Question

• Describe the characteristics of each software development model: V-model, waterfall and iterative models/frameworks and the key development stages or phases of each.
• Identify the key test levels with each model and the main goal(s) of each level. Incorporate details from section 2.2 into your analysis.
• Identify the pros and cons of each model.
• Identify how testing responsibilities and the role of the tester changes across the various development stages or phases.
• Provide an overview of how each model compares and contrasts to the other software development models.
• Make an overall recommendation of which model you believe would be more effective in a typical software development project. Provide justification for your recommendation.
• Essay should be at least 450, but not more than 600 words with a list 2 Refrences

Answer 1

Waterfall Model :Waterfall model is the most ideal and simple way to develop software.
The classical waterfall model divides the life cycle of a software into 6 phases:
1) Feasibility study : The main focus of feasibility study is to determine whether it would be financially and technically feasible to develop the software. This phase consists of :
     i) Development of an overall understanding of the problem
     ii) Formulation of various possible strategies for solving the problem
     iii) Evaluation of the different solution strategies
2) Requirement Analysis and Specification: This phase consists of two distinct activities:
    i) Requirement gathering and analysis: Requirements are gathered from the customers and then the                                                                     gathered requirements are analysed.
   ii) Requirement specification: After the requirement gathering and analysis activities are complete, the                                                   identified requirements are documented.
3) Design: The goal of the design phase is to transform the requirements specified in the SRS document into a structure that is suitable for implementation in some programming language. Design can be procedural or object oriented.     
4) Coding and unit testing: This phase is used to translate a software design into source code and to ensure that individually each function is working correctly. Coding phase is also called Implementation phase. The modules coded are then tested under unit testing.
5) Integration and system testing : Integration of individual modules are done in a planned manner and the whole software undergoes system testing.
6) Maintenance: Corrective, perfective and adaptive maintenance is carried out in this phase to ensure the correct working and repair of any module if needed.

Development phase: The phases starting from feasibility study to integration and system testing.
Maintenance phase: It is the last phase of the life cycle.
Cons :
1) No feedback policy
2) Difficult to accommodate change requests
3) Inefficient error corrections
4) No overlapping of phases.

Pros:
The waterfall model is ideal but hard to use for real projects.

Iterative Waterfall Model: The main change brought about by the iterative waterfall model to the classical waterfall model is in the form of providing feedback paths from every phase to its preceding phases.
Special features and pros include:
1) Phase containment of errors: It is advantageous to detect the errors in the same phase in which they take place, since early detection of bugs reduces the effort and time required for correction.
2) Phase overlap: Overlapping phases help in detection of errors in the same phase where committed and helps in work division amongst programmers in a smooth and pipelined way.

Cons:
1) Difficult to accommodate change requests
2) Incremental delivery not supported.
3) Error correction is expensive
4) Limited Customer interactions
5) No support for risk handling and code reuse.

V- model : A variation of the waterfall model. Verification and validation carried out throughout the development life cycle.

Pros:
1) Much of the testing is carried out in parallel with the development.
2) Quality of test cases is usually better
3) More man power utilization as test team involved from the beginning itself.

Cons:
1) Feedback from customers yet not solved.
2) Being derived from waterfall model, it derives its weaknesses too.

Difference between V-model and waterfall model:
The main difference between waterfall model and V-model is that in waterfall model, the testing activities are carried out after the development activities are over. On the other hand in V-model, testing activities start with the first stage itself and carried out till the end. Waterfall model is a continuous process, while the V-model is a simultaneous process. Also making changes in the software in waterfall model is a difficult task, and also proves to be a costly affair than in V-model.


Please find the attachment of the images of the 3 different types of testing: The first one on the left top is classical water model.





According to me, V-model will prove to be a better choice in software development as the testing and validation methods are incorporated from the starting phases of the life cycle, which ensures the end product to be less erroneous. More so, nipping a bug in the code in its bud is easier than detecting and finding the errors and correcting them at the end phases.

Feasibility Study lel V-Model Requirment Analysis and Specification System Testing Requirement Analysis and Specification System test design Design Coding and Unit Testing High Level Design Integration Test design Integration testing Integration and System Testing Maintenance Coding Unit test design Unit Testing Iterative Model Feasibility Study Requirment Analysis and Specification Design Coding and Unit Testing Integration and System Testing Maintenance