2 Yazılım Yaşam Döngüsü Tanımı Yazılım geliştirmek için modellerBir aktivite seti ve aralarındaki ilişkileri belirlerÖrnekler:Analiz, tasarım, uygulama, testTasarım analize dayanır, test uygulamadan önce başlayabilirDo I need analysis if I program bubblesort?
3 A Typical Example of Software Lifecycle Activities SystemDesignDetailedImplemen-tationTestingRequirementsElicitationAnalysis
4 Yazılım Yaşam Döngüsü Aktiviteleri ve Modeller SystemTasarımıDetaylıTasarımUygulamaTestGereksinimToplanmasıAnalizAltSystemlerStructured byclass...SourceCodeImplemented bySolution DomainObjectsRealized byApplicationDomainExpressed in terms ofTestCaseModel?VerifiedByclass....Use CaseModeli
5 Yazılım Yaşam Döngüsü Aktiviteleri RequirementsElicitationAnalysisSystemDesignDetailedDesignImplemen-tationTestingImplementedByExpressed in Terms OfStructured ByRealized ByVerifiedByclass...?class....?ApplicationDomainObjectsUse CaseModelSolution DomainObjectsSubsystemsSourceCodeTestCase Model
6 Gereksinimimleri Belirlemede İlk Adım: Sistemin Tanımlanması İki soruya cevap bulmamız lazım:Sistemin amaçını nasıl belirleyebiliriz?Gereksinimler ve kısıtlamalar neler?Neler sistemin içinde , neler sistemin dışında?Gereksinim toplama ve analiz aktiviteleri bu iki soruya cevap bulmaya çalışırGereksimim toplama:Müşeri veya kullanıcı gözüyle sistemin tanımlanması (“Requirements specification”)Analiz:Geliştirici gözüyle sistemin tanımlanması(Technical specification, “Analysis model”)Gereksinim Prosesi: Gereksinim toplama ve analiz aktivitelerinin toplamıRequirements identification consists of two activities:Requirements elicitation and AnalysisThe identification of objects and the definition of the system boundary are heavily intertwined with each other.
7 Gereksimin toplama teknıkleri Kullanıcı ve geliştirici arasında köprünün kurulması:Anketler (Questionnaires): Asking the end user a list of pre-selected questionsGörev analizleri (Task Analysis): Observing end users in their operational environmentSenaryolar (Scenarios): Describe the use of the system as a series of interactions between a specific end user and the systemUse case’ler: Abstractions that describe a class of scenarios.
8 SenaryolarSenaryoSistemin kullanımı ile ilgili text tabanli tarif. Tarif son kullanıcının bakış acısıyla yazılmışİş yeri, sosyal durumlar ve kaynaklar ile ilgili detaylar içerir. Text, video, resim içerebilir.Sistemin tek bir özelliğinin tek bir aktör tarafından kullanımının basit, odaklanmış, formal olmayan tarifiSenaryo yeni bir tasarımın daha iyi anlaşılması için temel bir iletişim şeklidir.Central to most scenario based design is a textual description or narrative of a use episode. This description is called a scenario.The scenario is described from the user point of view and may include social background, resource (e.g. disk space, time) constraints and background information.The scenario may describe a currently occurring use, or a potential use that is being designed and may include text, video, pictures, story boards, etc. By using a narrative it is possible to capture more information about the user's goals, and the context the user is operating in.The context might include details about the work place or social situation, and information about resource constraints. This provides some more help in understanding why users do what they do. In much current design work the users goals and context are often assumed implicitly, or may not be taken into account.
