The document discusses the waterfall model as a software process model. It describes the waterfall model as having sequential steps of communication, planning, modeling, construction, and deployment. A variation called the V-model is also described which pairs verification and validation actions with earlier engineering actions. The advantages of the waterfall model include being a classic life cycle model and useful when requirements are fixed. Disadvantages include that real projects are rarely sequential and a working model is not available until late. Applications provided include building a car where requirements are predefined and stages are completed sequentially.

1. ALPHA BREATHING

3. Process Models: The Waterfall Model

4. Software Process
When you work to build a product or a system, it’s important to go
through a series of predictable steps - a roadmap that helps you to
create a timely, high-quality result.
The roadmap that you follow is called a “software process”.

5. Process model
A process is defined as a collection of work activities, actions and tasks that
are performed when some work product is to be created.
Each of these activities, actions, and tasks reside within a framework or model
that defines their relationship with the process and with one another.

6. Types of Software Process Models
• The Waterfall model
• The Incremental model
• Evolutionary process models:
• Prototyping model
• The spiral model
• Concurrent process model

7. Characteristics of Waterfall Model
• Called as classic life cycle model.
• This Model suggests a systematic, sequential approach to software
development.
• Software is developed as a whole.
• Used when requirements are well understood in the beginning.

8. Steps in Waterfall Model
1. Communication
2. Planning
3. Modeling
4. Construction
5. Deployment

9. Waterfall Model & The V-Model

10. Contd..
A variation in the representation of waterfall model is called the V-
model.
V-model depicts the assurance actions to the actions associated with
communication, modeling and early construction activities.
Once code has been generated, the team moves up the right side of V,
essentially performing a series of tests that validate each of the models
created as the team moved down left side.
In reality, the is no difference between the waterfall and the V- model.
The V- model illustrates how verification and validation actions are
associated with earlier engineering actions.

11. Advantages
• Classic life cycle model
• Useful in situations where requirements are fixed and proceed to
completion in linear manner

12. Disadvantages
• There are also some disadvantages of waterfall model:
Real projects rarely follow the sequential flow since they are
always iterative.
The model requires requirements to be explicitly spelled out in
the beginning, which is often difficult.
The customer must have patience. A working model is not
available until late in the project time plan.
Leads to ‘Blocking States’.

13. Applications
We can take real life examples for water fall model like automobile
companies -
When they are building a car, the requirements are fixed,
predefined.
There will be no change in the requirements during the process of
building a car.
Once we complete a stage, we proceed to the next one.

14. MIND MAP

15. SUMMARY
Software Process Models
 Waterfall Model
 Communication
 Planning
 Modeling
 Construction
 Deployment
 The V-Model
• Advantages
• Disadvantages
• Applications

16. Stimulating Question
• Waterfall model is the most widely used process model than
incremental process model- Justify your answer.
ANS:
• Real projects rarely follow the sequential flow since they are always
iterative.
• Compared to waterfall, iterative development allows flexibility in
accommodating new requirements or changes thereof. It also
provides room for improvement in succeeding iterations based on
lessons learned from previous iterations.