Page 68 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN

Object Oriented Analysis and Design Anil Sharma, Lovely Professional University

Notes Unit 6: State Modelling

CONTENTS
Objectives

Introduction
6.1 State Machine
6.1.1 Events

6.1.2 States
6.1.3 Transition and Conditions
6.1.4 Action
6.1.5 Activity

6.2 State Diagrams
6.2.1 When to use State Diagrams

6.2.2 How to draw State Diagrams
6.2.3 State Diagram Behaviour
6.3 Summary
6.4 Keywords

6.5 Review Questions
6.6 Further Readings

Objectives

After studying this unit, you will be able to:

Explain the concept of events and states
Discuss the concept of transitions and conditions
Describe State Diagrams

Explain State Diagram Behaviour
Introduction

The complete OOM revolves around the objects identified in the system. When observed closely,
every object exhibits some characteristics and behavior. The objects recognize and respond to
certain events. For example, considering a Window on the screen as an object, the size of the
window gets changed when resize button of the window is clicked. Here the clicking of the
button is an event to which the window responds by changing its state from the old size to the
new size. While developing systems based on this approach, the analyst makes use of certain
models to analyze and depict these objects. The dynamic model represents a state/transition
view on the model. Main concepts are states, transitions between states, and events to trigger
transitions. Actions can be modeled as occurring within states. Generalization and aggregation
(concurrency) are predefined relationships. The outcomes of a dynamic model are scenarios,
event-trace diagrams and state diagrams.

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