9 Senaryoya Dayalı Tasarım Yazılım yaşam döngüsü içinde senaryolar değişik aktivitelerde kullanılabilirGereksimin toplanmasında: Gerçek Senaryolar (As-is scenario), Geleceğe Dönük Senaryolar (visionary scenario)Müteri Kabul Testi (Client Acceptance Test): Evaluation scenarioSistemin Teslim edilmesi: Training scenarioSenaryoya Dayalı Tasarım :Scenario-based design is iterativeEach scenario should be consisered as a work document to be augmented and rearranged (“iterated upon”) when the requirements, the client acceptance criteria or the deployment situation changes.Scenarios are not really new. They have been commonly used to imagine "what if" situations and also in code walk-throughs.Here scenarios become design objects or artifacts and may be augmented and rearranged as the design evolves
10 Types of Scenarios Gerçek Senaryo (As-is scenario): Describes a current situation. Commonly used in re-engineering projects. The user describes the systemExample: Description of Letter-ChessGeleceğe Dönük Senaryolar (Visionary scenario):Describes a future systemExample: Home Computer of the FutureOften used in greenfield engineering and interface engineering projects.
11 Additional Types of Scenarios (2) Değerlendirme Senaryoları (Evaluation scenario):Description of a user task against which the system is to be evaluated.Example: Four users (two novice, two experts) play in a TicTac Toe tournament in ARENA.Eğitim Senaryoları (Training scenario):A description of the step by step instructions that guide a novice user through a systemExample: How to play Tic Tac Toe in the ARENA Game Framework.
12 Senaryoları Nasıl Buluruz? Don’t expect the client to be verbose if the system does not existClient understands the application domain (problem domain), not the solution domainDon’t wait for information even if the system exists“What is obvious does not need to be said”Engage in a dialectic approachYou help the client to formulate the requirementsThe client helps you to understand the requirementsThe requirements evolve while the scenarios are being developed.Don’t expect the client to be verbal if the system does not exist (greenfield engineering)Engage in a dialectic approach (evolutionary, incremental engineering)
13 Heuristics for finding scenarios Ask yourself or the client the following questions:What are the primary tasks that the system needs to perform?What data will the actor create, store, change, remove or add in the system?What external changes does the system need to know about?What changes or events will the actor of the system need to be informed about?However, don’t rely on questions and questionnaires aloneInsist on task observation if the system already exists (interface engineering or reengineering)Ask to speak to the end user, not just to the clientExpect resistance and try to overcome it.Imagine a GPS-based navigation system replacing a paper-based map.What are the primary tasks: Initialization, getting the current fix, finding north.What date will the actor create: On a map: Pencil the date when a summit was climbed, maybe on the edge of the map a little note , comparison of planned vs. actual route.GPS: Additional data Storage of traveled route, accumulation of total miles driven so far, miles climbed so far.What external changes does the system need to know about: Map: Nothing, paper cannot be notified, GPS: Change of locationWhat changes does the actor need to know: New map has been issued, road repair sites, congestions, hidden radars behind a curve.
14 Scenario örneği: İşyeri yangını Polis memuru olan İsmail arabası ile caddeden aşağıya giderken bir iş yerinden duman çıktığını görüyor. Arkadaşı Mustafa arabadan acil durumu rapor ediyor.Mustafa mobil bilgisayarına olay yerinin adresini ve acil durumun seviyesini veriyor.Yazdığı raporu oyaylıyor ve cevap gelmesini bekliyor;Merkezde görevli olan Emine Hanım bilgisayarından gelen sesli uyarı ile acil durumdan haberdar oluyor. Mustafa’nın gönderdiği bilgileri kontrol edip onaylıyor. Olay yerine gitmek üzere bir iftaye aracı, ambulans görevlendirip tahmini varış süresini Mustafa’ya yoılluyor.Mustafa raporun onaylandığını ve araçların olay yerine tahmini varış sürelerini görüyor ...
15 Observations about the Warehouse on Fire Scenario It is a concrete scenarioIt describes a single instance of reporting a fire incidentIt does not describe all possible situations in which a fire can be reportedParticipating actorsBob, Alice and John.What type?As-is, visionary, evaluation, training?
