Incremental build model

The incremental build model is a method of software development where the model is designed, implemented and tested incrementally (a little more is added each time) until the product is finished. It involves both development and maintenance. The product is defined as finished when it satisfies all of its requirements. This model combines the elements of the waterfall model with the iterative philosophy of prototyping.

The product is decomposed into a number of components, each of which are designed and built separately (termed as builds). Each component is delivered to the client when it is complete. This allows partial utilisation of product and avoids a long development time. It also creates a large initial capital outlay with the subsequent long wait avoided. This model of development also helps ease the traumatic effect of introducing completely new system all at once. There are, overall, few problems with this model.

Incremental Process Models

The initial software requirements may be well-defined but it provides a limited scope of development, in such cases expansion is required and a process model is designed .

Incremental Model

The incremental Model is an evolution of the waterfall model, where the waterfall model is incrementally applied.

The series of releases is referred to as “increments”, with each increment providing more functionality to the customers. After the first increment, a core product is delivered, which can already be used by the customer. Based on customer feedback, a plan is developed for the next increments, and modifications are made accordingly. This process continues, with increments being delivered until the complete product is delivered. The incremental philosophy is also used in the agile process model(see Agile Modeling).

Advantages

1. After every iteration any faulty piece software can be identified easily as very few changes are done after every iteration.
2. It is easier to test and debug as testing and debugging can be performed after each iteration.
3. This model does not affect anyone's business values because they provide core of the software which customer needs,which will indeed help that person to keep run his business.
4. After establishing an overall architecture,system is developed and delivered in increments.

Disadvantages

1. If the requirements intially were thought to be stable but at later stages are realized to be unstable then the increments have to be withdrawn and have to be reworked.
2. Resulting cost may exceed the cost of the organization.
3. Problems may arise related to system architecture.

RAD model

Rapid Application Development (RAD) is an incremental software process model that emphasizes a short development. A component based construction approach is used. A RAD process development team can create a “fully functional system” within a very short time period provided that the requirements are clearly communicated. The generic framework activities are presented earlier.

Tasks involved

These tasks are common to all the models

1. Communication: helps to understand the objective.
2. Planning: required as many people (software teams) work on the same project but different function at same time.
3. Modelling: involves-business modeling,data modeling,process modeling and process modeling.
4. Construction: this involves the reuse software components and automatic code
5. Deployment: integration of all the increments

References

• Software engineering A Practitioner's Approach-by Roger S. Pressman(McGraw-Hill International Edition)

External links

1. http.myprojects.kostigoff.net/methodology/development_models/development_models.htm
2. www.softdevteam.com/Incremental-lifecycle.asp

See Iterative and incremental development