Activity diagram
Transcription
Activity diagram
Activity diagram The Activity Diagram What is it ? graphical representation of process and control flow Purpose Describe business processes and individual use case scenarios Model concurrent behavior The Activity Diagram (contd.) Helpful for modeling workflow and use case scenarios without having to dive into OO technology. Very well understood without any computer knowledge, so are an excellent means for user communication They are also very good means to describe concurrent behavior in a process. The Activity Diagram Notation (1) A Sequence in an Activity Diagram Synchronization in an Activity Diagram Parallel Split in an Activity Diagram Exclusive Choice in an Activity Diagram Elements of an Activity Diagram Registration example Activity Start Browse Course Catalog Select Course Info Guard Confirm Registration Enter Personal Data Branch [data correct] End [else] Update Course Kropp, M. SWEED 2001 Send Email Print Bill Elements of an Activity Diagram Customer Browse Course Catalog Registration System Select Course Info Database System Billing System Swimlane [else] Enter Personal Data [data correct] Confirm Registration Fork Send Email Join Kropp, M. SWEED 2001 Update Course Print Bill Elements of An Activity Diagram (Contd.) The above diagram shows the sequence of steps with explicit modeling of parallel behavior represented by fork and join . fork has one incoming transition and several outgoing transitions. The outgoing transitions are all executed in parallel. join has several incoming transitions and only one outgoing transition. It is also called a synchronization, since the join specifies, that the outgoing transition is only executed when all incoming transitions have completed their activity. Swimlanes allow you to specify who is doing a specified action. For this you arrange your actions in vertical zones, each separated by dashed lines. When to Use Activity Diagrams There are actually two main strengths to activity diagrams: 1. They can be used very well for visualizing business and workflow processes. They are not yet SW related and can be easily understood by users and customers. 2. The support modeling parallel behavior. This again makes them a very good tool for workflow modeling. Hence, they can be used for : Analyzing Use Cases Understanding Workflows Describing complicated sequential algorithms Modeling parallel behavior Elements of Activity Diagrams Activity: a behavior that an object carries out while in a particular state Transition: a movement from one activity or state to another Branch: a diamond symbol containing a condition whose results provide transitions to different paths of activities Synchronization bar: horizontal or vertical bars denoting parallel or concurrent paths of activities Fork: the beginning of parallel activities Join: the end of parallel activities Swimlanes: columns representing different organizatonal units of the system branch activity synchronization bar swimlane