16 After the scenarios are formulated Find all the use cases in the scenario that specify all instances of how to report a fireExample from the Warehouse on Fire scenario:“Bob… notices smoke coming out of a warehouse. His partner, Alice, reports the emergency from her car”“Report Emergency“is a candidate for a use caseDescribe each of these use cases in more detailParticipating actorsDescribe the entry conditionDescribe the flow of eventsDescribe the exit conditionDescribe exceptionsDescribe nonfunctional requirementsThe set of all use cases is the basis for the Functional Model(see next lecture)Next goal after all the scenarios are formulated is to find all the uses cases in the scnario
17 Requirements Elicitation: Difficulties and Challenges Accurate communication about the domain and the systemPeople with different backgrounds must collaborate to bridge the gap between end users and developersClient and end users have application domain knowledgeDevelopers have solution domain knowledgeIdentification of an appropriate system (Definition of the system boundary)Provision of an unambiguous specificationLeaving out unintended features=> 3 Examples.Challenging activityEnd user with knowledge about the application domain, usually not very vocal, often unclear about IT requirements and even afraid, what the new system is going to do the dailyRoutine.Subject matter expert, knowledgeable about the subject, available for the creation of entity objects and for the provision of taxonomies or their formation.Developer with solution domain knowledge (design knowledge, implementation knowledge), often not very knowledgeable about the small and large problems of the application domain.
18 Example of an Ambiguous Specification During an experiment, a laser beam was directed from earth to a mirror on the Space Shuttle DiscoveryThe laser beam was supposed to be reflected back towards a mountain top 10,023 feet highThe laser beam was supposed to be reflected back towards a mountain top 10,023 feet highSo the laser beam was pointing to a mountain miles high.The operator entered the elevation as “10023”The light beam never hit the mountain topWhat was the problem?The computer interpreted the number in miles...
19 Example of an Unintended Feature From the News: London underground train leaves station without driver!What happened?A passenger door was stuck and did not closeThe driver left his train to close the passenger doorHe left the driver door openHe relied on the specification that said the train does not move if at least one door is openWhen he shut the passenger door, the train left the station without him. Why?The driver door was not treated as a door in the source code!
20 Requirements Process UML Activity Diagram Requirements elicitation :problemstatementRequirementselicitationRequirementsSpecification:functionalmodel:nonfunctionalrequirementsAnalysisThis is an Activity diagram showingh the activities and products of the requirements engineering process.Analysis Model:dynamic model:analysis objectmodelUML Activity Diagram
21 Requirements Specification vs Analysis Model Both are models focusing on the requirements from the user’s view of the systemThe requirements specification uses natural language (derived from the problem statement)The analysis model uses a formal or semi-formal notationRequirements Modeling LanguagesNatural LanguageGraphical Languages: UML, SysML, SA/SDMathematical Specification Languages: VDM (Vienna Definition Method), Z (based on Zermelo–Fraenkel set theory), Formal methods ….Formal methods:The Vienna Development Method (VDM) is one of the longest-established Formal Methods for the development of computer-based systems. Originating in work done at IBM's Vienna Laboratory in the 1970s, it has grown to include a group of techniques and tools based on a formal specification language - the VDM Specification Language (VDM-SL). It has an extended form, VDM++, which supports the modeling of object-oriented and concurrent systems. Support for VDM includes commercial and academic tools for analyzing models, including support for testing and proving properties of models and generating program code from validated VDM models. There is a history of industrial usage of VDM and its tools and a growing body of research in the formalism has led to notable contributions to the engineering of critical systems, compilers, concurrent systems and in logic for computer science.named after Zermelo–Fraenkel set theory, is a formal specification language used for describing and modelling computing systems.Abrial answers the question "Why Z?" with "Because it is the ultimate language!"Comparison: SA/SD vs OO:
22 Gereksinim Tipleri Fonksiyonel gereksinimler Sistemin çevresi ile olan aktivitelerini uygulamadan bağımsız olarak tarif ederFonnksiyonel olmayan gereksinimlerFonksiyonalite ile direkt bağlantılı olmayan aktiviteler“sistem bir saniyede cevap vermeli”KısıtlamalarMüşteri veya ortam tarafından oluşturulmuş kısıtlamalar“Uygulama Java’da yapılmalı “Also called “Pseudo requirements”.Constraints (“Pseudo requirements”):Imposed by the client or the environment in which the system operatesThe implementation language must be JavaARENA must be able to dynamically interface to existing games provided by other game developersFunctional requirements:Describe the interactions between the system and its environment independent from implementation“An operator should be able to define a new game. “Nonfunctional requirements:User visible aspects of the system not directly related to functional behavior.“The response time must be less than 1 second”“The server must be available 24 hours a day”“The implementation language must be Java “
23 Functional vs. Nonfunctional Requirements Describe user tasks which the system needs to supportPhrased as actions“Advertise a new league”“Schedule tournament”“Notify an interest group”Nonfunctional RequirementsDescribe properties of the system or the domainPhrased as constraints or negative assertions“All user inputs should be acknowledged within 1 second”“A system crash should not result in data loss”.Note: Many nonfunctional requirements can be rephrased as functional requirements.Example: “All actions are undoable” can be rephrased by adding a functional requirement for eachundoable action.For example, the use case “Advertise new league” yields a new use case “Cancel advertised league” toundo the effects of the first one.
