Tool Mentor: Designing Use Cases Using Rational XDE Developer - Java Platform Edition

Purpose

This section provides links to additional information related to this tool mentor.

• Use-Case Design

The steps in this tool mentor match those in the activity. Links to topics in Rational XDE™ online Help are marked with .

Overview

The following steps are performed in this tool mentor:

• [Describe Interactions Between Design Objects](#Describe Interactions Between Design Objects)
• [Simplify Sequence Diagrams Using Subsystems](#Simplify Sequence Diagrams Using Subsystems (optional)) (optional)
• [Describe Persistence-Related Behavior](#Describe Persistence-Related Behavior)
• [Refine the Flow of Events Description](#Refine the Flow of Events Description)
• [Unify Design Classes and Subsystems](#Unify Classes and Subsystems)
• [Evaluate the Results](#Evaluate Your Results)

Describe Interactions Between Design Objects

For each use-case realization, you should illustrate the interactions between its participating design objects by creating one or more sequence diagrams. You might have created early versions of these diagrams, the analysis use-case realizations, during Activity: Use-Case Analysis. These analysis use-case realizations describe interactions between analysis classes. They must be evolved to describe interactions between design elements.

One approach is to create a new use-case realization and sequence diagrams by following these steps:

1. Navigate to the Design-Model package in which the new use-case realizations are to be created. See Rational XDE Model Structure Guidelines.
2. Create a use-case diagram. See .
3. Add the use-case realization (a collaboration instance) to the diagram. (See .) Give it the same name as the use case.
4. Drag and drop the use case that it realizes onto the diagram. See .
5. Add a realization relationship from the use-case realization to the use case. See .
6. For each independent sub-flow (scenario) create one or more interaction instances. (In the Model Explorer, right-click the collaboration instance, and then click Add UML > Interaction Instance.) Consider naming the interaction instance “<use-case name> - <flow type>.”
7. Create a sequence diagram for this interaction instance. See .
8. Type a brief description of the scenario that the sequence diagram depicts. See .
9. Drag and drop actors, classes, and interfaces onto the diagram to create objects for interaction. See .
10. Add messages between the objects. See .
11. Describe each message. See .
12. To describe how the object behaves when it receives the message, assign an operation to the message. See .

Alternatively, if you are not maintaining a separate Analysis Model, you may decide to modify your existing sequence diagrams to reflect the evolution of the design elements.

For more information, refer to .

Simplify Sequence Diagrams Using Subsystems (optional)

See the previous step for guidance on working with sequence diagrams.

Describe Persistence-Related Behavior

Persistence mechanisms are ideally described using patterns. See the following topics in the Rational XDE online Help:

Refine the Flow of Events Description

Additional description can be added to the sequence diagrams for clarification. Text can be added anywhere on the diagram. Notes can be added and attached to shapes on the diagram. Consider using the RUP-provided template for Artifact: Use Case Realization.

Refer to , , and in the Rational XDE online Help.

Unify Design Classes and Subsystems

As use cases are realized, you must unify the identified design classes and subsystems to ensure homogeneity and consistency in the Design Model.

Part of unifying the design is identifying common patterns that can be factored out and reused. See the following topics in the Rational XDE online Help:

Evaluate the Results

There is no Rational XDE specific guidance for this step.