Software Development Models:
A software cycle deals with various parts and phases from planning to testing and deploying. All these activities are carried out in different ways, as per the needs. Each way is known as a Software Development Lifecycle Model (SDLC).
Software life cycle models describe phases of the software cycle and the order in which those phases are executed. There are lots of models, and many companies adopt their own, but all have very similar patterns.
The spiral model is similar to the incremental model, with more emphases placed on risk analysis. The spiral model has four phases:
- Risk Analysis
A software project repeatedly passes through these phases in iterations (called Spirals in this model). The baseline spiral, starting in the planning phase, requirements are gathered and risk is assessed. Each subsequent spirals builds on the baseline spiral.
Requirements are gathered during the planning phase. In the risk analysis phase, a process is undertaken to identify risk and alternate solutions. A prototype is produced at the end of the risk analysis phase.
Software is produced in the engineering phase, along with testing at the end of the phase. The evaluation phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral. In the spiral model, the angular component represents progress, and the radius of the spiral represents costs.
Advantages of the Spiral model
- A high amount of risk analysis is carried out hence the project becomes safe.
- Good for large and mission-critical projects.
- Software is produced early in the software life cycle.
- Defers elaboration of low-risk software elements.
- Incorporates prototyping as a risk reduction strategy
- Gives an early focus to reusable software.
- Accommodates life – cycle evolution, growth, and requirement changes.
- Incorporates software quality objectives into the product.
- Focus on early error detection and design flaws.
- Sets completion criteria for each project activity to answer the question: ” how much is enough?
- Uses identical approaches for development and maintenance.
- Can be used for hardware and software system development.
Disadvantages of the Spiral model
- Can be a costly model to use.
- Risk analysis requires highly specific expertise.
- Project ‘ s success is highly dependent on the risk analysis phase.
- Doesn’ t work well for smaller projects.