prescriptive process models

 prescriptive process model orderly approach to software engineering. its specific step by step sequence of activities addressing how to do the software development. all activities involve the dependent on one or other activity.

1 . THE WATERFALL MODEL :

It is also referred as "traditional" or "typical" or "classic life cycle" . model an is the oldest model of the software engineering. This model was proposed by Winston Royce in 1970.

Different phases and activities performed in each phase of waterfall model.

waterfall model follows the generic framework activities in sequential manner. The developer completes each phase before moving to the next . As the diagram resembled cascading waterfalls this model in called as "waterfall model".

PHSES OF WATERFALL MODEL :

1. Communication and requirement analysis phase : understanding user requirement and documenting the it is the basic aim of the phase.

2. Planning and scheduling phase : This phase aims to schedule the various activities of software development it identifies the risk involve and estimate the cost of development. it is also helps in tracking the development. 

3. Modeling and design phase : The main goal of this phase is to design the overall system with detailed specification. 

4. Construction or coding and testing : As the name of suggest this phase is responsible for implementation of the system design.  various components of the system are coded and tested of ensuring accuracy . 

5. deploying or operating maintenance phase : The phase aims of maintenance and successful operation of development software at users end for final acceptance. 

FEATURES OF WATERFALL MODEL:

1. The entire development process is divided in to number of phase.

2. It uses a linear process flow.

3. Each phase perform a specific task or activity.

4. Each phase generates a certain outcome called as a "work product ".

5.Outcomes of previous page acts as a input for the next stage. 

ADVANTAGES OF WATERFALL MODEL :

1. It is very simple to understand and use.

2.As each stage is responsible for a specific task it helps in good scheduling as cost estimation.

3. Efficient use of resource because of good scheduling. 

4. Work product helps in the judging the progress of the development process. 

LIMITATIONS OF WATERFALL MODEL :

1.Software product rarely follow the sequential process.

2. IT is not easy for user to explicitly specify all requirement of the beginning of the project which the model expects. 

3. It is unable to ideal with uncertainty which exists at beginning off the project. 

4. when project enter in a later stage i e. coding and testing it becomes difficult to accommodate change.

5. If a problem is identified in later stage then rectifying the problem leads to increase in cost and time of development.

2. V- MODEL :

This model is also referred as Verification and validation model. basic phase performed for software development in v- model are same as waterfall model. this model considered at as extension to the waterfall model. In this model action be be carried out for ensuring the quality development are describe with with each fundamental phase of waterfall model. This action involve various tests do validate the product at which as shown in the below figure.

VALIDATION PHASES IN V- MODEL :

1. Unit testing : unit test are designed and performed to ensure error free code at program module level. It checks the correct execution of each functionality implemented. 

2.Integration testing: system testing and ensure the error free and smooth working of various component module together. 

3. System Testing : System testing ensures that the system that whole working and correctly and providing the expected functionalities. 

4. Acceptance testing :The system tested in user environment  before the final acceptance. 

ADVANTAGE OF V- MODEL :

1. testing is planned before planned well before coding.

2. higher chances for success over waterfall model. 

3.Efficient for small project when requirement are clearly specified. 

DISADVANTAGE OF V- MODEL :

1. Not flexible.

2. Does not work efficiently with large and complex project. 

3. Difficult to adapt to changing requirement. 

 

THE UNIFIELD PROCESS MODEL :

The unified process model tries to extract the best of all traditional model. The process flow in unified process is incremental iterative and highly focused. on customer involvement . It is mainly designed for object oriented developing using UML (Unified Modeling Language).

PHASES OF UNIFIED PROCESS ARE AS FOLLOWS :

Inception Phase :  Inception phase mainly focused on objectives, business requirement and scope of project. It involves communication and planning activities.

Elaboration phase :  At the end of this phase most of requirement of the system is identified .It involves communication and modeling activities. 

Construction phase : This phase results in the actual software increment. different software components are integrated together and software increment is developed and tested.  Analysis and design models developed in elaboration are thus completed here.

Transition phase :  The outcome of this phase results is product release. Here the developed software is transferred for beta testing to client environment. All supporting document like user manual installation procedure etc. are also delivered to the client together with the software.