Software Development Life Cycle Models: A Comprehensive Guide

Posted on Nov 2, 2024 in Other subjects

Software Development Life Cycle Models

Classic Life Cycle

The systems development life cycle (SDLC) involves activities performed by analysts, designers, and users to develop and implement information systems. The SDLC consists of six phases:

  1. Preliminary Investigation: A system request starts with a user’s need, which triggers the process.
  2. System Requirements Determination: Understanding all facets of the business under study is crucial in systems analysis.
  3. System Design: This phase details how the system will meet the identified requirements. It includes logical design (defining system functionality) and physical design (creating the actual software).
  4. Software Development: Software can be developed in-house, outsourced, or purchased off-the-shelf, depending on cost, time, and resources.
  5. System Testing: Rigorous testing ensures the software operates as specified and meets user expectations.
  6. Implementation and Evaluation: This phase involves installing hardware, training users, deploying the application, and setting up data files. Post-implementation, the system is evaluated for strengths and weaknesses across operational, organizational, and developmental dimensions.

Prototyping Model

Prototypes offer a preliminary view of the system. Used early in the SDLC, they help gather user feedback and refine system requirements. Types of prototypes include:

  • Patching Prototype: A functional but basic system slated for later improvement.
  • Non-operating Prototype: A scale model used to test specific design aspects, often focusing on input and output interfaces.
  • First of a Series Prototype: A full-scale pilot system useful for multiple installations.
  • Selected Features Prototype: A working model with some, but not all, final system features, built in modules for easier integration.

Developing a Prototype

Guidelines for prototype development:

  1. Manageable Modules: Focus on key features in separate modules.
  2. Rapid Construction: Use readily available tools for quick development.
  3. Amendments: Design for flexibility and iterative changes based on user feedback.
  4. User Interface Emphasis: Prioritize an intuitive and user-friendly interface.

Advantages of Prototyping: Early system changes, potential to stop dysfunctional systems, and better understanding of user needs.

Disadvantages of Prototyping: Difficult project management and potential user confusion between prototype and final system.

Rapid Application Development (RAD)

RAD is a linear sequential model emphasizing a short development cycle and component-based construction. Steps include:

  1. Business Modeling: Analyze information flow between business functions.
  2. Data Modeling: Refine information flow into data objects with attributes and relationships.
  3. Process Modeling: Transform data objects into process descriptions for adding, editing, deleting, and retrieving data.
  4. Application Generation: Utilize fourth-generation techniques and reuse existing components.
  5. Testing and Delivery: Focus on testing new components and interfaces.

Evolutionary Process Models

Incremental Model

This model combines linear sequential development with prototyping. Each iteration delivers a functional increment, starting with a core product and adding features until completion. It’s beneficial for smaller teams and managing technical risks.

Advantages: Reduced initial development time, early delivery, user involvement, and easier change accommodation.

Disadvantages: Not suitable for high-risk or complex systems, requires careful planning, and potential for late error detection.

Component Assembly Model

This model assembles applications from pre-built components (classes). It involves identifying, reusing, and building components, leading to significant time and cost savings.

Concurrent Development Model

This model allows concurrent execution of software development phases, often used in client/server development. It provides an accurate project status overview.

Unified Modeling Language (UML)

UML is a standardized modeling language for specifying, visualizing, constructing, and documenting system artifacts. It’s tool-supported, extensible, and applicable to various systems and domains.

Component Assembly and Formal Methods

This model leverages reusable components, simplifying testing, maintenance, and improving quality. It involves identifying, reusing, and building components, leading to significant time and cost savings.

Spiral Model

This model combines the classic life cycle with prototyping and risk analysis. Each iteration involves customer communication, planning, risk analysis, engineering, construction, and customer evaluation. It’s suitable for evolving products but can be time-consuming and expensive.

Advantages: Reduced project risk, focus on quality, and integration of development and maintenance.

Disadvantages: Long development time, high cost, and requires risk assessment expertise.