Software Models

Models

Models are just a pictorial representation of logical conception which we are planning to deliver and try to implement the solution for a problem. Pictorial representation comprises of any working simulator / diagram and any mock drill.

Models play very vital roles in software development life cycle. We can say them backbone for development file cycle.

Exemplify some models:

-          Water Fall Model

-          V Model

-          Iterative and Incremental Model

-          Spiral Model

Now take them one by one

Water Fall Model: The first formal description was given by WISTON W. ROYCE in 1970. As per model all Development activities are carried out in sequence order. It is one of the oldest models for development. As name suggest water fall from high end to lower end same of that all the development activities is running out from high end to low end. In this model all the requirements are get freeze and then Development work get start. As development work finishes then deployment work start after that the developed application is hand over to Testing department. If all goes well then QC/ Testing team will hand over the developed application to client. If not then developed code / Application is handed over to Developed team to rework it on and enhance the code/application. This process goes until and unless QC team will give the clearance on developed code.

Than developed application under goes into Maintenance mode.

Advantages of waterfall model:

-          Simple to use and easy to understand.

-          Easy to manage-All the requirements are freeze and no changes into requirement so easy to implement no rework is

 Disadvantages of waterfall model:

-          Any requirement gets change it is very hard to update the code and test the change in requirement

-          Testing activity involve very late in Software development life cycle, that why is hard to fix the bugs in application .

-          This model not suits for real life application

-          Project and product risk is not taken care into this model.

V Model:  Verification and validation V model comes with solution for the challenges of traditional water fall model. Name of V model is Verification and Validation model. It was first introduce in Late 1980.this model testing activities is carried out simultaneously. All the issues related of the every stage is easily recorded and fixed in on regularly basis. Fixing of issues on regular basis will low down the costing of fixing of bugs and reduce rework.

Verification: It is a static type of testing, in that without executing the application code we have to find out the issues. Review process is part of the Verification process.

Validation: It is dynamic type of testing, in that we execute the code and find out the issues in the code. Black box testing is example of Validation process

                                        

Advantages

-          By involving testing at early stages , it will reduce the cost of rework.

-          By Involving both Static and Dynamic type of testing in model it will increase the Quality bug count and improve the overall quality of build product.

-          It provide all to overcome from water fall model.

Limits

-          To keep eye on bugs and changes, much documentation Is required.

-          The V-Model addresses software development within a project rather than a whole organization.

-          In this model Maintenance is not involved.

Iterative and Incremental Development Model: In IID development model all development life cycle activities goes in sequential manner but these sequence are going on regular iteration or many cycle. Requirements were broken down into various sub sets of requirements. This breakage is based on the risk, priority, and need of end user. After that a prototype is made on basis of these requirements and gets it approved by customer. As the prototype gets approved by client the development activities get happening. As this prototype is passed from QC team testing then it will delivered to client and user. IID model is created to overcome from the all the disadvantages of water fall development model.

             

Advantages of Iterative model:

-          In iterative model provide brief introduction about application in terms of basic idea of application .

-          All development activities go step by step.

-          In iterative model we can get the reliable user feedback. When presenting sketches and blueprints of the product to users for their feedback, we are effectively asking them to imagine how the product will work.

-          In iterative model less time is spent on documenting and more time is given for designing.

 Disadvantages of Iterative model: 

-          iteration is rigid with no joins

-          Because of the requirements are not cleared earlier that why design issue may come out at the end of project.

Spiral Model: In traditional model risk factor is not taken care of. In spiral model Risk factor is taken care of. Risk is probability of occurrence of error at any instance of time. The spiral model was introduced by Barry Boehm in 1986. In this model we can assume at max of 6 spirals or cycles. Cycles starts with Conception and end with the reviewed by consumer.

                 

Advantages of Spiral model:

-          It is the model in which Risk factor is involved and entertained.

-          We can implement this model for safety / Real time projects.

-          Documentation and frequent changes in requirements are easy to maintain and traceable

-          Testing activates is carried out at early stages of conception.

Disadvantages of Spiral model:

-          Implementing of this model is costly.

-          High Proficiency is required to analysis on risk factor. Project success and failure is dependent on analyzing the risk factor.

Models | Water Fall Model | VV Model | Iterative Incremental Model | Spiral Model