Lecture 2 contains software process, models, waterfall model

1. Software Process
and Process Models

2. Lecture Outline
Software Process
Software Process Models
Waterfall Model

3. Lecture Contents
 What is Software?(Recall)
 What is a Software Process?
 Why Do We Need a Software Process?
 Generic Activities in a Software Process
 Umbrella Activities (Brief Reminder)
 What is a Software Process Model?
 Why Do We Need Process Models?
 Common Software Process Models
 What is the Waterfall Model?
 Phases of the Waterfall Model.
 Advantages and Disadvantages of the Waterfall Model.

4. What is Software?
Before defining software process, recall what software is.
Software is not just a program. It includes:
• Programs (code)
• Documentation
• Data
• User manuals
• Configuration files
So, building software is more than writing code.

5. What is Software?
Software is a collection of instructions, data, or
programs that tell a computer or device how to
operate and perform specific tasks. It acts as the
bridge between human needs and machine
capabilities, controlling the physical hardware.

6. What is a Software Process?
A software process is a structured set of activities
required to develop, operate, and maintain software.
In simple words:
Software process is the step-by-step method used to
build software in a disciplined way.

7. Why Do We Need a Software
Process?
Without a defined process:
Development becomes chaotic
Deadlines are missed
Quality is poor
Cost increases
Requirements change uncontrollably

8. Why Do We Need a Software
Process?
A software process helps:
Plan work properly
Control cost and time
Improve software quality
Make work repeatable and manageable

9. Everyday Analogy
Think of cooking a meal.
If you cook without a recipe:
You may forget ingredients
Food quality is inconsistent
A recipe is like a software process.

10. Generic Activities in a Software
Process
Most software processes include the following framework activities:
1. Communication
Understanding customer requirements
Discussing expectations
Example: Client meetings, requirement gathering.
2. Planning
Estimating time, cost, and resources
Creating schedules
Example: Project plan, timeline, milestones

11. Generic Activities in a Software
Process
3. Modeling
Designing the system
Creating architecture and data models
Example: Flowcharts, UML diagrams.
4. Construction
Coding and testing
Writing actual software
Example: Writing C/Java/Python code and testing it.

12. Generic Activities in a Software
Process
5. Deployment
Delivering software to users
Getting feedback
Example: Installing software, releasing updates

13. Umbrella Activities (Brief Reminder)
These run throughout the process:
Project tracking
Risk management
Quality assurance
Configuration management
Documentation

14. Software Process Models
What is a Software Process Model?
A software process model is a representation of the software
process that shows:
Order of activities
Flow between stages
How development progresses
In simple terms:
A process model is a roadmap for software development.

15. Why Do We Need Process Models?
Different projects have different needs:
Small vs large systems
Stable vs changing requirements
Low risk vs high risk
Process models help choose the right development approach.

16. Common Software Process
Models
Some well-known models:
Waterfall Model
Incremental Model
Iterative Model
Spiral Model
Agile Model
V-Model
In this lecture, we focus mainly on the Waterfall Model.

17. Analogy for Process Models
Building a house:
You follow a plan
Foundation first, then walls, then roof
Different houses may need different building plans, just like different
software needs different models.

18. Waterfall Model
What is the Waterfall Model?
The Waterfall Model is a linear and sequential software development
model.
In this model:
Each phase must be completed before the next phase begins
Output of one phase becomes input of the next phase
It looks like a waterfall flowing downward.

19. Diagram Description

20. Phases of the Waterfall Model
(Detailed)
Phase 1: Requirement Analysis
Purpose:
• Understand what the customer wants
Activities:
• Meeting clients
• Collecting requirements
• Writing SRS (Software Requirement Specification)
Output:
• SRS document

21. Phases of the Waterfall Model
(Detailed)
Example:
For a library system:
• Number of users
• Book issue rules
• Search functionality
Analogy:
Writing a shopping list before going to the market.

22. Phases of the Waterfall Model
(Detailed)
Phase 2: System Design
Purpose:
• Decide how the system will be built
Activities:
• System architecture design
• Database design
• Interface design
Output:
• Design documents
• Diagrams

23. Phases of the Waterfall Model
(Detailed)
Example:
Deciding:
• Programming language
• Database type
• System modules
Analogy:
Architect drawing a house blueprint.

24. Phases of the Waterfall Model
(Detailed)
Phase 3: Implementation (Coding)
Purpose:
• Convert design into code
Activities:
• Writing programs
• Unit testing
Output:
• Source code

25. Phases of the Waterfall Model
(Detailed)
 Example:
Writing login module, database module, UI
code
 Analogy:
Actual construction of the house.

26. Phases of the Waterfall Model
(Detailed)
Phase 4: Testing
Purpose:
• Find and fix errors
Activities:
• Unit testing
• Integration testing
• System testing
Output:
• Tested software

27. Phases of the Waterfall Model
(Detailed)
Example:
Checking login errors, incorrect outputs
Analogy:
Inspecting the house for faults before living in it.

28. Phases of the Waterfall Model
(Detailed)
Phase 5: Deployment
Purpose:
• Deliver software to the customer
Activities:
• Installation
• User training
Output:
• Working system at customer site

29. Phases of the Waterfall Model
(Detailed)
Analogy:
Handing over keys to the house owner.

30. Phases of the Waterfall Model
(Detailed)
Phase 6: Maintenance
Purpose:
• Fix issues after delivery
• Add minor improvements
Activities:
• Bug fixing
• Performance improvement
• Updates

31. Phases of the Waterfall Model
(Detailed)
 Example:
Fixing a crash issue reported by users
 Analogy:
Repairing and renovating a house after use.

32. Advantages of the Waterfall Model
 Simple and easy to understand
 Well-structured and disciplined
 Clear documentation
 Easy to manage for small projects
 Suitable when requirements are stable

33. Disadvantages of the Waterfall Model
 Not flexible to changes
 Late testing increases risk
 Customer feedback comes very late
 Not suitable for large or complex projects
 Errors discovered late are costly to fix

34. When Should Waterfall Model Be
Used?
 Small projects
 Clearly defined requirements
 Low-risk systems
 Academic projects
 Government or contract-based systems

35. Thank You
For your attention and patience