Software Engineering Fundamentals

• Software engineering is an engineering discipline concerned with all facets of software production.
• It is important to differentiate between "easy" systems, which involve one developer, one user, and are for experimental use only, and "hard" systems, which involve multiple developers, multiple users, and result in products.

Goals of Software Development

• Good software should deliver the required functionality and performance to the user.
• Software should satisfy user requirements.
• Software should have high reliability.
• Software should have low maintenance costs.
• Software should be delivered on time.
• Software should have low production costs.
• Software should be perform with high performance.
• Good software should be easy to reuse.

Satisfying User Requirements

• Many programs do not meet end-user needs.
• Users struggle to articulate their needs effectively.
• Developers often find it difficult to understand what users want.

High Reliability

• Mistakes in programs, known as bugs, can be costly.
• Bugs can lead to loss of human lives in safety-critical systems, like nuclear reactor controls.
• Bugs can lead to software costs, and poor customer relations.
• Problems with early Windows releases caused significant issues for Microsoft.

Low Maintenance Costs

• Maintenance refers to actions performed on software after it is in use.
• Corrective maintenance involves fixing bugs.
• Adaptive maintenance involves altering software to fit changing software.
• Perfective maintenance involves scaling software to meet new requirements.
• Preventative maintenance involves reducing future maintenance needs.

Software Development Life Cycle (SDLC)

• SDLC is a structured process for designing, developing, and testing high-quality software.
• SDLC is a methodology that defines the entire software development procedure step-by-step.

Stages of SDLC

• SDLC specifies the tasks to be performed by a software engineer or developer at various stages.
• SDLC ensures the product meets customer expectations within budget.
• Prior knowledge of the software development process is vital for developers.

Planning and Requirement Analysis

• Planning acts as a roadmap for the project.
• Requirement analysis identifies project needs.
• This information forms the basis for the project plan.

Defining Requirements

• Listing all software requirements is essential.
• Customers and stakeholders approve these requirements.
• A dedicated document is used for clarity.

Designing Architecture

• The Software Requirements Specification (SRS) guides software construction.
• Data Distribution Services (DDS) documents various building ideas.
• The best idea from DDS is selected to move forward.

Developing Product

• Software construction begins based on the chosen design.
• Specific languages such as C/C++, Python, or Java are utilized.
• Adhering to rules is crucial during this phase.

Product Testing and Integration

• Software is thoroughly checked for errors after construction.
• Documentation (manual) is created to assist users.

Deployment and Maintenance of Products

• Software is released in parts, following a plan.
• Real-world performance is assessed.
• Post-release monitoring ensures proper functioning and improvements are made based on feedback.

Software Development Models

• Various processes and methods are selected based on project objectives and goals.
• Development life cycle models achieve objectives and specify process steps/ their order.

Plan-Driven and Agile Processes

• Plan-driven processes involve advance planning of activities and progress measured against the plan.
• Agile processes use incremental planning to easily adapt to changing customer needs.
• Practical processes often blend plan-driven and agile approaches.

Plan Driven and Agile Processes

• The Waterfall Model
• Incremental Development
• Reuse-Oriented Software Engineering

Waterfall Model

• The Waterfall Model: a plan-driven model with separate phases for specification and development.
• Each phase must be completed before the next begins, with no overlapping.

Waterfall Model Advantages

• It is simple and easy to understand, with a straightforward sequential approach.
• Phases are well-defined, with specific goals.
• It has clear milestones that provide checkpoints for monitoring progress.
• Works well with large systems that has stable project requirements.

Waterfall Model Disadvantages

• Difficult to make changes once a phase is completed, making it inflexible to change
• There is limited client input mainly at the beginning and end, restricting feedback.
• The sequential nature may result in a longer time to deliver a functional product, and thus, a long delivery time.
• It may not adapt well to uncertain or changing requirements.

Incremental Development

• This approach includes specification, development, and validation activities.
• The system is developed in versions (increments), each adding to the previous.
• It may be plan-driven or agile.

Reuse-Oriented Software Engineering

• The system is assembled from existing components.
• System development focuses on integrating these components into a system instead of developing them from scratch.
• May be plan-driven or agile.

Agile SDLC Models (Software Development Models)

• Agile Development Model uses sprints lasting 1-4 weeks with daily scrums.
• Sprints have retrospective meetings and planning sessions for each product backlog, sprint backlog, implementation, and review to create a completed product.