CHAPTER ONECHAPTER ONEProblem Solving

© Prepared By:Razif Razali 1

“ Do Something. If it doesn’t work, do something else. No idea is too crazy”

- Jim Hightower

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OBJECTIVESOBJECTIVES

To list types of software development life cycle (SDLC).

To understand the use of SDLC.To differentiate between types of

SDLC approach.To have a view the use of

programming tool

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What is Software?What is Software?

Instructions (computer programs) that when executed provide desired function and performance

Data structures enable the programs to adequately manipulate information

Documents that describe the operation and use of the program

Software engineering : A Practitioner's Approach

A definition of the software development:

The application of a systemic, disciplined, quantifiable approach to development, operation, and maintenance of software.

EEE Standard Computer Dictionary, 610,

ISBN 1-55937-079-3 Software Engineering: A Practitioner's Approach

Who’s Who

CUSTOMER Sponsors systemdevelopment

USER

Usessystem

DEVELOPER

Buildssystem

Contractualobligation

$$$,needs

Software system

Needs

What is the Software Life Cycle?

Software Engineering is a series of steps for producing software.

Methods, procedures, and tools are defined.

Engineering discipline

Metrics and measures - prediction

Classic Life Cycle ModelsLinear sequential (Waterfall)PrototypingRapid Application Development

(RAD) Incremental (Block Release)SpiralComponent AssemblyConcurrent DevelopmentFourth Generation techniques

Waterfall Model

REQUIREMENTSANALYSIS

SYSTEMDESIGN

PROGRAMDESIGN

CODING

UNIT & INTE-GRATION TESTING

SYSTEMTESTING

ACCEPTANCETESTING OPERATION

& MAINTENANCE

Waterfall Strengths

Easy to understand, easy to useProvides structure to inexperienced staffMilestones are well understoodSets requirements stabilityGood for management control (plan, staff,

track)Works well when quality is more important

than cost or schedule

Waterfall Deficiencies

All requirements must be known upfrontDeliverables created for each phase are

considered frozen – inhibits flexibilityCan give a false impression of progressDoes not reflect problem-solving nature of

software development – iterations of phases

Integration is one big bang at the endLittle opportunity for customer to preview

the system (until it may be too late)

When to use the Waterfall Model?

Requirements are very well knownProduct definition is stableTechnology is understoodNew version of an existing productPorting an existing product to a new

platform.

“Interactive” (Chaotic) Model

REQUIREMENTSANALYSIS

SYSTEMDESIGN

PROGRAMDESIGN

PROGRAMIMPLEMENTATION

UNITTESTING

INTEGRATIONTESTING

SYSTEMTESTING

DELIVERY

MAINTENANCE

Waterfall with PrototypingWaterfall with Prototyping

REQUIREMENTSANALYSIS

SYSTEMDESIGN

PROGRAMDESIGN

CODING

UNIT & INTE-GRATION TESTING

SYSTEMTESTING

ACCEPTANCETESTING OPERATION

& MAINTENANCE

PROTOTYPING

Verify

Validate

Prototyping Cycles

LIST OFREVISIONS

LIST OFREVISIONS

LIST OFREVISIONS

PROTOTYPEREQUIREMENTS

PROTOTYPEDESIGN

PROTOTYPESYSTEM

TEST

DELIVEREDSYSTEMSYSTEM

REQUIREMENTS(sometimes informal

or incomplete)

reviseprototype

user/customer

review

Structured Evolutionary Prototyping Model

Developers build a prototype during the requirements phase

Prototype is evaluated by end usersUsers give corrective feedback Developers further refine the prototypeWhen the user is satisfied, the

prototype code is brought up to the standards needed for a final product.

Multiple Builds

Development systems

Production systems

DEV

ELO

PER

SU

SER

S

Build Release 1

Use Release 1

Build Release 2

Use Release 2

Build Release 3

Use Release 3

Time

Spiral Model

Start Axis

Customer Communication

Planning

Risk Analysis

Development

Integration

Customer Evaluation

Spiral Model Strengths

Provides early indication of insurmountable risks, without much cost

Users see the system early because of rapid prototyping tools

Critical high-risk functions are developed firstThe design does not have to be perfect Users can be closely tied to all lifecycle stepsEarly and frequent feedback from usersCumulative costs assessed frequently

Spiral Model Weaknesses

Time spent for evaluating risks too large for small or low-risk projects

Time spent planning, resetting objectives, doing risk analysis and prototyping may be excessive

The model is complex Risk assessment expertise is requiredSpiral may continue indefinitelyDevelopers must be reassigned during non-

development phase activitiesMay be hard to define objective, verifiable

milestones that indicate readiness to proceed through the next iteration

Rapid Application Development (RAD)

A good model for small VB systemsThe IDE is designed to allow us to

develop the small system.

Rapid Application Model (RAD)Rapid Application Model (RAD)

Requirements planning phase (a workshop utilizing structured discussion of business problems)

User description phase – automated tools capture information from users

Construction phase – productivity tools, such as code generators, screen generators, etc. inside a time-box. (“Do until done”)

Cutover phase -- installation of the system, user acceptance testing and user training

RAD Strengths

Reduced cycle time and improved productivity with fewer people means lower costs

Time-box approach mitigates cost and schedule risk

Customer involved throughout the complete cycle minimizes risk of not achieving customer satisfaction and business needs

Focus moves from documentation to code (WYSIWYG).

Uses modeling concepts to capture information about business, data, and processes.

RAD Weaknesses

Accelerated development process must give quick responses to the user

Risk of never achieving closure Hard to use with legacy systemsRequires a system that can be modularizedDevelopers and customers must be committed to

rapid-fire activities in an abbreviated time frame.

“You’ve got to be very careful if you don’t know where you’re going, because you might not get there.”

- Yogi Berra

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PROGRAMMING TOOL

A programming tool or software development tool is a program or application that software developers use to create, debug, maintain, or otherwise support other programs and applications.

The term usually refers to relatively simple programs that can be combined together to accomplish a task, much as one might use multiple hand tools to fix a physical object.

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CATEGORIES

Software development tools can be roughly divided into the following categories:◦ performance analysis tools◦ debugging tools◦ static analysis and formal verification tools◦ correctness checking tools◦ memory usage tools◦ application build tools◦ integrated development environment

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LIST OF TOOLLIST OF TOOL

Compilation and linking tools: GNU toolchain, Microsoft Visual Studio, CodeWarrior, ICC

Scripting languages: Awk, Perl, Python, REXX, Ruby, Shell, Tcl Search: grep, find

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SUMMARY

Types of SDLC approach.The differences between the

approaches.The use of programming tools

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END OF CHAPTER ONEEND OF CHAPTER ONE

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