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Soft lifecycle

  2. 2. Life cycle model To Describes the steps followed by the project team to produce a tangible software product that fully meets the requirements of the component or the part that the project set forth to build.
  3. 3. Software Process A set of activities, together with ordering constraints among them, such that if the activities are performed properly and in accordance with the ordering constraints. The process that deals with the technical and management issues of software development is called SWP. Successful project talks about Cost, schedule and quality.
  4. 4. Contd.. A set of activities that leads to the production of a software product. There are many software processes, some fundamental activities are common to all software processes: Software Specification Software design and Implementation Software Validation Software evolution.
  5. 5. Software process Product Engineering process(produce desired product) Development process Project Management process Software Configuration Management Process Management process
  6. 6. ETVX Approach for process specification Entry Criteria Task Verification Exit Criteria
  7. 7. A step in Development process Predictability. Input Output Process V&V
  8. 8. SDLC A software development process, also known as a software development life cycle (SDLC), is a structure imposed on the development of a software product.
  9. 9. Waterfall Model Linear Sequential Model Water – tight phases One phase is Completed before the next phase starts
  10. 10. Life cycle model
  11. 11. Waterfall model problems  Inflexible partitioning of the project into distinct stages makes it difficult to respond to changing customer requirements.  Therefore, this model is only appropriate when the requirements are well-understood and changes will be fairly limited during the design process.  Few business systems have stable requirements.  The waterfall model is mostly used for large systems engineering projects where a system is developed at several sites.
  12. 12. Limitations of Waterfall model It assumes that the requirements of a system can be frozen before the design begins. Freezing the requirements usually requires choosing the hardware(because it forms a part of the requirements specification). A large project might take a few years to complete. “Big bang approach” – an entire software is delivered in one shot at the end. It encourages “requirements bloating”. It is a document-driven process that requires formal documents at each phase.
  13. 13. Prototyping Model • Attractive idea for complicated and large systems for which there is no manual process or existing system to help determine the requirements.. • Based on Currently known requirements. • Customer can get actual feel of the system. Types: 1. Throwaway Prototype 2. Evolutionary Prototype
  14. 14. Contd.. Horizontal Prototype A common term for a user interface prototype is the horizontal prototype It provides a broad view of an entire system or subsystem, focusing on user interaction more than low-level system functionality, such as database access Vertical Prototype A vertical prototype is a more complete elaboration of a single subsystem or function.
  15. 15. Contd.. Types of prototyping Major types: first two.. Throwaway prototyping Evolutionary prototyping Incremental prototyping Extreme prototyping
  16. 16. Adv and Dis-Adv Advantages Reduced time and costs: Improved and increased user involvement Disadvantages of prototyping Insufficient analysis User confusion of prototype and finished system Developer misunderstanding of user objectives Expense of implementing prototyping: Excessive development time of the prototype
  17. 17. RAD Model Combines the features of waterfall model and prototyping model. Rapid application development (RAD) is a software dev.methodology that uses minimal planning in favor of rapid prototyping. WYSIWYG manner The "planning" of software developed using RAD is interleaved with writing the software itself. Each units Developed in a short time. Developments, using modelling tools and CASE, translates to product.
  18. 18. Contd.. Speed and Responsiveness. Loop continually, Changes and feedback reflected. Key to the success of RAD lies in application decomposition, automatic generation and effective re-use. DisAdv: Modelling tools add expenses and Place restrictions(decompose, re-use..) Not applicable in little or no customer involvement, Co- existence of new application in legacy system.
  19. 19. Iterative Development
  20. 20. Iterative Development Counters the Third and fourth limitation of waterfall model, tries to combine the benefits of prototyping and Waterfall. Based on incrementing and add some functional capability to system until it satisfies. Project control list, gives an idea of how far the projects moves.
  21. 21. Spiral Model Each cycle in the spiral begins with the identification of objectives for that cycle. Next step is to evaluate the different alternatives based on objectives and constraints. Resolve uncertainties and risks Software developed Final stage Planned.
  22. 22. Time Boxing Model The Timeboxing model for iterative software development in which each iteration is done in a time box of fixed duration, and the functionality to be built is adjusted to fit the time box.
  23. 23. RUP Rational Unified Process Designed for Object Oriented Development using UML. Divided into Cycles, each cycle delivering a fully working system. Each cycle have four phases:  Inception  Elaboration  Construction  Transition
  24. 24. RUP Phases  Inception: Goals and scope of project(life cycle objectives milestone)  Elaboration: Architecture of the system is designed, based on the detailed requirement analysis (lifecycle Architecture milestone).  Construction: software is built and tested(Initial operational capability milestone)  Transition: To move the software from development environment to client’s environment(product release milestone).
  25. 25. Agile processes  Extreme Programming  Extreme Programming is successful because it stresses customer satisfaction.  Extreme Programming emphasizes teamwork.  Extreme Programming improves a software project in five essential ways; 1. Communication 2. Simplicity 3. Feedback 4. Respect 5. Courage.
  26. 26. Principles of agile processes Working software is the key measure of progress Software should be developed and delivered in small increments. Late changes in requirements should be entertained. Face to face communication over documentation. Continuous feedback and involvement of customer. Simple design is better than elaborate design upfront. Delivery dates are decided by the empowered teams.
  27. 27. THANK YOU