The document discusses different software development life cycle (SDLC) models: waterfall model, iterative model, and spiral model. It provides details on each model type, including their process steps, merits, demerits, and when each is best used. The waterfall model follows sequential phases of requirements, design, implementation, testing, and maintenance. The iterative model repeats the waterfall phases for incremental releases. The spiral model is risk-driven and iterative, with each loop consisting of planning, risk analysis, development, and evaluation.

1. Soft Skills
And
Personality Development

2. Software
Development Life
Cycle (SDLC)

3. A framework that describes the activities
performed at each stage of a software
development project.

4. There are 3 types of SDLC
models
•Waterfall Model
•Iterative Model
•Spiral Model

5. 1.Waterfall Model
• Requirements – defines needed information, function, behavior,
performance and interfaces.
• Design – data structures, software architecture, interface
representations, algorithmic details.
• Implementation – source code, database, user documentation,
testing.
• Test- testing the application for errors so that application
becomes error free
• Maintenance- maintaining the software for additional features

6. Analysis
Design
Code
Testing
Maintenance

7. Waterfall Merits and Demerits
Easy to understand, easy to use
Provides structure to
inexperienced staff
Sets requirements stability
Good for management control
(plan, staff, track)
Works well when quality is more
important than cost or schedule
 Inhibits flexibility-Deliverables
created for each phase are
considered frozen, i.e. Customer
has to wait up to last stage for any
modifications.
Can give a false impression of
progress
Little opportunity for customer
to preview the system (until it
may be too late).

8. When to use the Waterfall
Model
 Requirements are very well known
 Product definition is stable
 Technology is understood
 New version of an existing product
 Porting an existing product to a new platform.
 High risk for new systems because of specification and
design problems.
 Low risk for well-understood developments using familiar
technology.

9. 2. Iterative Enhancement
Model
• It helps to remove the short comings of the
waterfall model
• The phase of the software development remains
the same, but the construction and delivery is
made in repetitive mode
• In the first iteration, a less capable product are
developed and delivered for use and so on

10. Iteration
1
Iteration
2…
Iteration
n
Release
to client
fig. Iterative Enhancement
Model
Waterfall
model
Basic Model
Product 1
Waterfall
model
Enhanced
Changes
Product 2
Waterfall
model
Enhanced
Changes
Product 3
Finally
Release to
client

11. Iterative Merits and Demerits
Very Useful when less man
power is required and release
deadlines are tight.
It is best suited for in house
product development.
It is ensured that the user has
something to start with
 Iteration may never end
User may have to endlessly
wait for the final product
The cost estimated is also
high because it is difficult to
relate the software
development cost with the
number of requirements

12. 3.Spiral Model
• In 1988 Boehm developed the spiral model as an iterative model
which includes risk analysis and risk management.
• Here each loop in the spiral represents a phase of the software
process
• Each cycle involves the same sequence of steps as the waterfall
process model
Key idea: on each iteration identify and solve
the sub-problems with the highest risk.

13. Risk
analysis
Risk
analysis
Risk
analysis
Risk
analysis Proto-
type 1
Prototype 2
Prototype 3
Opera-
tional
protoype
Concept of
Operation
Simulations, models, benchmarks
S/W
requirements
Requirement
validation
Design
V&V
Product
design Detailed
design
Code
Unit test
Integration
testAcceptance
testService Develop, verify
next-level product
Evaluate alternatives
identify, resolve risks
Determine objectives
alternatives and
constraints
Plan next phase
Integration
and test plan
Development
plan
Requirements plan
Life-cycle plan
REVIEW

14. Spiral Quadrant: Determine
objectives, alternatives and
constraints
• Objectives: functionality,
performance,
hardware/software
interface, critical success
factors, etc.
• Alternatives: build, reuse,
buy, sub-contract, etc.
• Constraints: cost,
schedule, interface, etc.
Spiral Quadrant: Evaluate
alternatives, identify and
resolve risks
• Study alternatives relative to
objectives and constraints
• Identify risks (lack of
experience, new technology,
tight schedules, poor process,
etc.
• Resolve risks (evaluate if
money could be lost by
continuing system
development

15. • Typical activities:
• Create a design
• Review design
• Develop code
• Inspect code
• Test product
Spiral Quadrant:
Develop next-level
product
Spiral Quadrant:
Plan next phase
• Typical activities
• Develop project plan
• Develop configuration
management plan
• Develop a test plan
• Develop an installation
plan

16. Spiral Model Strengths
Provides early indication of insurmountable
risks, without much cost
Critical high-risk functions are developed first
The design does not have to be perfect
Users can be closely tied to all lifecycle steps
Early and frequent feedback from users
Cumulative costs assessed frequently

17. 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 required
Spiral may continue indefinitely

18. Any Questions
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