Boehm has proposed the spiral model .Spiral models software process is combination of an iterative nature of prototyping and controlled and systematic aspects of the traditional waterfall model. This model is able to produce rapid development in more complicated version of software.
IN SPIRAL MODEL, software development takes place in a series of developed releases. In initial stage iterations, the release or model might be presented on a paper or may be a prototype model. These are kind of designing stages. In the later stages when completing stages comes software system is actually produced.
Fig 1.3 spiral model phases
A spiral model is made up of set of different framework activities made the software engineering. For example generic framework activities discussed in last sections Every framework activities represent one section of the spiral path .As the development process starts; the software team performs activities that are indirect by a path around the spiral model and i.e. Risk.
The effect of the staring route around the spiral might is in the development of a product specification following passes around the spiral might be used to develop a prototype and then more sophisticated versions of the software. After development gents over; the product is delivered to the customer. The main factors cost and schedules are adjusted depending on feedback received from the customer. The project manager adjusts the number of iterations or repetitions which are planned earlier required for the software.
The main feature of spiral model is that it can be used to apply throughout the computer software’s life. The first circuit or loop around the spiral may represent “concept development project “which begins at the centre of the spiral model. It continues and makes multiple iterations till concept development get complete. The spiral model is used to develop large scale projects. As the software development takes place the customer as well and development teams understand the requirement s and the risks involved in the project.
Prototyping is used for risk reduction in spiral model .the reason behind this is prototyping can be used by developers at any point of time. Spiral model maintains the systematic stepwise approach used by developers at any time that I more practical which is applicable to real world. Though there are many unique features of spiral model but it is a final solution.
There is certain disadvantage of this model as listed below
1. Convince customers for evolutionary approach is difficult
2. Expert people are required for evaluation of risks
3. in case if there are major risks which are not covered and managed the problem will occur through the project.