The waterfall model is a linear sequential development process where each phase must be completed before the next can begin. It has six phases: requirements analysis, system design, implementation, integration testing, deployment, and maintenance. While it provides structure, all requirements must be known upfront and it does not allow for flexibility if requirements change. It is best for projects with stable requirements where quality is more important than cost or schedule.

1. Waterfall Model
Presented by:
Fatima Qayyum (011)
Mahnoor Shaukat (020)
Laraib Tahira (057)

2. Waterfall Model
o Introduced by Winston W. Royce in 1970.
o The waterfall model is the classic lifecycle
model.
o Linear sequential model.
o Whole system is developed in a sequential
approach.
o Each phase is completed fully before the next
begin.
o Provides structure to inexperienced staff.

3. Cont.
Each phases produces documents that are:
o Verified and validated.
o Assumed to be complete.
A phase takes place in sequence to another.
Each activity is completed before the next starts.
Each phase depends on the documents of the previous stage to
precede.
Emphasize planning before action.
Recommend a top-down perspective.
See the big picture before zooming down.

4. Features
o A Water Fall Model is easy to flow.
o Requirements are completely frozen.
o It can be implemented for any size of project.
o Every stage has to be done separately at the right time so
you cannot jump stages.
o Documentation is produced at every stage of a waterfall
model allowing people to understand what has been done.
o Testing is done at every stage.

5. Stages of Waterfall
Model
It has 6 phases and they are:
i. Requirement Analysis
ii. System Design
iii. Implementation and Unit Testing
iv. Integration and System Testing
v. Deployment
vi. Maintenance

6. 1st Stage: Requirement Analysis
o Define needed Information, Function, behaviour,
performance & interface.
o Meetings between customer and developer.
o This is the most crucial phase.
o Software definition to be detailed and accurate with
no ambiguities.
o Understand to meet customer specifications.
o Documented requirements and reviewed.

7. 2nd Stage: System Design
o Blue print of the software.
o Physical and logical design of the project.
o All details about:
o Data structures
o Algorithms
o Interface
o The activity and behavior of the software.
o It should be documented.

8. 3rd Stage: Implementation & unit Testing
o In this stage actual coding is started.
o The system is first developed in units.
o According to design programmers do code .
o Documentation and module testing is also done in
this phase.

9. 4th Stage: Integration & System Testing
o All the units are integrated into a system after testing
of each unit.
o Post integration the entire system is tested for any
faults and failures.
o The modules are integrated into a complete system
and tested to check if all modules cooperate as
expected.

10. 5th Stage: Deployment
o Once testing is done the:
o product is deployed in the customer environment
o or released into the market.
o User training is also done in this stage.

11. 6th Stage: Maintenance
o Software development team undertake routine
maintenance activities by visiting the client site.
o The usually the never ending stage of the software.
o In this phase the software is updated to:
o Meet the changing customer needs
o Adapted to accommodate changes in the external
environment
o Correct errors and oversights previously undetected in
the testing phases

12. 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.

13. Advantages Disadvantages
o Easy to understand, easy to use
o Provides structure
o Milestones are clear
o Good for management control (plan,
staff, track)
o Works well when quality is more
important than cost or schedule
o All requirements must be known upfront
o Deliverables created for each phase are
considered frozen – inhibits flexibility
o Can give a false impression of progress
o Does not reflect problem-solving nature
of software development , i.e. iterations
of phases
o One big integration at the end

14. Problems
 Specification is frozen early, because:
It is costly and time consuming.
Later stages can be carried out.
 Cannot adapt to changing or incorrect specification:
Ignore or code around.
Does not meet user requirement.
 Testing at the very end of development:
Work or die situation.
This Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY

15. Conclusion
o Whether you should use it or not depends
largely on:
How well you understand customer's needs
How much volatility you expect in those needs
as the project progresses
o The model is recommended for use only in
projects which are relatively stable and
where customer needs can be clearly
identified at an early stage.