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Sample Questions for the Mid-Term Exam


  1. Indicate whether each of the following statements is true or false:

    _____ Sequence and collaboration diagrams show the interactions between classes.
    _____ The system is never an actor in a use case diagram.
    _____ A use case diagram with fine granularity will tend to have a large number of use cases for the amount of functionality in the system.
    _____ The waterfall life cycle describes a temporal progression.

  2. Choose the best answer to each of the following:

    _____ Which of the following is a type of UML diagram:
    1. Collaboration
    2. Context
    3. User Interface
    4. None of the above
    _____ A system consists of:
    1. A set of objects
    2. The attributes of objects
    3. The relationships between objects
    4. All of the above
    _____ An element/atom in a system is treated as:
    1. A stakeholder
    2. A life-cycle
    3. A black box
    4. None of the above
    _____ Requirements can be recorded using:
    1. Natural language
    2. Formal methods
    3. Both of the above
    4. Neither of the above

  3. Briefly define each of the following terms:

    Encapsulation



    Generalization



    Use Case



    Analysis



    Model



    Polymorphism



  4. Discuss the ways in which products can be categorized.

  5. Discuss the differences between needs and requirements (as we have used these terms in this course).

  6. Carefully:
    1. Interpret/explain the following model of a computer:

    2. Interpret/explain the following model of a computer:

    3. Discuss which of these two models is better and why.

  7. The following model describes my current address book:
    1. Carefully interpret/explain this model.

    2. How can this model be improved?

    3. Build a new model that allows for people to be members of an organization. (Note: The organization should have one address and everybody associated with that organization should have that address. The organization may have a central phone number and email address and everybody associated with the organization may have one as well.)

  8. Create a Use Case Diagram (in UML) for the following description of an Internet auction system:
    1. Types of users
      1. Anyone
        1. Anyone may use the search features of the system.
        2. Anyone may look at an auction's information.
      2. Members
        1. Only members may bid or place items for sale.
        2. All members must register with the system.
        3. Members must supply their name and a valid e-mail address.
        4. After registering, the system will create an account for the member.
          1. A password will be mailed to the e-mail address specified.
        5. Members must log in to bid or place an item for sale.
        6. Members who forget their password can have it re-mailed to them.
    2. Auctions
      1. An auction involves an item, a seller, and zero or more bidders.
      2. Items and sellers
        1. Sellers put up items for auction
        2. The item must include a name, a closing time, and a minimum bid.
        3. The item may include a description and a picture.
        4. Sellers may have any number of auctions active at one time.
      3. Bids and bidders
        1. Any member may bid in any auction.
        2. Bids may be placed at any time before the closing time.
        3. A bid must be at least the minimum bid, and higher than any bid so far.
      4. Ending an auction.
        1. No matter how an auction ends, it is immediately removed from the list of active auctions.
        2. If no bids are placed before the closing time, the auction is closed unsuccessfully and the seller notified by e-mail.
        3. If at least one legal bid has been placed before the closing time, the auction is closed successfully. The winning bidder and the seller are both mailed each other's contact information and the winning bid.
        4. The seller may cancel the auction up to 24 hours before the closing time. All bidders on this auction will be mailed a notice of the cancellation.
    3. Searching
      1. Any user may search through active auctions by keyword.
      2. All active auctions with name or description containing the keyword are presented to the user.
        1. The auctions are sorted by closing time in chronological order.
        2. The user may click a link to go directly to the auction.

    Create a use case diagram for this system.

  9. The following is a state diagram for the new cash registers being developed by "Quick-E-Mart".

    1. There is a major problem with this state diagram. What is it?

    2. How would you fix this problem? (You may modify the above diagram or draw a new one.)

  10. Convert the following collaboration diagram to a sequence diagram.

  11. Create a state diagram for the Windows-NT login system. Assume that the user is given three attempts to properly enter her/his password.

  12. In the following system:
    • The garage experiences the following events:

      mode-XXX: the operator sets the garage control mode to XXX (off, auto, closed, open).

      exitgate: an exit gate signals that a car has left.

      entrygate: an entry gate signals that a car has entered.

    • The garage counts the number of cars it holds (count), and knows its maximum capacity (max).
    • The entry gates should be locked in closed mode; unlocked in open mode; are in no particular state in off mode; and in auto mode, should be locked if the garage is full.
    • The operator may set any mode at any time.

    1. Indicate whether each of the following statements is true or false:

      _____ The full sign will only be lit when the garage is full.
      _____ This garage has 2 concurrent states when centrally controlled, one manual and one automatic.
      _____ On the transition labelled exitgate [count<max], the condition is redundant.
      _____ The diagram accurately represents point 3 of the problem.
      _____ The diagram accurately represents point 4 of the problem.
      _____ A start state is unnecessary for the nested Manual state.

    2. Does this statechart diagram eliminate the need for a class model?

Department of Computer Science

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