Chapter2 bag1

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Chapter2 bag1

  1. 1. Faculty of Engineering - Universitas Indonesia Requirement Engineering (part 1) Prof. Dr.-Ing. Kalamullah Ramli Electrical Engineering Department
  2. 2. Requirement Study o Requirement are ubiquitous part of our lives o Understand the requirement through communication o Communication Problem? • People are hard to understand! Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 2
  3. 3. Human Nature Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 3
  4. 4. Change is Constant o What makes the change? • Human nature • Society • Organization • Competitors o DESIGN: shooting at moving target! Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 4
  5. 5. Why Requirement Study? o Limitation of the designers o Motivation o Reduce the total cost o How far shall we make the requirement analysis? Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 5
  6. 6. Failure of Requirement Analysis o The penalty of getting Requirement Engineering (RE) wrong is high o Even the system did not fall, user is sub- optimal and design costs are wasted Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 6
  7. 7. Cases of Failure in RE o How much library functions do you use? o New software development (less than 30% in the market) o How much mobile phone functions did you use? o ..... Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 7
  8. 8. Analysis Methods o System analysis – top down decomposition o Establish goal/functions representation in, e.g., data flow diagrams o Quick and dirty methods Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 8
  9. 9. Obstacles to RE o Tacit knowledge o Ambiguity o Attitude and opinions Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 9
  10. 10. Three Dimensions Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 10
  11. 11. Four Worlds Framework Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 11
  12. 12. User Requirements Framework o User Context and Early Design o Prototype and User Test o User requirements documentation Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 12
  13. 13. Users’ Limitation o Users do not have clear vision of what they want o Goal can be fuzzy o Do not know what is technical possibility o But,once they get, they can see how it can be improved .... or they simply do not like it Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 13
  14. 14. Requirement Types and Pathway o High level functions, towards the final goal o Detail functions o How functions should work o Constraint on system operation o Statement about performance o Implementation constraints Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 14
  15. 15. Requirement Types and Pathway o Functional requirements • The goals o Non functional requirements (NFR) • Quality • Performance • Environment issues • Cost • Time Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 15
  16. 16. Constraints o > are conditions or laws that the system will have to obey during operation or during design • Human cognitive • Physical • Environmental • Costs • Legal Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 16
  17. 17. User Requirements Documentation o General system characteristics o Organizational structure o Tasks scenario and interaction steps o Technical environment o System functions and features o User interface design o User support o Physical environment Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 17
  18. 18. User Requirements Documentation o Social and organizational environment o Standards and styleguides to apply o Test plan Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 18
  19. 19. Documentation o Natural language? o Technical language? o Long, dense text? Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 19
  20. 20. Documentation o Structure standards (IEEE 830, Mazza et al 1994) • Natural language, but short and avoid ambiguity • Structured, defined items • Management tools for diagram • Categorize stakeholders and different requirements Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 20
  21. 21. User Context and Early Design o Identify users and stakeholders, and their characteristics o Describe technical/physical/social and organization environment o Review: current process, similar systems and products o Perform expert review of design Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 21
  22. 22. RE Tasks and Processes o No “cook book”, but “roadmap” o Dynamically: pre-design and within design process o Common methods: • Interview • Observation • Questionnaires • Text and document analysis o Set Scope and Bainstoming Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 22
  23. 23. User Requirement Methods o Functionality Matrix o Storyboarding o Task analysis o Task allocation Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 23
  24. 24. Functionality Matrix o This method is useful when the number of possible function is high Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 24
  25. 25. Goal Analysis o Goal hierarchy and decomposition • e.g. Final goal: Increase customers’ satisfaction • Reduce processing time for constraint • Improve personal service in ordering • Reduce lead time for delivery Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 25
  26. 26. Events Analysis o Outcome is to scope the system in terms of its input, output, and major functions o Object oriented: focus on event o Event process chains • Where does the output from the process go to? • What process or fuction is responsible for responding to this even? • Who or what is the destination of this even and why do they want it? • Input-Process-Output (IPO) charts Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 26
