Software Development Life Cycle is a step-by-step process of developing software applications. Software development life cycle involves complete structured process of planning, defining, designing building, testing and deployment of software. SDLC comprises of series of phases which ensure that the end product us quality and meet customer requirements.
Goal of software Development Life Cycle
The ultimate goal of software development life cycle is to produce high-quality software that can meet or even exceed the required expectations. The Software development life cycle ensures that the software is developed and deployed with the set timelines and fits within the cost estimates. The objective of SDLC is also to maintain the durability and maintenance of software for future adaptability.
How Does SDLC Works? (Stages of Software Development Life Cycle)
The Software Development Life Cycle is a systematic process for developing high-quality software. SDLC has seven well-defined stages and each stage has specific activities and deliverables to make sure that developed software is efficient and reliable.
Following are the stages of Software Development life cycle
- Planning
- Requirement Analysis
- Design
- Development
- Testing
- Deployment
- Maintenance
Planning
Objective: To define the objective of plan, scope and feasibility.
During planning phase, the project team including project manager, clients, and development team come together to understand the project goals. The team decides that if the goals is viable. The planning phase includes estimation of time, resources, money and personnel required for project. The output of the planning phase serves as roadmap for the entire process.
Key Activities:
- Requirement gatherings and defining objective of the plan.
- Project timeline and budget estimation.
- Feasibility to ensure the project is achievable.
Deliverables:
- Plan Project
- Feasibility Report
Requirement Analysis
Objective: To gather and define what the software needs to accomplish.
At this stage, the functional and non-functional requirements of the software are clearly documented. In this phase clients and stakeholders clearly share their needs with development team. This process provides a blueprint of the entire development process.
Key Activities:
- Collecting detailed user requirements
- Defining functional and non-functional requirements
- Documentation of the all requirements from software.
Deliverables:
- Software Requirement Specification
- Use Case Diagrams
Design
Objective: Transformation of requirements into detailed architecture and design of the software.
The design phase is where the software’s architecture is defined. Design phase determines the software and hardware components, database structure, and overall user interface of the software. In this phase designers and architectures create detailed specification that will guide developers in the coding phase.
Key Activities:
- Creating system architecture and design.
- Designing and database schema
- Breaking down the system into modules
Deliverables:
- High-level design document
- Low-level design document
- Database schema
- User interface mockups
Development
Objective: To write the code as per design specifications.
During Development phase the actual source code of the software is written. This process is done on the base of the design documents created in the previous phase. This work is divided into modules or units and developers start coding each module. This is the longest phase of software development life cycle.
Key Activities:
- Writing the source code for each module or component
- Implementing database, user interface and business logic
- Conducting code reviews to ensure quality
Deliverables:
- Source code
- Database scripts
- Code documentation
Testing
Objective: To ensure that the software works as expected and is free of defects.
In this phase of SDLC the developed software is tested to ensure that it meets the specified requirements and is free from mugs. Testing phase involves unit testing, integration testing, system testing and user acceptance testing. Automated testing tools or manual methods are also used sometime depending upon the project.
Key activities:
- Writing and executing test cases.
- Performing functional, non-functional, and testing.
- Identifying bus and defects and fixing them.
- Ensuring the software meets performance and security standards.
Deliverables:
- Test Plan
- Test Cases
- Test Report
- Bug Reports and Resolutions.
Deployment
Objective: To release the software to the production environment for users.
Once the testing phase is complete and the software is deemed stable and ready for use, it is deployed to a live environment. Deployment can be done in stages such as beta testing with a smaller user group or full-scale development.
Key activities:
- Deployment the software to the production environment
- Monitoring the system for issue after deployment.
- Migrating data, if necessary, from old system to the new system
- Training end users.
Maintenance
Objective: To provide regular updates and support to software for proper function and efficiency.
After deployment, the software enters the maintenance phase. In this stage of software development life cycle developers provide continuous support, fix bugs and implement enhancements and updates when required. This phase ensures that software adapts to the changing needs and technologies over time.
Key Activities:
- Fixing bugs and issues discovered after deployment.
- Improving software on the basis of feedback and requirements.
- Regularly updating the software to improve performance.
Deliverables:
- Software patches and updates
- System performance reports
- Documentation updates
Software Development Life Cycle Models
Software Development life cycle models are the reference framework models which help development team to plan, organize and structure software development projects. Depending upon the project requirements and needs development team choose the most suitable SDLC model. Following are most common software development life cycle models.
Waterfall Model
This is the earliest and most traditional models. In this model the development approach is very linear and sequential where each phase must be completed before the next begins.
Key Features: Sequential Model, no overlapping of steps, Document-driven approach, simple and easy to understand
Drawbacks: Little flexibility for changes and not suitable for complex projects.
SDLC and Agile Model
SDLC and Agile methodology is an iterative and incremental approach that focus on flexibility, collaboration and customer satisfaction. In SDLC agile method the project is split into small units called sprints which is of 1-4 weeks, with involvement of feedback and improvements.
Key features: Iterative development with continuous feedback and flexibility.
Drawbacks: Less comprehension in documentation than traditional models, strong communication requirements.
V-Model
V-model is the integration of waterfall model with more emphasize on validation and verification at each stage. This model is more like a testing model with proper testing of each development at every stage.
Key Features: Verification and validation, development with proper testing and quality assurance.
Drawbacks: Not suitable with dynamic requirements and less flexibility.
