Software Engineering Process Models important
- 2. What is software process? ▪ A software process (also knows as software methodology) is a set of related activities that leads to the production of the software. ▪ These activities may involve the development of the software from the scratch, or, modifying an existing system. ▪ Any software process must include the following four activities:
- 3. 1. Software specification (or requirements engineering): Define the main functionalities of the software and the constrains around them. Software design and implementation: The software is to be designed and programmed. Software verification and validation: The software must conforms to it’s specification and meets the customer needs. Software evolution (software maintenance): The software is being modified to meet customer and market requirements changes.
- 4. Software Process Paradigms ▪ A software process model is a simplified representation of a software process. Each model represents a process from a specific perspective. ▪ The following are the most used Software Process models, they are 1. Waterfall model 2. Prototyping Model 3. Incremental Model 4. spiral Model 5. RAD Model
- 5. Waterfall model ▪ The waterfall model is a sequential approach, where each fundamental activity of a process represented as a separate phase, arranged in linear order. ▪ In the waterfall model, you must plan and schedule all of the activities before starting working on them (plan-driven process). ▪ The phases of the waterfall model are: Requirements, Design, Implementation, Testing, and Maintenance.
- 7. ▪ the result of each phase is one or more documents that should be approved and the next phase shouldn’t be started until the previous phase has completely been finished. ▪ The waterfall model should only be applied when requirements are well understood and unlikely to change radically during development as this model has a relatively rigid structure which makes it relatively hard to accommodate change when the process in underway.
- 8. Prototyping Model: In the prototyping paradigm In the prototyping paradigm 1. 1.The user specifies the basic requirements of the system. The user specifies the basic requirements of the system. 2. 2.The engineer(s) develop a working model (prototype) of the The engineer(s) develop a working model (prototype) of the specified system which focuses on the major functionalities of specified system which focuses on the major functionalities of the system. the system. 3. 3.The prototype is then given to the customer for trial. The prototype is then given to the customer for trial. 4. 4.The customer provides the feedback after evaluating the The customer provides the feedback after evaluating the prototype which helps in refining the requirements for the prototype which helps in refining the requirements for the final product. final product. 5. 5.Improving the prototype & testing it continues till the final Improving the prototype & testing it continues till the final
- 10. Advantages and Disadvantages Advantages: The customer gets the feel of the system with the working version The engineer gets much clearer picture of what is needed with each feedback provided by the customer Disadvantages: The customer can’t wait till the prototyping process leads to the end product & is willing to get the prototype “fixed” to get the final product The engineers might make implementation compromises while designing the prototype, which can thereafter be ignored at the time of final product development
- 11. Incremental Model: In this paradigm In this paradigm 1.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. 2. It involves both development and maintenance 3.The product is defined as finished when it satisfies all of its requirements. 4.This model combines the elements of the waterfall model with the iterative philosophy of prototyping.
- 12. 4. This model combines the elements of the waterfall model with the iterative philosophy of prototyping.
- 13. Advantages of Incremental Model •Generates working software quickly and early during the software life cycle. •More flexible – less costly to change scope and requirements. •Easier to test and debug during a smaller iteration. •Easier to manage risk because risky pieces are identified and handled during its iteration. •Each iteration is an easily managed milestone.
- 14. Disadvantages of Incremental Model •Each phase of an iteration is rigid and do not overlap each other. •Problems may arise pertaining to system architecture because not all requirements are gathered up front for the entire software life cycle. When to use Incremental Model •Such models are used where requirements are clear and can implement by phase wise. From the figure it’s clear that the requirements ® is divided into R1, R2……….Rn and delivered accordingly. •Mostly such model is used in web applications and product
- 15. Spiral Model: 1. The spiral model starts with an initial pass through a standard waterfall life cycle, using a subset of the total requirements to develop a robust prototype. 2. After an evaluation period, the cycle is initiated again, adding new functionality and releasing the next prototype. 3. This process continues, with the prototype becoming larger and larger with each iteration. 4. Spiral model is divided into set of framework activities defined by the software engineering team. 5. Each of the framework activities represent one segment of the
- 17. Advantages of Spiral Model •High amount of risk analysis •Good for large and mission-critical projects. •Software is produced early in the software life cycle. Disadvantages of Spiral Model •Can be a costly model to use. •Risk analysis requires highly specific expertise. •Project’s success is highly dependent on the risk analysis phase. •Doesn’t work well for smaller projects.
- 18. When to use Spiral Model •For a typical shrink-wrap application. •The spiral model is used most often in large projects. •The US military has adopted the spiral model for its Future Combat Systems program.
- 19. RAD Model: 1. Rapid Application Development or RAD is an incremental software process model that emphasizes a short development cycle. 2. The RAD model is a high speed adaption of the waterfall model, in which rapid development is achieved by using a component based construction approach. 3. The RAD process enables a development team to create a fully functional system with in very short
- 21. ▪ Communication works to understand the business problem and the information characteristics. ▪ Planning is essential because multiple software teams works in parallel on different systems. ▪ Modeling encompasses three major phases- business modeling, data modeling, and process modeling. ▪ Construction emphasizes the use of pre-existing software components and the application automatic code generation. ▪ Deployment establishes a basis for subsequent iterations.
- 22. Advantages of RAD •RAD reduces the development time and reusability of components help to speed up development. •All functions are modularized so it is easy to work with. •For large projects RAD require highly skilled engineers in the team. Disadvantages of RAD •Both end customer and developer should be committed to complete the system in a much abbreviated time frame. •If commitment is lacking RAD will fail. •RAD is based on Object Oriented approach and if it is difficult to modularize the project the RAD may not work