Unit II – Software Process & Requirements Modeling

 

Introduction to Software Engineering

Software engineering is all about building quality software that meets people’s needs efficiently.
Software plays two big roles today:

• As a product – it performs tasks like calculations, communication, or media handling.

• As a vehicle – it controls systems like operating systems, networks, or tools.

  
  
  

Nature of Software

Software is everywhere — from your phone to airplanes. Over time, it has grown more complex due to faster hardware, bigger memory, and smarter devices.

But the same big questions remain:

1. Why does software take so long to build?

2. Why is it so expensive?

3. Why can’t we fix all errors early?

4. Why is maintenance so hard?

5. Why is progress tough to measure?

   
   
   

Types of Software Applications

There are seven main categories of software:

1. System Software – runs other programs (like compilers, editors).

2. Application Software – solves specific tasks (e.g., billing systems).

3. Engineering/Scientific Software – for calculations and simulations.

4. Embedded Software – found in devices like cars and washing machines.

5. Product-line Software – used by many users (e.g., MS Word, Excel).

6. Web Applications (WebApps) – everything you use online.

7. Artificial Intelligence Software – mimics human intelligence (e.g., chatbots, robots).

   
   
   

 Legacy Software

Older programs still in use are called legacy systems.
They’re important but difficult to maintain. They often need:

• Adaptation for new technologies

• Enhancements for business needs

• Interoperability with modern tools

• Redesign for web and cloud use

  
  
  

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Software Engineering Basics

To build modern software, engineers follow a few realities:

• Software is everywhere → Understand the problem first.

• Complex needs → Focus on good design.

• High dependency → Ensure quality.

• Long lifespan → Make it maintainable.

  
  
  

 The Practice of Software Engineering

Every project follows these key stages:

1. Understand the problem – Who needs it and what’s required?

2. Plan a solution – Design before coding.

3. Carry out the plan – Write and test the code.

4. Examine the result – Test for quality and correctness.

   
   
   

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 Key Principles by David Hooker

1. Provide Value – Every system exists to help users.

2. KISS (Keep It Simple, Stupid!) – Simplicity = better maintenance.

3. Maintain the Vision – Stay clear on the project goal.

4. Think of Others – Your code should be easy to understand.

5. Be Open to the Future – Plan for flexibility.

6. Plan for Reuse – Reusable code saves time.

7. Think Before You Code – Smart planning leads to success.

   
   
   

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 Software Testing Levels

1. Unit Testing – Test small pieces of code.

2. Integration Testing – Check how modules work together.

3. System Testing – Test the entire application.

4. Acceptance Testing – Confirm if it meets business goals.

   
   
   

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 Software Development Models

• Prototyping Model – Build a small model first, then improve it.

• Spiral Model – Develop in cycles, reducing risks gradually.

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Capability Maturity Model (CMM)

CMM measures how mature a software process is — from initial chaos to optimized excellence.

🟡 Initial – Unpredictable and reactive.
1. 🟠 Repeatable – Basic project management and tracking.
2. 🔴 Defined – Standardized and documented processes.
3. 🔵 Managed – Metrics-driven and controlled.
4. 🟢 Optimizing – Continuous improvement and innovation.

This model is often used in frameworks like CMMI to assess organizational maturity. Let me know if you'd like to customize it with icons, animations, or add real-world examples for each level!