Software Development Life Cycle Models
Evolutionary Prototyping Model
Description
It refers to the activity of creating prototypes of
software applications, for example, incomplete versions of the software
program being developed. It is an activity that can occur in software
development. It used to visualize some component of the software to
limit the gap of misunderstanding the customer requirements by the
development team. This also will reduce the iterations may occur in
waterfall approach and hard to be implemented due to inflexibility of
the waterfall approach. So, when the final prototype is developed, the
requirement is considered to be frozen.
It has some types, such as:
· Throwaway prototyping: Prototypes that are eventually discarded rather than becoming a part of the finally delivered software
· Extreme prototyping: used at web applications
mainly. Basically, it breaks down web development into three phases,
each one based on the preceding one. The first phase is a static
prototype that consists mainly of HTML pages. In the second phase, the
screens are programmed and fully functional using a simulated services
layer. In the third phase the services are implemented
The usage
· This process can be used with any software
developing life cycle model. While this shall be focused with systems
needs more user interactions. So, the system do not have user
interactions, such as, system does some calculations shall not have
prototypes.
| Advantages | Disadvantages |
| · Reduced time and costs, but this can be disadvantage if the developer lose time in developing the prototypes · Improved and increased user involvement | · Insufficient analysis · User confusion of prototype and finished system · Developer misunderstanding of user objectives · Excessive development time of the prototype · Expense of implementing prototyping |
Spiral Method (SDM)
Description
It is combining elements of both design and
prototyping-in-stages, in an effort to combine advantages of top-down
and bottom-up concepts. This model of development combines the features
of the prototyping model and the waterfall model. The spiral model is
favored for large, expensive, and complicated projects. This model uses
many of the same phases as the waterfall model, in essentially the same
order, separated by planning, risk assessment, and the building of
prototypes and simulations.
The usage
It is used in shrink-wrap application and large system which built-in small phases or segments.Advantages and Disadvantages
| Advantages | Disadvantages |
| · Estimates (i.e. budget, schedule, etc.) become more realistic as work progresses, because important issues are discovered earlier .· Early involvement of developers · Manages risks and develops system into phases | · High cost and time to reach the final product. · Needs special skills to evaluate the risks and assumptions · Highly customized limiting re-usability |
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