Information Systems Engineering Activity Diagram 1

Activity diagrams illustrate the flow of functionality in a system It used in requirements gathering to illustrate the flow of events through a use case These diagrams define where the workflow starts, where it ends, what activities occur during the workflow, and in what order the activities occur An activity is a task that is performed during the workflow 2

Elements of Activity Diagram NotationRepresentationElement End State Start State Activity Show where the flow begins. Each activity diagram must have one and only one start state Show where the flow ends. You can have more than one end state on the diagram (Optional) A step in the process Select Flight 3

Elements of Activity Diagram cont. NotationRepresentationElement Object Flows Objects Transitions An entity that is used or changed by an activity in the flow. You can understand where and how the object's state changes. Link objects to activities. from an activity to the object it changes, or from the object to the activity that needs to use it (as input). shows how the flow of control moves from one activity to another Object Name [State] 4

Elements of Activity Diagram cont. NotationRepresentationElement Synchronization Decision points A way to show that two or more branches of a flow occur in parallel. It can be either horizontal or vertical Shows decision point in the work flow 5

Reserve Seat [Invalid account, credit system not available ] Ticket Enter Credit Information [Approved] Generate Confirmation Number [Purchased] Ticket [Unconfirmed] 6

Activity: Actions A detailed steps can be added to the activity by using actions. Actions are smaller steps that take place within an activity They may occur at one of four times: Upon entering the activity. An entry action occurs as soon as the activity begins - "entry“ When exiting the activity. An exit action occurs as you are leaving the activity - "exit“ While performing the activity. These actions occur while in the activity and continue until you leave the activity - do“ Upon a specific event. These actions happen if and only if a specific event occurs - "event” followed by the event name Elements of Activity Diagram 7

Activity: Actions cont. Elements of Activity Diagram Display Available Flights entry/ Find all flights for selected cities entry/ Determine flights with available seats do/ Display list of flights with available seats event/ User request cost information/ Display cost information 8

Source Mastering UML with Rational Rose 2002 Transitions: Limitations Event: The event must happen in order for the transition to occur The transition arrow is labeled with the event name, along with any arguments in parenthesis Elements of Activity Diagram Reserve seat Cancel reservation Refund credit purchase Cancel

Source Mastering UML with Rational Rose 2002 Transitions: Limitations cont. Guard condition: While an event triggers a transition, a guard condition controls whether or not the transition can occur If a guard condition is present, it must be true in order for the transition to occur The guard condition is listed along the transition arrow, following any event, and is enclosed in square brackets Elements of Activity Diagram Reserve seat Generate Confirmation Number [New reservation]

Synchronization & Decision Point Example Elements of Activity Diagram Reserve seatGenerate Confirmation Number [Invalid account, credit system not available ] Generate Enter Credit Information [Approved] Display Confirmation Number 11

Draw a detailed activity diagram for the rent a video item use case. 1.Clerk scans card 2.Clerk scans desired video(s) 3.Terminal displays details of each video scanned 4.Verify customer(not a customer, unreliable, customer found) 5.Terminal displays price and due date 6.Terminal prints receipt for signature Example 12

Example 13

Draw a use case diagram for a Bank system The following use cases are defined: Open customer account Deposit funds Transfer funds Withdraw money Order bank statment View account history Change PIN Draw a detailed activity diagram for the Open customer account and Withdraw money use cases. Practice 14

Use case Diagram: Bank system 15

Activity Diagram: Open customer account 16

Activity Diagram: Withdraw money 17