System Development Models

In this blog, we are about to discuss different system development models, their advantages and disadvantages. Before continuing to the topic if you don’t know or want to know about topics (Information System, Types of Information System, System Analyst, and System Development Life Cycle) then you can learn by visiting the links below.


System development models (also known as a software development methodology) are splitting of software development work into distinct phases (or stages) containing activities with the intent of better planning and management. It is often considered a subset of the systems development life cycle. The methodology may include the pre-definition of specific deliverables and artifacts that are created and completed by a project team to develop or maintain an application.
It is an abstract form of designing in which the description of the purposed system is developed. It is a conceptual tool that is used to create step-by-step solutions to the problem. In software development, there are various models that are used to create the software. Some of popular software development models are:
  • Waterfall model
  • Prototyping model
  • Spiral model
System Development Models (Methodologies) || Waterfall, Prototyping and Spiral models.

Waterfall Model or Linear Sequential Model

The waterfall model is a sequential design process, used in software development processes, in which progress is seen as flowing steadily downwards (like a waterfall) through the phases of conception, initiation, analysis, design, construction, testing, production/ implementation, and maintenance. This is the simplest approach to develop a new system. It is an old fashion but reasonable approach which is adopted when the requirements are completely or mostly known. This approach consists of the following phases:
  • Requirements
  • Analysis
  • Design
  • Implementation
  • Testing
  • Deployment
  • Maintenance

Diagram of Waterfall model

Diagram of Waterfall model

Advantages of Waterfall model

  • This model is simple and easy to understand and use.
  • It is easy to manage due to the rigidity of the model – each phase has specific deliverables and a review process.
  • In this model, phases are processed and completed one at a time. Phases do not overlap.
  • The waterfall model works well for smaller projects where requirements are very well understood.

Disadvantages of waterfall model

  • Once an application is in the testing stage, it is very difficult to go back and change something that was not well-thought-out in the concept stage.
  • No working software is produced until late during the life cycle.
  • High amounts of risk and uncertainty.
  • Not a good model for complex and object-oriented projects.

The Prototyping Model

Prototyping is a working model which is based on the interaction between analyst and user. It is developed on the basis of preliminary information gives the idea of how the full software will look likes and what it would perform? The user evaluates the prototype and refines the requirements to develop the full system. It is an attractive model to generate ideas for very large systems where there is no manual system. The prototype is helpful to obtain the details of the requirements from the user.

Diagram of Prototype model

Diagram of Prototype model

Advantages of Prototype model

  • Users are actively involved in the development.
  • Since in this methodology a working model of the system is provided, the users get a better understanding of the system being developed.
  • Errors can be detected much earlier.
  • Quicker user feedback is available leading to better solutions.

Disadvantages of Prototype model

  • This leads to implementing and then repairing way of building systems.
  • Practically, this methodology may increase the complexity of this system as the scope of the system may expand beyond original plans.
  • An incomplete application may cause the application not to be used as the full system was designed Incomplete or inadequate problem analysis.

The Spiral Model

The spiral model is similar to the incremental model, with more emphasis placed on risk analysis. The spiral model has four phases: Planning, Risk Analysis, Engineering, and Evaluation. A software project repeatedly passes through these phases in iterations (called Spirals in this model). In the baseline spiral, starting in the planning phase, requirements are gathered and risk is assessed. Each subsequent spiral builds on the baseline spiral. It is a risk-driven process model generator for software projects. Based on the unique risk patterns of a given project, the spiral model guides a team to adopt elements of one or more process models, such as incremental, waterfall, or evolutionary prototyping.

Diagram of the Spiral model

Diagram of the Spiral model

Advantages of Spiral model

  • The high amount of risk analysis hence, avoidance of Risk is enhanced.
  • Good for large and mission-critical projects.
  • Strong approval and documentation control.
  • Additional functionality can be added at a later date.
  • Software is produced early in the software life cycle.

Disadvantages of the Spiral model

  • Can be a costly model to use.
  • Risk analysis requires highly specific expertise.
  • The project’s success is highly dependent on the risk analysis phase.

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