Software Development Life Cycle (SDLC)
The Software Development Life Cycle (SDLC) is a structured process used by the software industry to design, develop, and test high-quality software. It aims to produce high-quality software that meets or exceeds customer expectations, reaches completion within times and cost estimates.
1. The Phases of SDLC
The SDLC typically consists of the following stages:
1. Planning and Requirement Analysis
The most fundamental stage. Senior members perform requirement analysis with inputs from the customer, sales department, market surveys, and domain experts.
- Goal: Define what needs to be built and feasibility (technical, operational, economic).
2. Design
Based on requirements, the system architecture is defined. This is often documented in a Design Document Specification (DDS).
- High-Level Design (HLD): Architecture, database design, interface design.
- Low-Level Design (LLD): Detailed logic of modules, error handling.
3. Implementation (Coding)
The actual development starts here. Developers write code according to the design documents and coding standards.
- Goal: Translate design into executable code.
4. Testing
Code is tested against the requirements to ensure it solves the needs gathered during the planning phase.
- Types: Unit testing, Integration testing, System testing, Acceptance testing.
5. Deployment
Once tested, the software is deployed to the production environment. This might happen in stages (Alpha, Beta, Production).
6. Maintenance
After deployment, the software needs to be maintained.
- Bug Fixing: Fixing issues reported by users.
- Upgrade: Adding new features or upgrading to newer platforms.
2. Common SDLC Models
Waterfall Model
The classic, linear approach. You finish one phase completely before moving to the next.
- Pros: Simple, easy to manage.
- Cons: Inflexible. Changes are expensive once a phase is passed.
Agile Model
An iterative and incremental approach. The product is broken into small incremental builds.
- Pros: Flexible, faster delivery of features, high customer involvement.
- Cons: Documentation can get left behind, scope creep.
DevOps
Combines development (Dev) and operations (Ops) to shorten the systems development life cycle.
- Focus: Automation, CI/CD, monitoring.
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