Tool Mentor: Detailing a Use Case
Purpose
This tool mentor describes how to represent activity diagrams under a business use case in Rational Rose®.
Related Rational Unified Process activity: Detail a Use-Case
Overview
The following is a summary of the steps you perform to create an activity diagram in a use-case model:
- Create and describe an activity state in the diagram
- Connect activity states with transitions
- Create synchronization bars
- Create decisions with guard conditions
For detailed information about Activity Diagrams, see:
-
How
to > Work with Activity Diagrams in the Rational Rose
online help
Chapter
8, State Machine Diagrams and Specifications in the Using
Rose manual.
1. Create
an Activity Diagram in a Use Case 
Activity diagrams can be very effective in illustrating the workflow of various events in a use-case diagram. The flow of events of a use case describes what needs to be done by the system in order to provide value to an actor. Also, use case diagrams present a high level view of how the system is used as viewed from an outsider’s (actor’s) perspective. You can use activity diagrams to specify and define each event in a use case diagram.
For
complete details on how to create an activity diagram, see the Creating
an Activity Diagram topic in the Rational Rose online help.
2. Create
and Describe an Activity State in the Diagram
An activity represents the performance of a task or duty in a workflow. It may also represent the execution of a statement in a procedure. An activity is similar to a state, but expresses the intent that there is no significant waiting (for events) in an activity.
For
more information on activities, see the Activity
topic in the Rational Rose online help.
3. Connect
Activity States with Transitions
Transitions connect activities with other model elements. You can create a transition between two activities or between an activity and a state.
For
more information on transitions, see the
State Transition topic in the Rational Rose online help.
4. Create Synchronization
Bars
Synchronizations enable you to see a simultaneous workflow in an activity diagram. Synchronizations visually define forks and joins representing parallel workflow.
A fork construct is used to model a single flow of control that divides into two or more separate, but simultaneous flows. Every fork that appears on an activity diagram should ideally be accompanied by a corresponding join. A join consists of two of more flows of control that unite into a single flow of control. All model elements (such as activities) that appear between a fork and join must complete before the flow of controls can unite into one.
For
more information on synchronization bars, see the Synchronizations
topic in the Rational Rose online help.
5. Create
Decisions with Guard Conditions
A decision represents a specific location on an activity diagram where the workflow may branch based upon guard conditions. There may be more than two outgoing transitions with different guard conditions, but for the most part, a decision will have only two outgoing transitions determined by a Boolean expression.You can place guard conditions on transitions to or from almost any element on an activity diagram.
For
more information on decisions and guard conditions, see the Decisions
topic in the Rational Rose online help.