24 Fonksiyonel olmayan gereksinim çeşitleri Kullanılabilirlik (Usability)Güvenilirlik (Reliability)Sağlamlık (Robustness)Güvenlilik (Safety)Performans (Performance)Geri dönme süresi (Response time)Büyümede esneklik (Scalability)Birim zamanda yapılan iş (Throughput)Erişilebilirlilik (Availability)Desteklenebilirlilik (Supportability)Adapte Edilebilirlilik (Adaptability)Devamlılık (Maintainability)Uygulama (Implementation)Arayüz (Interface)Operayon (Operation)Paketleme (Packaging)LegalLicensing (GPL, LGPL)CertificationRegulationConstraints or Pseudo requirementsQuality requirements
25 Some Quality Requirements Definitions UsabilityThe ease with which actors can perform a function in a systemUsability is one of the most frequently misused terms (“The system is easy to use”)Usability must be measurable, otherwise it is marketingExample: Specification of the number of steps – the measure! - to perform a internet-based purchase with a web browserRobustness: The ability of a system to maintain a functioneven if the user enters a wrong inputeven if there are changes in the environmentExample: The system can tolerate temperatures up to 90 CAvailability: The ratio of the expected uptime of a system to the aggregate of the expected up and down timeExample: The system is down not more than 5 minutes per week.
26 A Task for YouLook up the remaining definitions for the nonfunctional requirements and internalize themUnderstand their meaning and scope (their applicability).
27 Nonfunctional Requirements: Examples “Spectators must be able to watch a match without prior registration and without prior knowledge of the match.”Usability Requirement“The system must support 10 parallel tournaments”Performance Requirement“The operator must be able to add new games without modifications to the existing system.”Supportability Requirement
28 What should not be in the Requirements? System structure, implementation technologyDevelopment methodologyA rational design process: How and why to fake it (Parnas, 1986)Development environmentImplementation languageReusabilityIt is desirable that none of these above are constrained by the client.It is desirable that none of these above are constrained by the client. Fight for it!
29 Gereksinimlerin doğrulanması (Requirements Validation) Requirements validation is a quality assurance step, usually performed after requirements elicitation or after analysisDoğruluk (Correctness):The requirements represent the client’s viewBütünlük (Completeness):All possible scenarios, in which the system can be used, are describedTutarlılık (Consistency):There are no requirements that contradict each other.Requirements validation is a quality assurance step, usually after requirements elicitation or analysis.Completeness:All possible scenarios, in which the system can be used, are described, including exceptional behavior by the user or the systemProblem with requirements validation:Requirements change quickly during requirements elicitation.Inconsistencies are easily added with each changeTool support is needed!
30 Gereksinimlerin doğrulanması(2) Açıklık (Clarity):Requirements can only be interpreted in one wayGerçekçilik (Realism):Requirements can be implemented and deliveredTakip Edilebilirlilik (Traceability):Each system component and behavior can be traced to a set of functional requirementsProblems with requirements validation:Requirements change quickly during requirements elicitationInconsistencies are easily added with each changeTool support is needed!Requirements validation is a quality assurance step, usually after requirements elicitation or analysis.Completeness:All possible scenarios, in which the system can be used, are described, including exceptional behavior by the user or the systemProblem with requirements validation:Requirements change quickly during requirements elicitation.Inconsistencies are easily added with each changeTool support is needed!