  27. 27. Modeling o Analysis + Modeling = elaborate requirements o Different methods • Semantic model • Conceptual model • Process/information flows • Data flow diagram • Data structures • Entity Relationship Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 27
  28. 28. Faculty of Engineering - Universitas Indonesia Requirement Engineering (part 2) Kalamullah Ramli Electrical Engineering Department
  29. 29. Basic Objectives of RA o To delineate the data requirements of the enterprise in terms of basic data elements o To describe the information about the data elements, and the relationships among them needed to model these data requirements o To determine the types of transactions that are intended to be executed on the database, and the interaction between the transactions and the data elements Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 29
  30. 30. Basic Objectives of RA o To define any performance, integrity, security, or administrative constraints that must be imposed on the resulting database o To specify any design and implementation constraints, such as specific technologies, hardware and software, programming languages, policies, standards, or external interfaces o To thoroughly document all of the proceeding in a detailed requirement specification o Data element can also be defined in a data dictionary system, often provided as an integral part of the database management system Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 30
  31. 31. i* Family of Model Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 31
  32. 32. Validation o User’s understanding of the requirement specification o User agree that it accurately reflect their wishes o Different prototypes and scenario are normally used Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 32
  33. 33. Verification o Requirement specification behaves correctly and does not violate any of the laws specified by the users Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 33
  34. 34. Boundary o The system built behaves correctly (verification) o The system output makes sens to the user (validation) o However, boundary can be blurred Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 34
  35. 35. Balance the Requirements o Different stakeholders have different requirements o Trade-off analysis methods, decision making table, models, relationship maps, etc Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 35
  36. 36. Conduct Negotiation o Structure options and choices o Establish judgment criteria o Explain the options o Vote? o Diagnose the cause of disagreement Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 36
  37. 37. Conflicts o Probably due to lack of shared understanding • Handling personal attach – steering sensitive topics away from them • Blocking: challenge those who said: “it won’t work ...”, “it can’t be done .... “ • Trade-off between NFR • Test Assumptions • Benefit Analysis Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 37
  38. 38. Trade-off Between NFR o Quality vs Delivery time o Cost vs Development time o Security vs Access o Functional vs Usability, Complexity Reliability, and Maintainability Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 38
  39. 39. Functional Allocation o Automated or Manual o Management Level o Operational Level o Some Guidelines • Machine: repetitive processing, high volume data processing, monitoring, deterministic tasks • Human: recognition, reasoning, flexible, problem solving, non-deterministic tasks and unpredicted events Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 39
  40. 40. Initial Pathways and Scoping for Requirements o Policy-, or business-driven o Problem-initiated o Technical Driven o External Environment Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 40
  41. 41. Policy-, or Business-Driven o Business, social-economical theories o Williamson 1980 theory: predict the type of organizational relationship according to the goods that a customer wants to acauire from a supplier o Top-down decomposition Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 41
  42. 42. Problem-initiated o Existing system has problem o Event-based analysis • Event-tree analysis • Failure mode-event analysis • Cause-effect net o Model-based analysis Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 42
  43. 43. Technical-driven o User’s immediate goals is often to acquire new technology o User’s work goal analysis o Fit the new technology with existing system o Demon the functions of the new technical Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 43
  44. 44. Applications & Technology Factors Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 44
  45. 45. External Environment o NFR • Safety • Security • Accessibility • Usability o Market Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 45
  46. 46. Conversation o Rasmussen’s Framework (1986) Communication is generally an automatic and hence skilled process so it is prone to slip- and lapse- error in failure to listen and poor generation Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 46
  47. 47. Conversation o Discourse theory (Clark 1996) • People communicate to establish and achieve shared goals • Motivated by purpose • Cylce of exchanges • Common ground of understanding o Discourse: is the branch of linguistics that investigates how meaning is derived in context Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 47
  48. 48. Conversation and Context o Meaning is often constructed by the context of conversation • Role of speakers • Place • Time o Shared belief o Shared externally perceivable entities Electrical Engineering Dept.– Faculty of Engineering, Universitas Indonesia 48

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