1. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1 UML Activity Diagrams

2. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 2 Objectives  To read and write UML activity diagrams  To know when and how to use activity diagrams

3. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 3 Topics  Processes and process descriptions  Activity diagram notation  Activity diagram execution model  Making activity diagrams

4. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 4 Processes and Their Description Process description notations describe design processes as well as computational processes we design. A process is a collection of related tasks that transforms a set of inputs into a set of outputs. An activity diagram shows actions and the flow of control and data between them.

5. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 5 Activities and Actions An activity is a non-atomic task or procedure decomposable into actions. An action is a task or procedure that cannot be broken into parts. An activity is a non-atomic task or procedure decomposable into actions. An action is a task or procedure that cannot be broken into parts.

6. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 6 Activity Graph Elements activity symbol action node activity edge initial node activity final node

7. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 7 Branching Nodes guards merge node decision node

8. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 8 Deadlock RunDrier cannot execute: when the activity begins, there is a token on the edge from the initial node but not on the other incoming edge.

9. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 9 Forking and Joining Nodes fork node join node

10. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 10 Object Nodes Data and objects are shown as object nodes. object node object node state

11. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 11 Control and Data Flow Example control flow data flows

12. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 12 Activity Parameters  Activity parameters are object nodes placed on activity symbol boundaries to indicate data or object inputs or outputs.  Activity parameters contain the data or object name.  Activity parameter types are specified in the activity symbol beneath the activity name.

13. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 13 Activity Parameter Example output activity parameter input activity parameter activity parameter types

14. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 14 Activity Diagram Heuristics  Flow control and objects down the page and left to right.  Name activities and actions with verb phrases.  Name object nodes with noun phrases.  Don’t use both control and data flows when a data flow alone can do the job.  Make sure that all nodes entering an action node can provide tokens concurrently.  Use the [else] guard at every branch.

15. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 15 When to Use Activity Diagrams When making a dynamic model of any process. Design processes (what designers do) Designed processes (what designers create)  During analysis  During resolution

16. © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 16 Summary  A process is a collection of related tasks that transforms a set of inputs to a set of outputs.  UML activity diagrams model processes by depicting actions and the flow of control and data between them.  Activity symbols contain activity graphs consisting of action nodes action edges data nodes special nodes for starting and stopping activities, branching, forking, and joining  Activity diagrams can represent any process and are useful throughout software design.