Waterfall Model

Waterfall ModelSDLC approachBecame popular in 1970Phases are organised in Linear

OrderOutput of one phase is input for

next phase

Waterfall Model Phases

Proposal Definition Feasibility Study Requirements Analysis System Design Coding & Testing Implementation System Maintenance

Waterfall Model

RequirementsAnalysis

System Design

Coding & Testing

Implementation

Systemmaintenance

Proposal Definition

Feasibility Study

Strengths of Waterfall Model

Easy to understand, easy to useSystematic for inexperienced staffMilestones are well understood

Strengths of Waterfall Model

Sets requirements stabilityGood for management control (plan,

staff, monitor, control)Works well when quality is more

important than cost or schedule

Limitations-Waterfall Model

Every phase is considered as a distinct phase

All requirements must be known before hand

Deliverables created for each phase are considered frozen – reduces flexibility

Limitations-Waterfall Model

Can give a false impression of progress

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

Limitations-Waterfall Model

For a new system determining requirements is a difficult job

So freezing requirements before design is not practical

Might be desirable to built only a part of it

Later enhance as and when needed

Limitations-Waterfall Model

Freezing requirements requires choice of H/W

In large projects, technology changes when the system is completed

Limitations-Waterfall Model

Difficulty of accommodating change after the process is underway

One phase has to be complete before moving onto the next phase

Integration is one big bang at the end

Limitations-Waterfall Model

Inflexible partitioning of the project into distinct stages makes it difficult to change as per customer requirements.

Requirements should be well-understood so that changes are fairly limited during the design process

When to use?Requirements are very well

knownProduct definition is stableTechnology is understood

When to use?New version of an existing

productPorting an existing product to

a new platform.

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