Prototyping: alternative systems development methodology by J M CareyWhat is Prototyping?What is prototyping?Why use prototyping?Why prototype?Prototyping EnvironmentsFourth and Fifth Generation Software LanguagesThe generations of computer languagesSuccessful 4GL LanguagesTypes of PrototypingType I - IterativeType II - ThrowawayAdvantages of prototypingDisadvantages of prototypingWhen to prototypeWhen not to prototypeMethodologyIncorporating Human FactorsSome good guidelinesCase Study- NJ DMVWhat went wrong?How did they fix it?Case Study: Town and Country Credit LineWhat went right?SummaryMy opinionAdditional References1Prototyping: alternative systems development methodology by J M Carey Presented by Cynthia JohnsonFebruary 7, 2007 EEL 68832What is Prototyping?“’Prototyping’ is the process of quickly building a model of the final software system, which is used primarily as a communication tool to assess and meet the information needs of the user?” – J M Carey3What is prototyping?“Prototyping is the use of approximately 30% of the ultimate staff to build one or two working versions of various aspects of a system. It is not production code but it may eventually become pre-production code or it may be completely discarded. In the prototyping effort, we are not concerned with the maintainability of the code nor are we concerned with formally documenting it.” – Larry Bernstein4Why use prototyping?Helps user clarify their needsLess ambiguous than traditional narrative function specificationImproves team communication. “A picture is worth a 1000 words”Less emphasis on time consuming documentationGenerally faster than traditional development5Why prototype?The prototype provides a vehicle for systems engineers to better understand the environment and the requirements problem being addressed. A prototype is a demonstration of what's actually feasible with existing technology, and where the technical weak spots still exist. A prototype lets the developer meet earlier schedules for the production version. A prototype allows for early customer interaction.6Prototyping EnvironmentsTwo major types of prototyping environments mentioned.Automated development environmentsPrototyping toolkits – a collection of unintegrated tools.7Fourth and Fifth Generation Software LanguagesOften abbreviated 4GL, fourth-generation languages are programming languages which are closer to human language than previous languages. Most of today’s 4GLs are database languages. One example is FIND ALL RECORDS WHERE NAME IS "SMITH"8The generations of computer languages1st GenerationMachine Language2nd GenerationAssembly Language3rd GenerationC, C++, FORTRAN, Java, Pascal, Ada4th GenerationSQL, RPG-II5th GenerationUsed for artificial intelligence and neural networks – primarily researchers9Successful 4GL LanguagesDatabase QuerySQL, Progress 4GL, InformixReport GeneratorsBuildProfessional, PostScriptData Manipulation and ReportingClarion, GraphTalkScreen Painters, GUI DevelopersFourGen, Visual Basic10Types of PrototypingType I – IterativeType II - Throwaway11Type I - IterativeUses the Prototype as the final system after a series of iterative upgradesGenerally uses a 4GL tool for development12Type II - ThrowawayPrototype is developed in 4GL or toolkit Final product based on prototype built in 3GL language.13Advantages of prototypingFaster development timeEasier for end-users to learn to useMore end-user involvementEnhances user/analysts communicationRequirements are easier to determine.14Disadvantages of prototypingUndue user expectationsInconsistencies between prototype and final productFinal system inefficienciesLack of attention to good human factors practice.Inattention to proper design and analysis.15When to prototypeA good prototyping candidate isDynamicTransaction processing basedContains extensive user dialogsIs smallIs well definedIs online‘is’ the business16When not to prototypeA system with the following attributes is not a good candidateIs stableIs decision-support basedIs ill-definedMakes little use of user dialogsIs real-timeHas lots of number crunching17MethodologyFollowing good methodology is key to successful prototypingFour phases of prototype developmentDetermine what to prototypeBuild the prototypeTest the prototypeUse the prototype as a model18Incorporating Human FactorsPrototyping does nothing to ensure use of good human factors practices.The issue of “user friendly” or usability has become a huge determinant of system success.A system that works perfectly may be rejected if difficult to useNote that this is not an issue that applies just to prototypes.19Some good guidelinesKnow your userUse selection not entryMake the system behave predictablyMake the system unobtrusiveChange displays as little as possibleMinimize keystrokes and mouse useUse meaningful error messagesAllow for “undo”20Case Study- NJ DMVPrice Waterhouse contracted to build New Jersey’s DMV primary information system.They chose a new (at the time)4GL called Ideal from Applied Data Research to develop the systemWhen delivered, the response time was so slow that the backlog required thousands of hours of overtime21What went wrong?Ideal was new and untested. Little time was spent training staff in its useThe contract imposed bigger penalties for late system than a non performing oneThey ignored consultants warnings that Ideal was not the right tool.22How did they fix it?By converting 58 of 800 modules to COBOL, system performance was made acceptable.Those 58 modules performed 85% of the systems work.23Case Study: Town and Country Credit LineBanking card system improvementHired consultants to help them choose IEF (Information Engineering Facility) from Texas InstrumentsUsed Iterative prototyping and delivered a successful system24What went right?Tool was 5 years more advanced than IdealThey did a more extensive study of available tools before choosingLearned from others’ mistakes25SummaryPrototyping is made possible by the availability of 4GLs and soon 5GLNot all systems are good candidates for prototypingFor those that are, prototyping can reduce development time and costPrototyping does not ensure good human factors26My opinionI’m not a big fan of type II prototyping. Anything that gets thrown away seems wasteful and end product may not match prototype.Iterative prototyping is good for working out incompletely defined user interfacesCustomer is usually happier when they have up front