Navigating the Software Development Lifecycle (SDLC): A Comprehensive Guide

Software Development Lifecycle (SDLC)

The Software Development Lifecycle (SDLC) is a structured methodology used in software engineering to guide the process of designing, creating, testing, and deploying software applications. It’s essentially a framework that outlines the various stages and activities involved in the development of software, from its conception to its delivery and maintenance.

History of Software Development Lifecycle (SDLC)

The history of the Software Development Lifecycle (SDLC) dates back to the early stages of modern computing. The evolution of the SDLC is marked by various methodologies and practices that have shaped how software is developed, managed, and deployed. Here’s an overview of its historical progression:

Early Software Development Practices (1950s – 1960s):

  • During the early days of computing, software development lacked a formalized process.
  • Projects were often ad-hoc, with developers creating programs without a structured approach.

Waterfall Model (1970s):

  • The Waterfall model is one of the earliest structured methodologies. It introduced a linear and sequential approach to software development.
  • Developed by Winston W. Royce in 1970, it outlined distinct phases (requirements, design, implementation, testing, deployment, maintenance) that had to be completed before moving to the next stage.
  • Despite its rigidity, the Waterfall model provided a structured framework for development.

Iterative and Incremental Development (1980s – 1990s):

  • Iterative approaches emerged, emphasizing repetitive development cycles, and allowing for incremental improvements and adjustments.
  • This period saw the rise of methodologies like Rapid Application Development (RAD), where quick prototyping and iterative development were emphasized.

Agile Manifesto (2001):

  • Agile methodologies came to prominence with the publication of the Agile Manifesto in 2001.
  • This marked a shift from rigid, document-heavy processes to more adaptive, collaborative approaches.
  • Agile prioritized individuals and interactions over processes and tools, customer collaboration, responding to change, and working software over comprehensive documentation.

Various Agile Methodologies (2000s – Present):

  • Scrum, one of the most popular Agile methodologies, introduced short, time-boxed development cycles called sprints.
  • Kanban, another Agile approach, emphasizes visualizing work and optimizing flow.
  • DevOps emerged as a philosophy emphasizing collaboration between development and operations teams to automate processes and shorten the software delivery lifecycle.

Continuous Improvement and Specialized Models:

  • The software development landscape continues to evolve with a focus on continuous improvement, automation, and specialized models catering to specific aspects of development.
  • Hybrid models combining Agile principles with traditional approaches have gained traction, adapting to various project needs.

The history of the SDLC reflects the industry’s journey towards adopting more flexible, collaborative, and iterative approaches to software development. It’s been shaped by the need to manage complexity, adapt to changing requirements, and deliver high-quality software efficiently. The evolution continues as new technologies and methodologies emerge, influencing how software is developed and delivered.

Stages/Phases in Software Development Lifecycle (SDLC)

  1. Requirement/Information Gathering
  2. Analysis
  3. Design
  4. Coding/Implementation
  5. Testing
  6. Maintenance

Phases in Software Development Lifecycle (SDLC)

1. Information/Requirement Gathering

  • A business Analyst (BA) is responsible for information gathering.
  • It is a requirement gathering from customers or Clients.
  • Information gathering involves business requirement specification (BRS) which is prepared by a Business Analyst (BA).
  • Business requirement specification (BRS) is the bridge between the client and the team.

Business requirement specification (BRS)

Gather requirement example: Banking project

  • Sign up page
  • Home page
  • Account info page
  • Contact page etc.

This is an overall requirement for gathering

2. Analysis

  • A business Analyst (BA) is involved in this process and here software requirement specification (SRS) document is made which is named Software/System Requirement Specification.
  • Software requirement specification (SRS) is made after Business requirement specification (BRS).
  • Software requirement specification (SRS) is a detailed document.

Software requirement specification (SRS)

Example: Sign up page should have Name, Number, Email, Password, etc.

This is the detailed specification which shows minor units of software.

Software requirement specification (SRS) documents include:

  • Functional Flow Diagram.
  • A functional flow diagram means the flow of our task.
  • This shows the relationship between each task.
  • This gives a proper sequence of tasks.

Example: Facebook or any website

Functional Flow Diagram

The function flow diagram looks like the above diagram.

Overall, this functional flow diagram is a step-wise representation of software.

Functional Requirement

Functional Requirement means attributes that are required to complete a specific function.

Now we have a signup function.

For sign-up, its requirements are:

  •  First name
  •  Last name
  •  Mobile number
  •  Email
  •  Password
  •  Submit button

Now for the first name requirement is:

  • The name should be in characters.
  • The name should not have numbers.
  • It should not have spaces.
  • It should not have special characters.

All kinds of requirements are fulfilled in this phase.

Snapshot

  • It’s a visualization of the functionality before the development of the product.
  • It is created by a Business Analyst (BA).
  • This gives an idea to the developer as to how the software will look like.
  • Software requirement specification (SRS) sent to all stakeholders or teams.
  • When developers do coding, testers do test case design means writing test cases.

3. Design

  • Based on the requirements specified in Software requirement specification (SRS) a Design Document Specification (DDS) OR Technical Design Document (TDD) is proposed and documented.
  • Here, the Technical Design Document (TDD) is divided into two levels.

