This document discusses different software development life cycle (SDLC) models. It describes the waterfall model as having distinct phases including requirements definition, design, implementation, testing, and maintenance. The iterative model develops software incrementally in iterations. The spiral model involves risk assessment and reduction at each phase through objective setting, development/validation, and planning. The document compares the advantages and disadvantages of each model.

1. SOFTWARE DEVELOPMENT
LIFE CYCLE
BY ASHUTOSH THAPA

2. INTRODUCTION
 Software is said to have a life cycle composed of several phases.
 Each phases has a well defined starting and ending points with
clearly identifiable deliverables to the next phase.
 Software development life cycle describes a process used by
engineers and analyst to develop and deploy all aspects of an
information system.
 Sequence of activities carried out by analyst, designer and user to
develop an information system.

3. SDLC MODELS
 WATERFALL MODEL
 SPIRAL MODEL
 ITERATIVE MODEL

4. WATERFALL MODEL

5. WATERFALL MODEL
 REQUIREMENT DEFINITION :- the program developer and the client sit together to discuss
the requirements.
 SYSTEM AND SOFTWARE DESIGN :- the designer according to the given requirement makes
database,modules,forms etc.
 IMPLEMENTATION AND UNIT TESTING :- Here actual coding is started. The system is first
developed in small programs called unit.
 INTEGRATION AND SYSTEM TESTING :- In this phase the units are integrated into a complete
system.
 OPERATIONS AND MAINTENANCE :- In this phase the system is put into practical use.

6. ADVANTAGE AND DISADVANTAGE
 ADVANTAGE
 Easy to understand and implement.
 Widely used and known.
 DISADVANTAGE
 It is linear (Works sequentially).
 It is rigid (its not flexible).
 System requirement is needed early in the project.

7. ITERATIVE MODEL

8. ITERATIVE MODEL
 Software is developed in increments.
 Project control lists keeps tracks of task.
 Each increment deletes the previous increment from project control list.

9. ADVANTAGE AND DISADVANTAGE
 ADVANTAGE
 Better testing.
 Combines the principles of both prototyping and waterfall models.
 DISADVANTAGE
 Iteration may be very long process.
 Costly system architecture as there is always a need to improve.

10. SPIRAL MODEL

11. SPIRAL MODEL
 OBJECTIVE SETTING :-Specific objectives for that phase of the project
are defined.
 RISK ASSESMENT AND RISK REDUCTION :-For each of the identified
project risks, a detailed analysis is carried out.
 DEVELOPMENT AND VALIDATION :-After risk evaluation, a development
model for the system is chosen.
 PLANNING :-The project is reviewed and a decision made whether to
continue with a further loop of the spiral.

12. ADVANTAGE AND DISADVANTAGE
 ADVANTAGE
 High amount of risk analysis.
 Good for large and mission-critical projects.
 DISADVANTAGE
 Cost id high.
 Doesn’t work well for smaller projects.
 It is not suitable for low risk projects.

13. THANK YOU