Prototyping life cycle Important steps 1. Does prototyping suit the system 2. Abbreviated representation of requirements 3. Abbreviated design specification for the prototype. 4. Prototype created, tested and refined 5. Customer’s feedback after use of prototype accomodated 6. Repeat 4 and 5 until all requirements are formalized or until the prototype has evolved into a production system

Prototyping Prototype is the first model or it is a test or pilot project. We developed an idea to give the user an idea about the proposed system Prototyping can help the user to visualize how the proposed system will work. Prototyping can help the user to visualize how the proposed system will work. Is actual working model of the system Is actual working model of the system Prototyping provide refinement Prototyping provide refinement The objective of prototyping is to enhance the quality of the requirement specification The objective of prototyping is to enhance the quality of the requirement specification

Types of prototyping tools 1. Pencil and paper 2. Drawing software 3. Animation and slide show software 4. Visual tools 5. 4GLs

Advantages of prtotyping 1. Prototyping may be easily changed or even discarded 2. May improve communication between user and developer 3. User may be more satisfied with system developing prototype 4. A prototype may serve as a marketing tool 5. Early visibility of the prototype may help management assess progress 6. It may demonstrate progress at early stage of development

Advantages of prototype 8. It may prevent unpleasant surprises by calling attention to incomplete or inconsistent requirements, or to missing functionality 9. Prototyping may produce some useful deliverables even if the project runs out of time or money 10. It reduce misunderstanding b/w user and developer 11. It may reduce redesign costs if problems are detected early 12. It may reduce the time required for testing if problems are detected early

Advantages of prototype 13. It may require less effort (43% according Boehm,Gray & Seewaldt 1984) than conventional development 14. Prototyping may result in partnership b/w user and developer 15. Prototyping may result in a product that is a better fit for the customer’s requirements 16. Prototyping may save on initial costs, because customers are doing “acceptance testing “ all along the way 17. System produced through prototype may be judged easier to learn and easier to use 18. Using prototyping during development may reduce the amount of code that is finally written

Pitfalls (Risk) 1. Prototyping may encourage an excess of change requests 2. Working prototype may lead management and customers to believe that the final product is almost ready for delivery 3. Customer may not be prepared to provide the leval of frequency of feedback required for iterative prototyping 4. Customer may not be willing to participate in the iteration cycle over the long haul 5. Developer may have difficulty writing the back-end code needed to support the front end interface designed with the prototyping tool.

pitfalls 6. Due to time and market constraints, system specification may be frozen before the prototyping process has reached a definitive stage 7. Early prototypes may be of low quality, dismissed as toys 8. Hi-quality prototypes may be mistaken for a real product 9. Important system characteristics (performance,security,reliability) may have been ignored during prototype development 10. Prototype is an adaptive process that may not exhibit well defined phases

Pitfalls 11. Prototyping may continue too long because there may be no well defined completion criterion. 12. Prototyping may be useless if member of the team do not have enough decision making authority 13. Specification that emerge during later prototyping may reduce the structural integrity of the partially designed system 14. The context (environment) of use for the prototype may be very different from the context of use for the final system

Prototype is more likely to succeed when… 1. Used as a means to achieve early usability testing 2. Used to compare alternative designs 3. Used to evaluate a proposed interface 4. Used to explore the affect of change requests 5. Used to expose new or unexpected requirements 6. Used to involve the user in the design process 7. Used to model a system that has a significant user interface component 8. Used to a model that is relatively large and complex 9. Used to Provide a common basis for good communication b/w user and developer

Prototyping is more likely to fail when….. 1. No clear terminating criterion has been established to end the iterative development cycle 2. The expectations of customers are allowed go grow beyond reasonable bounds 3. The functionality of an operational prototype does not scale up to the functionality required of the final system 4. The opinions of the developers and customers diverge during the iterative phase 5. The project is too small to justify prototyping 6. Used to model system that present no external interface 7. Used to measure the future performance of the planned system 8. Used to market software that does not exist

Advantages of prototype User orientation User orientation Objective of prototyping is to develop a system that meet user needs Objective of prototyping is to develop a system that meet user needs Fast development time Fast development time At takes less time than a traditional approach At takes less time than a traditional approach Fewer errors Fewer errors It allows errors to be detected earlier It allows errors to be detected earlier More opportunity to changes More opportunity to changes

Disadvantages of prototypes Demand high cooperation b/w user and the developer Demand high cooperation b/w user and the developer Active users’ participation requires time that users may not be able to spend, particularly the managers Active users’ participation requires time that users may not be able to spend, particularly the managers Total development cost can be higher Total development cost can be higher If user is constantly making changes to the system, it may take high cost If user is constantly making changes to the system, it may take high cost Poor documentation or no documentation Poor documentation or no documentation Prototyping is an iterative process, as such constant updates of documentation is laborious and difficult Prototyping is an iterative process, as such constant updates of documentation is laborious and difficult