31 Tools for Requirements Management (2) DOORS (Telelogic)Multi-platform requirements management tool, for teams working in the same geographical location. DOORS XT for distributed teamsRequisitePro (IBM/Rational)Integration with MS WordProject-to-project comparisons via XML baselinesRD-Link (http://www.ring-zero.com)Provides traceability between RequisitePro & Telelogic DOORSUnicase (http://unicase.org)Research tool for the collaborative development of system modelsParticipants can be geographically distributed.DOORS provides a proven, reliable foundation for a requirements-driven development processto achieve seamless communication, tight collaborationand efficient validation throughout the enterprise.DOORS provides:･Gap analysis of unaddressed requirements.･Graphical volatility displays that help users identify areas of greatest change.･Traceability analysis to help identify areas of risk.･Point-and-click views depicting relevant data for each type of user role.･Comprehensive, multi-level impact reports highlighting everything from the requirements to the tests that are likely to be affected by the next change.RequisitPro:Another Requirements and use case management toolThe IBM/Rational RequisitePro solution is a requirements and use case management tool for project teams who want to improve the communication of project goals, enhance collaborative development, reduce project risk and increase the quality of applications before deployment.Uses advanced integration with Microsoftｨ Word to provide a familiar environment for activities such as requirements definition and organizationIncorporates a powerful database infrastructure with real-time Word document synchronization to facilitate requirements organization, integration and analysisEnables detailed attribute customization and filtering to maximize informative value of each requirementﾊProvides detailed traceability views that display parent/child relationships and show requirements that may be affected by upstream or downstream change.Performs project-to-project comparisons using exportable XML-based project baselinesﾊIntegrates with multiple tools in the IBM Software Development Platform to improve accessibility and communication of requirementsRD-Linkis Ring-Zero technlogy that enables traceability between IBM/Rational RequisitePro and Telelogic DOORS. In the traceability matrix below, we can see DOORS requirements (the columns) being traced to RequisitePro requirements (rows). The software requirements (SR's) in Requisite Pro are being driven by the system requirements in DOORS (SAMPLE's).It is possible to use RD-Link for many different usage scenarios. DOORS could contain "master requirements", "tests", "implementation requirements", anything that is important for traceability. And RequisitePro could hold either dependent requirements or master requirements that DOORS will then depend on.And traceability can be established either direction, either "trace to" DOORS or "trace from" DOORS depending on what problem is being solved. When the requirements in DOORS change, RequisitePro is updated and traceability/suspect flags set appropriately. Thus, RequisitePro and DOORS can be used in a cooperative fashion.
32 We can specify the Requirements for a “Requirements Management” System Functional requirements:Store the requirements in a shared repositoryProvide multi-user access to the requirementsAutomatically create a specification document from the requirementsAllow change management of the requirementsProvide traceability of the requirements throughout the artifacts of the system.DOORS provides a proven, reliable foundation for a requirements-driven development processto achieve seamless communication, tight collaborationand efficient validation throughout the enterprise.DOORS provides:･Gap analysis of unaddressed requirements.･Graphical volatility displays that help users identify areas of greatest change.･Traceability analysis to help identify areas of risk.･Point-and-click views depicting relevant data for each type of user role.･Comprehensive, multi-level impact reports highlighting everything from the requirements to the tests that are likely to be affected by the next change.RequisitPro:RD-Linkis Ring-Zero technlogy that enables traceability between IBM/Rational RequisitePro and Telelogic DOORS. In the traceability matrix below, we can see DOORS requirements (the columns) being traced to RequisitePro requirements (rows). The software requirements (SR's) in Requisite Pro are being driven by the system requirements in DOORS (SAMPLE's).It is possible to use RD-Link for many different usage scenarios. DOORS could contain "master requirements", "tests", "implementation requirements", anything that is important for traceability. And RequisitePro could hold either dependent requirements or master requirements that DOORS will then depend on.And traceability can be established either direction, either "trace to" DOORS or "trace from" DOORS depending on what problem is being solved. When the requirements in DOORS change, RequisitePro is updated and traceability/suspect flags set appropriately. Thus, RequisitePro and DOORS can be used in a cooperative fashion.
