Software Development Life Cycle (SDLC)

Software Development Life Cycle

• A systematic process for building quality and correct software.
• High-quality software produced should meet customer expectations.
• System development must be completed within a pre-defined time frame and cost.
• A detailed plan is required to plan, build, and maintain specific software.
• Every phase has its own process and deliverables that feed into the next phase.

Why Use SDLC?

• Provides a foundation for project planning, scheduling, and estimation.
• It delivers standard activities and project deliverables.
• Functions as a mechanism for project tracking and control.
• Increases and enhances development speed, while improving client relations.
• Helps reduce project risk and project management plan overhead.

SDLC Phases

• Requirement collection and analysis is the first phase.
• Feasibility study is the second phase.
• Design is the third phase.
• Coding is the fourth phase.
• Testing is the fifth phase.
• Installation/Deployment is the sixth phase.
• Maintenance is the seventh phase.

Phase 1: Requirement Collection and Analysis

• The software development team works to carry on the project.
• Discussions are held with stakeholders to gather as much information as possible on the project requirements.
• Requirements are planned into user, system, and functional requirements.
• Collected using:
  • Studying existing or obsolete systems and software.
  • Conducting user interviews.
  • Referring to databases.
  • Collecting answers from questionnaires.

Phase 2: Feasibility Study

• Assesses the viability of a project, ensuring it is legally, technically, and economically feasible.
• Determines if a project is worth the effort.
• Five types of feasibility checks:
  • Economic: Can the project be completed within budget?
  • Legal: Can the project be handled under cyber law and regulations?
  • Operational: Assesses how well the proposed system solves problems.
  • Technical: Checks if the current computer system can support the software.
  • Schedule: Decides if the project can be completed within the schedule.

Phase 3: Design

• Defines the architecture, modules, interfaces, and data for a system to satisfy requirements.
• Details can include screen designs, databases, sketches, system interfaces, flow-charts, and prototypes, depending on the project.
• Includes assessment and planning for security risks.

Phase 4: Coding

• Developers build the system by writing code using a chosen programming language.
• Tasks are divided into units or modules and assigned to developers, making it the longest phase.
• Developers must follow predefined coding guidelines and use programming tools like compilers, interpreters, and debuggers.

Phase 5: Testing

• The testing team tests the system's functionality to verify it meets customer requirements.
• The QA and testing team finds bugs/defects that are communicated to developers.
• The development team fixes the bug and sends back to QA for a re-test.
• Process continues until the software is bug-free, stable, and working according to the business needs.
• Consists of three testing activities:
  • α testing: System testing by the development team.
  • β testing: System testing by a friendly set of customers.
  • Acceptance testing: System testing by the customer after product delivery to determine whether to accept or reject the product.

Phase 6: Installation/Deployment

• The final deployment starts once software testing is over, and no bugs or errors are left.
• The final software is released and checked for deployment issues based on project manager feedback.

Phase 7: Maintenance

• Occurs once the system is deployed and customers start using it.
• Three activities:
  • Bug fixing: Addressing bugs reported from scenarios not tested previously.
  • Upgrade: Upgrading the application to newer software versions.
  • Enhancement: Adding new features to the existing software.
• Ensure needs continue to be met and the system performs as specified in the first phase.