Lecture 1: Introduction to Software Engineering

Overview: This lecture introduces the fundamentals of Software Engineering and the Software Development Life Cycle (SDLC).

• Why Software Engineering?
  • Software development is inherently challenging.
  • It is crucial to distinguish between "easy" systems (experimental, single-user) and "hard" systems (commercial products, multiple developers/users).
• Goals of Software Development:
  • Satisfy user requirements (many large-scale ordered systems are delivered but not used).
  • High reliability (bugs are expensive; they can cost money, damage reputation, or even cost human lives, e.g., the Ariane 5 launch bug costing $500 million).
  • Low maintenance costs (maintenance accounts for roughly 65% of overall project costs).
  • Delivery on time, low production costs, high performance, and ease of reuse.
• Types of Maintenance:
  • Corrective: Fixing bugs (21%).
  • Adaptive: Altering software to fit changing software (25%).
  • Perfective: Meeting new requirements (50%).
  • Preventative: Reducing further maintenance (4%).
• The Software Process & SDLC:
  • SDLC is a structured process to design, develop, and test software.
  • Stages of SDLC:
    1. Planning and Requirement Analysis: Creating a roadmap.
    2. Defining Requirements: Documenting needs using a Software Requirement Specification (SRS).
    3. Designing Architecture: Using the SRS to create the Design Document Specification (DDS).
    4. Developing Product: Writing the code using languages like C/C++, Python, or Java.
    5. Product Testing and Integration: Finding and fixing mistakes; writing manuals.
    6. Deployment and Maintenance: Releasing the software and monitoring its performance.
• Software Development Models:
  • Waterfall Model: A linear-sequential life cycle model.
    • Advantages: Simple, clear milestones, well-defined phases, and works well for stable requirements.
    • Disadvantages: Inflexible to changes, limited client involvement, and long delivery time.
  • Agile SDLC Models: Iterative development focusing on sprints and daily scrums.