Tool Mentor: Managing Sequence Diagrams

Purpose

This tool mentor describes how to use Rational Rose® to create sequence diagrams that show the interactions between objects.

Related Rational Unified Process activities

• Activity: Use-Case Analysis

• Activity: Use-Case Design

Overview

The following is a summary of the steps you perform to use sequence diagrams to describe the interactions between objects:

1. Create a sequence diagram under the use case realization.

2. Place the participating objects and actors in the sequence diagram.
3. Describe the messages between the objects.
4. Describe what an object does when it receives a message.

For more details about sequence diagrams, see:

• Sequence Diagrams (Overview) topic in the Rational Rose online help.

• Chapter 4, Introduction to Diagrams and Chapter 9, Interaction Diagrams and Specifications in the Using Rose manual.

1. Create a Sequence Diagram Under the Use Case Realization

When you create a sequence diagram for a use case realization, consider naming the diagram "<use-case name> - <flow type>". This naming convention simplifies future tracing of objects to the use-case realization that they participate in. Also, use the documentation window to enter a brief description of the scenario that the sequence diagram depicts.

2. Place the Participating Objects and Actors in the Sequence Diagram

One of the primary elements of a sequence diagram is an object. An object has state, behavior, and identity. The structure and behavior of similar objects are defined in their common class. Each object in a diagram indicates some instance of a class. An object that is not named is referred to as a class instance. In this step, you:

• Drag and drop actors onto the sequence diagram.

• Add objects to the diagram and identify the classes the to which the objects belong.

3. Describe the Messages between the Objects

A message represents the communication between actors and objects, indicating that an action will follow. It carries information from the source focus of control to the destination focus of control. In a sequence diagram a message icon represents exactly one message. When you create a message, use the documentation field in the Message Specification to describe the message.

4. Describe what an Object Does when it Receives a Message

To enhance a message, you can attach a script to it. Use the Text Box symbol in the sequence diagram toolbar.

 Copyright  ⌐ 1987 - 2000 Rational Software Corporation

Rational Unified Process