33 Different Types of Requirements Elicitation Greenfield EngineeringDevelopment starts from scratch, no prior system exists, requirements come from end users and clientsTriggered by user needsRe-engineeringRe-design and/or re-implementation of an existing system using newer technologyTriggered by technology enablerInterface EngineeringProvision of existing services in a new environmentTriggered by technology enabler or new market needsGreenfield EngineeringDevelopment starts from scratch, no prior system exists, requirements are extracted from end users and clientTriggered by user needs>>>>> Example: Develop a game from scratch.Re-engineeringRe-design and/or re-implementation of an existing system using newer technologyTriggered by technology enabler>>>>>Example: Reengineer an existing gameInterface EngineeringProvide services of existing system in new environmentTriggered by technology enabler or new market needsExample: Interface to an existing game, the game was developed for a local computer, now we want to offer a multiplayer-version, that can be played in a LAN-party.
34 Prioritizing Requirements High priorityAddressed during analysis, design, and implementationA high-priority feature must be demonstratedMedium priorityAddressed during analysis and designUsually demonstrated in the second iterationLow priorityAddressed only during analysisIllustrates how the system is going to be used in the future with not yet available technology.High priority (“Core requirements”)Must be addressed during analysis, design, and implementation.A high-priority feature must be demonstrated successfully during client acceptance.Medium priority (“Optional requirements”)Must be addressed during analysis and design.Usually implemented and demonstrated in the second iteration of the system development.Low priority (“Fancy requirements”)Must be addressed during analysis (“very visionary scenarios”).Illustrates how the system is going to be used in the future if not yet available technology enablers are available
35 Requirements Analysis Document Template 1. Introduction2. Current system3. Proposed system3.1 Overview3.2 Functional requirements3.3 Nonfunctional requirements3.4 Constraints (“Pseudo requirements”)3.5 System models3.5.1 Scenarios3.5.2 Use case model3.5.3 Object modelData dictionaryClass diagrams3.5.4 Dynamic models3.5.5 User interface4. GlossaryBruegge & Dutoit, 3rd edition, pp. 152
36 Section 3.3 Nonfunctional Requirements 3.3.1 User interface and human factors3.3.2 Documentation3.3.3 Hardware considerations3.3.4 Performance characteristics3.3.5 Error handling and extreme conditions3.3.6 System interfacing3.3.7 Quality issues3.3.8 System modifications3.3.9 Physical environmentSecurity issuesResources and management issues
37 Nonfunctional Requirements (Questions to overcome “Writers block”) User interface and human factorsWhat type of user will be using the system?Will more than one type of user be using the system?What training will be required for each type of user?Is it important that the system is easy to learn?Should users be protected from making errors?What input/output devices are availableDocumentationWhat kind of documentation is required?What audience is to be addressed by each document?
38 Nonfunctional Requirements (2) Hardware considerationsWhat hardware is the proposed system to be used on?What are the characteristics of the target hardware, including memory size and auxiliary storage space?Performance characteristicsAre there speed, throughput, response time constraints on the system?Are there size or capacity constraints on the data to be processed by the system?Error handling and extreme conditionsHow should the system respond to input errors?How should the system respond to extreme conditions?
39 Nonfunctional Requirements (3) System interfacingIs input coming from systems outside the proposed system?Is output going to systems outside the proposed system?Are there restrictions on the format or medium that must be used for input or output?Quality issuesWhat are the requirements for reliability?Must the system trap faults?What is the time for restarting the system after a failure?Is there an acceptable downtime per 24-hour period?Is it important that the system be portable?Is it important that the system be portable(able to move to different hardware or operating system environments)?