Iterative Model
Iterative model develops software in repeated cycles. Once a version of software is developed then it is tested through repetition of tests. Iterative model builds the software in step by steps increments.
Key features: Cyclic process, feedback driven and progressive development.
Drawbacks: this model requires accurate planning; integration can be complex as new features are added in each iteration.
Spiral Model
Spiral models are a combination of waterfall model with iterative model. This model is a risk-driven approach and is useful for large, high-risk projects where on-going risk management is crucial.
Key Features: Risk Analysis, Iterative Process and Customer Involvement
Disadvantages: Expensive model and Complex to manage.
Big Bang Model
Big Bang Model is less complex and simple structured model. This model starts with minimal initial planning. Developers can develop the software without much needed documentation.
Key Features: Minimal Planning requirements.
Drawbacks: High risk of project failure and no structured process.
DevOps Model
This model combines development and operations team to enable continuous integration and continuous delivery. It is closely related to Agile but focuses heavily on collaboration between developers and IT operations.
Key Features: Continuous Integration and Delivery and Automation.
Drawback: Requires strong communication between teams.
How Does Software Development Life Cycle Address Security?
SDLC addresses the security through DevSecOps, an extension of the traditional DevOps model. This latest extension has integrated security practice in every step of the software development life cycle. In this latest approach of SDLC security is treated as a shared responsibility across developments, operations, and security teams, ensuring that software is secure from initial design to deployment and further in maintenance.
SDLC addresses Security in
Planning Phase: security requirements are considered from very beginning. By identifying potential risks, security measures are defined which prevents the major rework later in the development cycle.
Gathering Phase: Through DevSecOps SDLC embeds security requirements in the development process ensuring that applications meet the necessary security standards.
Security in Design Phase: Security principles like least privileged and defense in depth are applied in design phase. Security Activities like threat modeling, secure design patterns and security architecture review are properly designed and integrated in design phase.
Security in the Development phase: developers follow secure coding practices while writing codes. Developers use Code scanning tools and follow secure coding guidelines to identify and fix vulnerabilities during the coding process in the development phase.
Security in the Testing Phase: SDLC applies automated and manual security testing through DevSecOps ensure proper functioning of software. Dynamic Application Security Testing, Penetration Testing and Security Regression Testing are applied to prevent security issues.
Security in the Deployment Phase: includes Configuration management, infrastructure as Code Security and continuous monitoring to ensure that software is properly deployed.
Security in the Maintenance: This is the last phase of SDLC and security in this phase includes Patch management and incident response plan to avoid security breaches after deployment.
Software Development Life Cycle Policy
Software Development life cycle policy refers to policy which decides the standards, procedures, and guidelines for development, maintenance, implementation of a software within an organization. SDLC policy is a final document and is very essential for reducing risks, improving productivity and ensuring that software is secure and functional throughout its life cycle.
Purpose of SDLC Policy: Purpose of the SDLC policy is to clarify the requirements from company managers, business project managers, technical project managers and other stakeholders in successful planning and deployment of software.
Scope of SDLC Policy: Software Development life cycle policy is applicable to all software development projects whether internal or external. The policy is applicable to all team involves in the project lifecycle. SDLC policy is applicable to new software development, its updates and maintenance.
SDLC Policy Sample: You can check the SDLC policy Sample1 for reference.
SDLC Vs STLC
SDLC (Software Development life cycle) and STLC (software Development testing cycle) are two different cycles that play important roles in overall software development process. As the name indicates Software development life cycle is related to entire process of software planning to deployment, while Software development testing specifically focuses on testing phase.
Software Development life Cycle Vs Software Development Testing life cycle.
| Aspect | SDLC | STLC |
| Definition | SDLC is the process involving the development of software from planning to deployment and maintenance. | STLC is a series of systemic steps that focus on testing the software to ensure quality. |
| Phases Involved | Planning Requirement Analysis Design Development Testing Deployment Maintenance | Requirement Analysis Test Planning Test Case Development Test Environment Setup Text Execution Test Closure |
| Objective | To guide the complete process of software creation within set timelines and budgets. | To ensure that software is bug-free, and to deliver high-quality tested product. |
| Scope | SDLC applies from initial conception to post launch and to every team member involved in cycle. | STLC is confined to testing phase of software development. It begins once the software module is ready. |
| Team Involved | SDLC involves multiple teams including business analyst, developers, project managers, security specialists, testers and stakeholders | Primarily involves quality assurance or testing team. |
SDLC Documentation
Documentation in SDLC life Cycle refers to a comprehensive set of documents which are created and maintained throughout the software development life cycle. SDLC documentation serves as a roadmap and reference for everyone involved in the development cycle.
SDLC Planning Documentation
SDLC documentation in planning involves documentation of project proposal, feasibility study and overall project plan.
Requirements Documentation: documentation in business requirements and software requirements.
Design Documents: involves system design documents, high-level design documentation and low-level design documentations.
Development Documentation: involves source code documentation and version control documentation.
Testing Documentation: involves documentations of test plan, contents, test results and defect issue documentation.
Deployment Documentation: involves documentation of deployments and Release notes.
Maintenance and Support Documentation: documentation of usar manual, technical support and maintenance documentation.
Security Documentation: documentation of security requirements and risk assessment and mitigation plan.
Audit and Compliance documentation: documentation of regulatory and compliance standards.
References:
- https://comply-netlify-cms.netlify.app/documents/Sample-SDLCP.pdf ↩︎