Understanding the Systems Development Life Cycle (SDLC)
The Systems Development Life Cycle (SDLC)
The Systems Development Life Cycle (SDLC), also known as the Software Development Process in systems engineering, information systems, and software engineering, is a structured approach to creating or modifying information systems. It encompasses the models and methodologies used to develop these systems. In software engineering, the SDLC concept underpins various software development methodologies, providing a framework for planning and controlling the creation of information systems.[1]
The SDLC, employed by systems analysts, guides the development of information systems, including training and stakeholder ownership. A successful SDLC should result in a high-quality system that meets or exceeds customer expectations. It should also be completed within time and budget constraints, operate effectively within the current and planned IT infrastructure, and be maintainable and cost-effective to enhance.[2]
Addressing Complexity in System Development
Modern computer systems are complex, often integrating multiple traditional systems from different vendors, particularly with the rise of service-oriented architecture. To manage this complexity, several SDLC models or methodologies have emerged, each with its own approach:
- Waterfall: A linear, sequential model where each phase depends on the completion of the previous one.
- Spiral: An iterative model that emphasizes risk analysis and prototyping.
- Agile Software Development: Focuses on flexibility, collaboration, and iterative development with short cycles.
- Rapid Prototyping: Emphasizes creating prototypes to gather early feedback and refine requirements.
- Incremental: Develops the system in increments, with each increment adding functionality.
- Synchronize and Stabilize: Used for large-scale projects, involving parallel development and regular synchronization points.
These models can be categorized along a spectrum of Agile to Iterative to Sequential. Agile methodologies, such as XP and Scrum, prioritize lightweight processes and rapid changes. Iterative methodologies, like Rational Unified Process (RUP) and Dynamic Systems Development Method (DSDM), focus on limited scope and iterative improvements. Sequential models, such as Waterfall, emphasize comprehensive planning for large projects to achieve predictable results.[3]
SDLC vs. PLC
In project management, both the Project Life Cycle (PLC) and SDLC are used, each with a slightly different focus. According to Taylor (2004), “the project life cycle encompasses all the activities of the project, while the systems development life cycle focuses on realizing the product requirements”.[4] The SDLC specifically addresses the stages involved in developing an IT project, from conception to completion.
History of SDLC
The Systems Life Cycle (SLC) emerged in the 1960s to address the need for a structured approach to building large-scale business systems. This methodology aimed to develop information systems methodically, with each stage carefully planned and executed. As Elliott, Strachan, and Radford (2004) note, “Information systems activities revolved around heavy data processing and number crunching routines” during this era.[5]
The SDLC influenced the development of various system development frameworks, including the Structured Systems Analysis and Design Method (SSADM), created for the UK government in the 1980s. However, as Elliott (2004) points out, traditional SDLC approaches have been increasingly replaced by alternative frameworks that address some of their inherent limitations.[5]
Phases of the SDLC
The SDLC provides a sequence of activities for system designers and developers, ensuring a systematic approach to system development. Each phase builds upon the results of the previous one, ensuring a logical progression. While various SDLC models exist, they generally include the following key phases:[6]
1. Preliminary Analysis
- Conduct a preliminary analysis: Define the organization’s objectives and the problem’s nature and scope.
- Propose alternative solutions: Explore potential solutions through interviews, competitor analysis, and internal assessments.
- Describe costs and benefits: Analyze the costs and benefits of each proposed solution.
2. Systems Analysis and Requirements Definition
- Define project goals and translate them into specific system functions and operations.
- Analyze and document end-user information needs.
3. Systems Design
- Detail the desired system features and operations, including screen layouts, business rules, process diagrams, and pseudocode.
4. Development
- Write the actual code based on the design specifications.
5. Integration and Testing
- Combine all system components in a testing environment.
- Conduct thorough testing to identify and fix errors, bugs, and interoperability issues.
6. Acceptance, Installation, and Deployment
- Deploy the system into the production environment after successful testing and stakeholder acceptance.
7. Maintenance
- Manage the system throughout its operational life, including changes, corrections, additions, platform migrations, and ongoing support.
The SDLC ensures a structured and systematic approach to system development, increasing the likelihood of delivering successful information systems that meet user needs and business objectives.