40 Nonfunctional Requirements (4) System ModificationsWhat parts of the system are likely to be modified?What sorts of modifications are expected?Physical EnvironmentWhere will the target equipment operate?Is the target equipment in one or several locations?Will the environmental conditions be ordinary?Security IssuesMust access to data or the system be controlled?Is physical security an issue?Will the environmental conditions in any way be out of the ordinary (for example, unusual temperatures, vibrations, magnetic fields, ...)?
41 Nonfunctional Requirements (5) Resources and Management IssuesHow often will the system be backed up?Who will be responsible for the back up?Who is responsible for system installation?Who will be responsible for system maintenance?
42 Heathrow Luggage System On April 5, 2008 a system update was performed to upgrade the baggage handling:50 flights were canceled on the day of the updateA “Bag Backlog” of 20,000 bags was produced (Naomi Campbell had a fit and was arrested)The bags were resorted in Italy and eventually sent to the passengers via Federal ExpressWhat happened? Explanation:Computer failure in the high storage bay area in combination with shortage of personal
43 Heathrow Luggage System Requirements Automate the processing of No-Show passengersUse a high bay storage area (“high rack warehouse”)Provide a chaotic storage capabilityCombine two existing luggage systems (“legacy systems”): Early (hours before) and last minute checkinsThe system must be tested with 2500 volunteersThe throughput must be at least suitcases/hourUse available information on the internet:
44 Additional Readings Scenario-Based Design David Parnas John M. Carrol, Scenario-Based Design: Envisioning Work and Technology in System Development, John Wiley, 1995Usability Engineering: Scenario-Based Development of Human Computer Interaction, Morgan Kaufman, 2001David ParnasA rational design process: How and why to fake it, IEEE Transactions on Software Engineering, Volume 12 , Issue 2 (February 1986)Heathrow Luggage System:Additional Information about Heathrow (In German)Panne auf Flughöhe Null (Spiegel):Zurück in das rotierende Chaos (FAZ):OMG Systems Modeling Language (SysML 1.1):November 2008
46 A Visionary Scenario from 1954: The Home Computer in 2004 Is this a fake picture? Some people claim that it is.Everybody scratches their head for a minute after first seeing the graphic.Popular Mechanics actually published an article in 2004 about this: ” But after a closer look, everyone agrees that something wasn't quite rightMore research revealed, much to our relief, that this was one prediction we did not make”
47 It is amanipulated photo of a mock submarine console passed off as a 1950s projection of the 2004 home computer,The picture was actually used by Sun Microsystems Chief Executive Scott McNealy in his Oracle OpenWorld keynote speech yesterday in San Francisco in 2002 to illustrate how rapidly technology improves.And Lotus founder Mitch Kapor actually posted the image on his blog before later posting a correction.Note, even if it is a fake, if we would have published it in 1954, it would have been a visionary scenario for 2004, that proved wrong:-)
48 Maneuvering room of a U.S. nuclear submarine (Smithsonian Museum) Albeit significantly doctored, what you are actually looking at in the image above is a full-scale mock-up of the maneuvering room of a U.S. nuclear submarine, not a "home computer" as envisioned in 1954The original picture, snapped by an unknown photographer at a Smithsonian Institution exhibit called "Fast Attacks and Boomers: Submarines of the Cold War,” was chosen to be the fodder for a Fark.com Photoshop contest in September This altered image, including a new caption invented for the occasion, was one entry in that contest
50 Heathrow Luggage as an Exercise: Trigger Questions Your task: Reverse engineer the requirements for the Heathrow luggage systemUse the requirements analysis document templateUse available information on the internet.Questions to ask:How are the bags stored after passengers have checked, but before they enter the plane?How are the bags retrieved from the storage area?What about existing luggage systems (“legacy systems”)?Scalability: How many users should the new luggage system support? How can this be tested before deployment?Throughput: How many suit cases/hour need to be supported?Bonus Task:What changes to the requirements should have been done to avoid the Heathrow desaster?