Software Development life

cycle

Dushyant singh

Introduction • It specifies the various phases/workflows of the software process, such as the requirements, analysis (specification), design, implementation, and postdelivery maintenance, and the order in which they are to be carried out.

Choosing Appropriate model • Increased development speed • Increased product quality • Improved tracking & control• Improved client relations • Decreased project risk • Decreased project

management overhead

Common life cycle model

• Waterfall• Prototype • Spiral

Waterfall model

Analysis

DesignDevelopment

Testing

VerificationMAINTENANCE

Waterfall plus points

• Easy to understand, easy to use

• Provides structure to inexperienced staff

• Milestones are well understood

• Sets requirements stability

Waterfall weakness• All requirements must be fully

specified upfront • Can give a false impression of

progress• Does not reflect problem-

solving nature of software development – iterations of phases

• Little opportunity for customer to preview the system (until it may be too late)

Prototype model

DesignImplement

TestMaintain

Requirementsgathering

Quick design

Build prototype Refine requirements incorporating

Customer suggestion

Customer evaluationOf prototype

AcceptanceBy

customer

Prototypedevelopm

ent

Iterativedevelopme

nt

Prototype advantages • Provides a working model to the

user early in the process , enabling early assessment and increasing user confidence.

• The developer gains experience and insight by developing a prototype , thereby resulting in better implementation of requirements.

• Helps in reducing risks associated with the project.

Spiral model

Spiral model is an evolutionary software process model which is a combination of an iterative nature of prototyping and systematic aspects of traditional waterfall model.

When Required ?

• When costs and risk evaluation is important.

• For medium to high-risk projects.

• Users are unsure of their needs.• Requirements are complex.• Significant changes are

expected.

pros • Changing requirements can be

accommodated.• Allows for extensive use of

prototypes• Requirements can be captured more

accurately.• Users see the system early.• Development can be divided into

smaller parts and more risky parts can be developed earlier which helps better risk management.

cons• Management is more complex.• End of project may not be known

early.• Not suitable for small or low risk

projects and could be expensive for small projects.

• Process is complex• Spiral may go indefinitely.• Large number of intermediate

stages requires excessive documentation.

Thank you