The actions coordinated by activity models can be initiated because other actions finish executing, because objects and data become available, or because events occur external to the flow.

The picture below shows you a good example of an Activity Diagram describing internal behaviors of an activity called Process Order with sequenced actions:
UML Diagram Example - Activity Diagram

Last update: 2014.

Table of Contents

 About This UML Tutorial Book

 Introduction of UML (Unified Model Language)

 UML Class Diagram and Notations

UML Activity Diagram and Notations

What Is an Activity Diagram?

 Activity Diagram - Action Notation

 Activity Diagram - Control Flow Notation

 Activity Diagram - Start and Final Notations

 Activity Diagram - Decision Notation

 Activity Diagram - Merge Notation

 Activity Diagram - Fork Notation

 Activity Diagram - Join Notation

 Activity Diagram - Object Notation

 Activity Diagram - Send Signal Notation

 Activity Diagram - Accept Event Notation

 Activity Diagram - Partition (Swimlane) Notation

 Activity Diagram - Frame Notation and Parameters

 UML Sequence Diagram and Notations

 UML State Machine Diagram and Notations

 UML Use Case Diagram and Notations

 MS Visio 2010 - UML Drawing Tool

 References

 PDF Printing Version