the software development process -- iwebhome.cs.uvic.ca/~hausi/110/book/pdf/chap11.pdf · –...

Java Software Solutions Lewis and Loftus

Chapter 11

1

Copyright 1997 by John Lewis and William Loftus. All rights reserved.

The Software Development Process -- In

•The quality of the software we create is a d

the process we follow to develop it

•Chapter 11 focuses on:

–software life cycle

–development models

–prototypes

–robot search problem


Chapter 11

2


The Program Life Cycle

•The overall life of a program includes use a

maintenance:

Use

Development

Maintenance


Chapter 11

3


Maintenance

•Maintenance tasks include any modifications

existing program

•It includes defect removal and enhancements

•The characteristics of a program that make i

develop also make it easy to maintain

•Maintenance efforts tend to far outweigh the

development effort in today’s software

•Small increases in effort at the development

greatly reduce maintenance tasks


Chapter 11

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Development vs. Maintenance

Use and

Maintenance

Development


Chapter 11

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Development and Maintenance Effort

Development

Maintenance

Development Maintenance


Chapter 11

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Development Process Models

•Too many programmers follow a build-and-fix

approach

•They write a program and modify it until it

without regard to system design

•Errors are haphazardly addressed as they are

•It is not really a development model at all


Chapter 11

7


The Build-and-Fix Approach

Write

program

Modify

program


Chapter 11

8


The Waterfall Model

•Developed in the mid 1970s

•Activities that must be specifically address

development include:

–Establishing clear and unambiguous requirements

–Creating a clean design from the requirements

–Implementing the design

–Testing the implementation

–

•Originally it was proposed as a linear model

or no backtracking

•It is a nice goal, but unrealistic


Chapter 11

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The Waterfall Model

Establish

requirements

Create

design

Implement

code

Test

system


Chapter 11

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An Iterative Process

•Allows the developer to cycle through the di

development stages

•Essentially the waterfall model with backtra

•However backtracking should not be used as a

•It should be used as a technique available t

developer in order to deal with unexpected p

may arise in later stages of development


Chapter 11

11


An Iterative Development Process

Establish

requirements

Create

design

Implement

code

Test

system


Chapter 11

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Prototype

•A program created to explore a particular co

•More useful, time-effective, and cost-effect

merely acting on an assumption that may late

•Usually created to communicate to the client

–a particular task

–the feasibility of a requirement

–a user interface

–

•A way of validating requirements


Chapter 11

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An Enhanced Iterative Model

Establish

requirements

Create

design

Implement

code

Test

system

Prototype

Prototype

Prototype

Prototype

Evaluate

Evaluate

Evaluate

Evaluate


Chapter 11

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Evaluation

•The results of each stage should be evaluate

prior to going on to the next stage

•Before moving on to the design, for example,

requirements should be evaluated to ensure

completeness, consistency, and clarity

•A design evaluation should ensure that each

was adequately addressed

•Prior to testing, the implementation should

thorough

code walkthrough


Chapter 11

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Testing Techniques

•Goal: to find errors

•Called

defect testing

•A good test will uncover problems in a progr

•A test case includes

–a set of inputs

–user actions or other initial conditions

–expected output

–

•It is not feasible to exhaust every possible


Chapter 11

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Black-Box Testing

•Mapping a set of specific inputs to a set of

outputs

•An equivalence category is a collection of i

•Two input sets belong to the same equivalenc

if there is no reason to believe that if one

other will not

•Therefore testing one input set essentially

category


Chapter 11

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White-Box Testing

•Also referred to as glass-box testing

•Focuses on the internal logic such as the im

of a method

•Statement coverage guarantees that all state

method are executed

•Condition coverage guarantes that all paths

method are executed


Chapter 11

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Robot Search Simulator

•We’ll now explore a large example and follow

the various development activities

•Robot Search Problem

–a robot is sent into a hazardous area to find a ta

–we must develop a simulator to test its search alg

–the results will be shown graphically

–walls and other barriers must be taken into accoun


Chapter 11

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Robot Search Requirements

•The robotic engineers provide an initial set

requirements

•The initial set are unclear and leave many q

unanswered

•The developers interview the engineers to re

and create a new version of the requirements

•They are reviewed and critiqued


Chapter 11

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Robot Search Design

•The design itself should be an iterative pro

•An initial set of objects is chosen based on

requirements

•As the design develops the apparent need for

objects arises

•Objects are abstracted into classes

•Focus is on the overall structure of the pro


Chapter 11

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Robot Search Design

•Initial classes:

Robot

move ()

draw ()

Goal

draw ()

Obstacle

draw ()


Chapter 11

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A Class Hierarchy for Robots

Robot

Random_Robot

Diagonal_RobotSpiral_Robot

Vertical_Robot


Chapter 11

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A Scenario Diagram

Robot_Sim

Random_Robot

Goal

Obstacle

1: detect_goal()

3: move()

2: collision()

4: collision()


Chapter 11

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Changing Robot Position

1, 1

1, 0

0, 1

1, -1

-1, 1

-1, 0

0, -1

-1, -1


Chapter 11

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Robot Search Design

•The developers have only limited knowledge o

processing

•A prototype is developed to:

–load an image

–move it across the screen

–test animation speeds

–

•This is called a proof-of-concept prototype,

developers continue with confidence

•


Chapter 11

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Robot Search Implementation

•The classes of the design are implemented in

files:

–Robot_Sim.java

–Robot.java

–Diagonal_Robot.java

–Goal.java

–Obstacle.java

–

•Each one contains a particular class or clas


Chapter 11

27


Collision Detection

Obstacle

the software development process -- iwebhome.cs.uvic.ca/~hausi/110/book/pdf/chap11.pdf · –...

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