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    Questions of Data Flow Diagrams

      Exercises on DFDs

    1. Describe an ERD and a DFD. How do they differ?
    2. Name the three types of icon in a DFD. How many types of icon in an ERD?
    3. If there is an arrow from one icon to another in a DFD, what does it mean?
    4. What are the Gane and Sarson icons?
    5. Here [ DFD1.gif ] is a first rough DFD. Redraw with the right boxes using the Gane & Sarson Notation.
    6. Correct a given DFD model. (Handout)
    7. What is shown on a context DFD of a system? Give an example.
    8. What is shown in a Level-0 DFD? Give a level-0 that refines your context DFD.
    9. How do you document the contents of data stores?
    10. How do you document the detailed processing of data?
    11. List a dozen rules that a valid DFD must follow.
    12. If you discover a person who does no more than reinput some previous output -- how can you improve the system?
    13. Name 6 bad DFD smells.
    14. What is the ultimate reason for storing data in a system?
    15. Draw a context DFD of:
      1. Your team project.
      2. my web site.
      3. CSUSB myCoyote
      4. CSUSB CSCI web site.

    16. Given the fish-eye level-0 DFD of a system draw the context DFD.
    17. Answer questions about a given DFD.
    18. List some strange ways that information/data is transmitted/stored in an enterprise that you know about.
    19. Draw an ERD showing the entities: Student, Teacher, Section, and Course. Show no attributes. Show some of the obvious relationships between the entities.
    20. Draw a simple ERD thyat shows a single entity type from your project and lists the data elements associated with the typeof object/entity.
    21. Take this diagram [ manufacturing.gif ] and redraw it as a DFD -- note: you can treat some money and material flows as data flows.

    22. Draw a simple but correct DFD...
    23. Given a Context DFD draw a plausible and correct level 0 fish-eye DFD.
    24. Given a process in a DFD draw a correct and plausible expansion/fish-eye DFD that would replace it.

      Exercise -- Context Diagram of a Possible Project

      What project would you like to work on this quarter? See ./projects0.html Draw a first rough context DFD of it. Draw a first rough ERD for it.

      Data Flows

      Draw a level 0 Data Flow Diagram (DFD) that fits the following system:
        Students login with an email Id and password and the system provides access to the schedule for the current quarter. Students pick classes and enrol in them. Enrolments are recorded in rosters. The system formats rosters for each class and sends them to teachers. Teachers can drop students on their rosters.

      The DFD should have more than one process, more than one source/sink and more than one data store. The words in bold in the above box should appear in your diagram at least once. You may have to invent some names.


  1. TBA::="To Be Announced".
  2. TBD::="To Be Done".


    Notes -- Analysis [ a1.html ] [ a2.html ] [ a3.html ] [ a4.html ] [ a5.html ] -- Choices [ c1.html ] [ c2.html ] [ c3.html ] -- Data [ d1.html ] [ d2.html ] [ d3.html ] [ d4.html ] -- Rules [ r1.html ] [ r2.html ] [ r3.html ]

    Projects [ project1.html ] [ project2.html ] [ project3.html ] [ project4.html ] [ project5.html ] [ projects.html ]

    Field Trips [ F1.html ] [ F2.html ] [ F3.html ]

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