Kyung Hee University System Functional Model OOSD 담당조교 석사과정 이정환

Kyung Hee University Activity Diagrams  Contains information about the dynamics of these functions  In a static view of system functionality  Consider when one use case uses several others. You do not see in what order those other use cases are used  Consider when one use case extends another. You do not see under what conditions or at what point the extension occurs  Consider use cases that must be temporally ordered in a particular way. You do not see the required sequencing among them

Kyung Hee University Activity Diagrams (cont’d)  Provide one solution to these deficiencies, workflow view of activities  When the use case uses several other use cases, the diagram depicts the order in which they are used  When the use case is extended by another use case, the diagram shows when and why extension occurs

Kyung Hee University Activity Diagrams (cont’d)  Activity Diagram Notation  When modeling business processes, it can correspond to a human task, such as approving a document  When specifying temporal constraints among use cases, it can correspond to a system function (that is, to a use case)  When “flowcharting” a use case, it can correspond to one step in that use case

Kyung Hee University Activity Diagrams (cont’d)  Simple example  The simplest relationship between activities occurs when one must follow the other Figure 1. Activity Y follows activity X

Kyung Hee University Activity Diagrams (cont’d)  You can also indicate that one activity conditionally follows another

Kyung Hee University Activity Diagrams (cont’d) Figure 2. Activity Y conditionally follows activity X

Kyung Hee University Activity Diagrams (cont’d) Figure 3. Nested decision points

Kyung Hee University Activity Diagrams (cont’d)  In some cases, you might want to specify that activity X is followed by many possible instantiations (or invocations) of activity Y. Although it is not an official part of the UML

Kyung Hee University Activity Diagrams (cont’d) Figure 4. Activity X is followed by multiple activity Y’s

Kyung Hee University Activity Diagrams (cont’d)  Synchronization bars  UML activity diagram may specify parallelism  When multiple activities immediately follow a synchronization bar (as Y1 and Y2 follow the leftmost bar in the top half of Figure 5), those activities may occur in parallel  When multiple activities immediately precede a synchronization bar (as Y1 and Y2 precede the rightmost bar), they must all be completed before execution continues beyond that bar

Kyung Hee University Activity Diagrams (cont’d) Figure 5. Parallel activities

Kyung Hee University Activity Diagrams (cont’d)  An activity diagram for placing an order  Recall the business use case diagram from last week : Place Order, Cancel Order, Cancel Order Item, and Return Order Item  First consider placing an order. This use case consists of at least four distinct activities  Entering the order, which involves taking information about the order and the payment method from the customer  Authorizing the purchase, which requires verification that the required funds can be obtained from the customer using the specified payment method  Allocation the order items from inventory  Shipping the order

Kyung Hee University Activity Diagrams (cont’d) Figure 6. A first activity diagram for placing an order

Kyung Hee University Activity Diagrams (cont’d)  The activity diagram is a refinement of the use case  UML defines the following refinement stereotypes  > indicates a design (or development) refinement. During the development process, detail has been added to something. The two features represent the same concept at differing levels of detail  > indicates any other kind of refinement, such as the refinement of an obvious design into a less obvious, but more efficient, one

Kyung Hee University Activity Diagrams (cont’d)  Draw the activity diagram for  “Cancel Order Item”  “Cancel Order”  “Return Order”