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Chapter 3

Requirements Modeling. Chapter 3. Phase Description. Systems analysis is the second of five phases in the systems development life cycle (SDLC) Uses requirements modeling and enterprise modeling to represent the new system

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Chapter 3

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  1. Requirements Modeling Chapter 3

  2. Phase Description • Systems analysis is the second of five phases in the systems development life cycle (SDLC) • Uses requirements modeling and enterprise modeling to represent the new system • Before proceeding to the next phase, systems design, you will consider system development strategies

  3. Introduction • This chapter describes requirements modeling techniques and team-based methods that systems analysts use to visualize and document new systems • The chapter then discusses system requirements and fact-finding techniques, which include interviewing, documentation review, observation, surveys and questionnaires, sampling, and research

  4. Systems Analysis Phase Overview • Systems Analysis Skills • Analytical skills • Interpersonal skills • Team-Oriented Methods and Techniques • Joint application development (JAD) • Rapid application development (RAD)

  5. Joint Application Development • User Involvement • Users have a vital stake in an information system and they should participate fully • Successful systems must be user-oriented and users need to be involved

  6. Joint Application Development • JAD Advantages and Disadvantages • More expensive and can be cumbersome • Allows key users to participate effectively • When properly used, JAD can result in a more accurate statement of system requirements, a better understanding of common goals, and a stronger commitment to the success of the new system.

  7. Rapid Application Development • Is a team-based technique that speeds up information systems development and produces a functioning information system • Relies heavily on prototyping and user involvement • Project team uses CASE tools to build the prototypes and create a continuous stream of documentation

  8. Rapid Application Development • RAD Objectives • To cut development time and expense by involving the users in every phase of systems development • Successful RAD team must have IT resources, skills, and management support • Helps a development team design a system that requires a highly interactive or complex user interface

  9. Rapid Application Development • RAD Advantages and Disadvantages • Systems can be developed more quickly with significant cost savings • RAD stresses the mechanics of the system itself and does not emphasize the company’s strategic business needs • Might allow less time to develop quality, consistency, and design standards

  10. Modeling Tools and Techniques • Functional Decomposition Diagrams • A top-down representation of business functions and processes • Also called structure charts

  11. Modeling Tools and Techniques • Functional Decomposition Diagrams Figure 3-9

  12. Modeling Tools and Techniques • Unified Modeling Language • A widely used method of visualizing and documenting software systems design • provides various graphical tools and techniques, such as use case diagrams and sequence diagrams

  13. Modeling Tools and Techniques • Unified Modeling Language Figure 3-10

  14. Modeling Tools and Techniques • Unified Modeling Language Figure 3-11

  15. Modeling Tools and Techniques • Unified Modeling Language Sequence Diagram Figure 3-13

  16. System Requirements Checklist • System requirement • Five general categories • Outputs • Inputs • Processes • Performance • Controls

  17. Future Growth, Costs, and Benefits • Scalability • A scalable system offers a better return on the initial investment • To evaluate, you need information about projected future volume for all outputs, inputs, and processes

  18. Future Growth, Costs, and Benefits • Total Cost of Ownership • In addition to direct costs, systems developers must identify and document indirect expenses that contribute to the total cost of ownership (TCO) • Microsoft has developed a method for measuring total costs and benefits, called Rapid Economic Justification (REJ)

  19. Fact-Finding • Overview • Although software can help you to gather and analyze facts, no program actually performs fact-finding for you • The first step is to identify the information you need

  20. Fact-Finding • Who, What, Where, When, How, and Why? Figure 3-15

  21. Fact-Finding • The Zachman Framework • A model that asks the traditional fact-finding questions in a systems development context

  22. Interviews • Systems analysts spend a great deal of time talking with people • Much of that time is spent conducting interviews • Consists of 7 steps

  23. Other Fact-Finding Techniques • Document Review • Observation • Seeing the system in action gives you additional perspective and a better understanding of the system procedures • Plan you observations in advance • Hawthorne Effect

  24. Other Fact-Finding Techniques • Questionnaires and Surveys • Keep the questionnaire brief and user-friendly • Provide clear instructions that will answer all anticipated questions • Arrange the questions in a logical order, going from simple to more complex topics

  25. Other Fact-Finding Techniques • Sampling • Systematic sample • Stratified sample • Random sample • Main objective of a sample is to ensure that it represents the overall population accurately

  26. Other Fact-Finding Techniques • Research • Newsgroups • Site visit Figure 3-23

  27. Other Fact-Finding Techniques • Interviews versus Questionnaires • When you seek input from a large group questionnaire is a very useful tool • If you require detailed information from only a few people, then you probably should interview each person • Interview is more familiar and personal • Questionnaire gives many people the opportunity to provide input and suggestions

  28. Documentation • The Need for Recording the Facts • Record information as soon as you obtain it • Use the simplest recording method • Record your findings in such a way that they can be understood by someone else • Organize your documentation

  29. Preview of Enterprise Modeling • At the conclusion of requirements modeling, systems developers should have clear understanding of business processes and system requirements • The next step is to model the logical design of the system

  30. Chapter Summary • The systems analysis phase includes three activities • The main objective is to understand the proposed project and build a solid foundation for the systems design phase • The fact-finding process includes interviewing, document review, observation, questionnaires, sampling, and research.

  31. Chapter Summary • Systems analysts should carefully record and document factual information as it is collected, and various software tools can help an analyst visualize and describe an information system • Chapter 3 Complete

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