Types of Technical Design Documents (TDD)

  • High-Level Design (HLD)
  • Low-Level Design (LLD) 

High-Level Design

Low-Level Design

It contains the design of the working main
module.

It includes the static logic of the submodule.

It includes what and how any module does
work.

On sign up page, sign-up is the main module
and the rest fields like first name, last name,
email etc. are the sub-modules.

A design architect creates it

It is created by a front-end developer.

4. Implementation/Coding

  • Coding means programming.
  • One line of code is code.
  • Multiple lines of code are called programs.
  • A set of programs written by a developer creates software.

Types of Developers

  • Front-End Developer: The front-end developer develops UI, functionality, and process.
  • Back-End Developer: Data management, Data gathering, and Data security are done by the back-end developer.
  • Full Stack Developer: A developer who works as a front-end developer as well as back back-end developer is called a full stack developer.

5. Testing

  • Testing is the process of checking the completeness and correctness of the software.
  • Methods of Testing
  1. White Box Testing
  2. Black Box Testing
  3. Grey Box Testing

White Box Testing

  • White box testing is done by a coder because code knowledge is required.
  • It is also called code-level testing/unit testing/clear box testing.
  • In white box testing whenever the coder completes his code writing, he checks or compiles code then if any bug is found coder has to solve it.
  • The coder cannot send code to the tester without doing white box testing.
  • The coder checks or tests mostly positive scenarios only.
  • White box testing has the purpose of testing the correctness and completeness of the program.

Black Box Testing

  • Black box testing is known as system and function testing.
  • This testing is done by a tester.
  • Overall functionality gets checked in this type of testing.
  • Testers check internal functionality depending upon external functionality.

Example:

The tester checks whenever the data sign-up module is entered and users press the sign-up button, this button is processed to store the entered data. The tester checks whether the data is stored correctly or not.

So here internal functionality is storing data and external functionality is filling up data in fields and submitting buttons process.

  • The tester tests the positive and negative scenarios.
  • A positive scenario means if suppose we have a mobile number field with 10-digit functionality then as a tester we will check field functionality by entering a 10-digit number whether it works.
  • A negative scenario means if suppose we have a mobile number field with 10-digit functionality then as a tester if we check with 9 digits or less as it should not accept more than 10 digits.

Grey Box Testing

  • Grey box testing is a combination of both white box testing and black box testing.
  • To do grey box testing, the tester needs programming knowledge.
  • The role of the grey box tester is whenever the final software is handed over to the tester. The tester checks its functionality and if any fault occurs in the output of the function then the tester does not revert the system to the developer, Instead the tester himself solves or makes changes in the code. So knowledge of coding is required.

6. Deployment and Maintenance

  • Once the product is tested and ready to be deployed it is released formally in the appropriate market (on a production server). Sometimes product deployment happens in stages as per the organization, business strategy.
  • Maintenance means providing service after delivery (like bug improvement or enhancement) of the project.
  • After delivery of any bug or enhancement occurs then all come under maintenance.
  • Maintenance involves non-technical as well as technical support.
  • Non-technical support is called BPO.
  • Technical support is called KP.

Models in Software Development Lifecycle (SDLC)

There are several Software Development Lifecycle (SDLC) models, each offering a different approach to managing the development process. Here are some of the most common models:

  1. Waterfall Model:
    • Description: This model follows a linear and sequential approach. Each phase of the SDLC (requirements, design, implementation, testing, deployment, maintenance) is completed before moving to the next phase.
    • Advantages: Easy to understand and manage due to its linear nature. Well-suited for projects with clear and stable requirements.
    • Disadvantages: Less flexible, limited room for changes once a phase is completed. Client feedback was incorporated late in the process.
  2. Agile Methodology:
    • Description: Agile emphasizes flexibility, collaboration, and customer involvement throughout the development process. It promotes iterative development with short cycles called sprints.
    • Advantages: Highly adaptable to changes, encourages customer feedback, promotes continuous improvement, and faster delivery.
    • Disadvantages: May require a higher level of customer involvement, can be challenging to manage larger projects without proper organization.
  3. Scrum:
    • Description: A specific Agile methodology that operates in short iterations (sprints) with defined roles like Scrum Master and Product Owner. Daily meetings (stand-ups) keep teams aligned.
    • Advantages: Encourages teamwork, transparency, and adaptability. Helps in delivering incremental features.
    • Disadvantages: Can be challenging for less experienced teams. Requires a high level of collaboration and communication.
  4. Iterative Model:
    • Description: In this model, development is broken down into smaller segments or iterations. Each iteration goes through the phases of the SDLC, allowing for continuous refinement.
    • Advantages: Allows for early detection of issues, better adaptability to changes, and improved risk management.
    • Disadvantages: Potential for increased complexity with multiple iterations, and each iteration may require its own set of resources.
  5. DevOps:
    • Description: Focuses on collaboration between development and IT operations teams, aiming to automate the software delivery process and improve deployment frequency.
    • Advantages: Accelerates the delivery process, improves collaboration, and enhances overall quality.
    • Disadvantages: Requires cultural changes within organizations and may involve a steep learning curve for adopting new tools and practices.

These models offer different approaches to managing software development projects, and the choice of model often depends on project requirements, team dynamics, timelines, and the level of flexibility needed throughout the development process.

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