Midterm Examination

CSci 555 / Neuman Fall 1993
Directions for completing exam

Answer the following two - three part questions:

1. (55 points for 3 parts) You have been hired by the Clinton administration to help Al Gore reinvent government. An important point in the program is to introduce modern computing practice to the government and to integrate government offices into the evolving national information infrastructure. Your task is to design a new distributed information system for the federal government. Among other things, this system will be used to:
   • Manage supplies for all government agencies.
   • Issue payments to government employees, contractors, and vendors.
   • Support electronic mail between government workers and the public.
   • Disseminate information to industry and the public.
   • Store information about citizens needed to calculate taxes and entitlements payments.

   Answer the following questions about the design of such a system.

   1. What are the objects to be named in such a system? What information will be known when looking for an object? What naming mechanisms are appropriate for each of the objects you just identified? Why? (20 points)
   2. What are the requirements for synchronization in this system? What communication method(s) would you use (e.g., message passing, remote procedure call, shared memory, or work queue) to handle updates, queries, and commands. Discuss the reasons for your choice, comparing it with the alternatives. Be sure to mention any negative implications of your choice. (15 points)
   3. What information must be protected in this system? Who will be allowed to access this information? What steps might you take to protect this information in the design of the system (don't forget to think about the overall design, not just the security mechanisms themselves)? Justify your answer. (20 points)

2. (45 points) The recently announced merger between Bell Atlantic, a regional phone company, and Tele-Communications Inc (TCI), the largest cable company in the United States, has caused much speculation regarding the kinds of services that will soon be available through the merger of the telecommunications, computer, and entertainment industries.

   Pending approval of the merger by the federal trade commission, you have been hired by the TCI-Atlantic to develop their information delivery architecture. This architecture will support the distribution of television programs and other information to groups of customers. It must support pay-per-view and on-demand access to programs. You expect that Judge Greene will order that the architecture also support access to programming provided by independent information and entertainment services. Because of the large number of services, it must be possible to tailor the services available to the needs and preferences of individual customers.

   For your design, answer the following questions:

   1. What information is maintained in the system? For each type of information where is it best kept: on equipment owned by the information provider (the source), on computers owned by TCI-Atlantic, or on equipment owned by the customer. If on equipment owned by TCI-Atlantic, where should the equipment be located? Justify your answer. (15 points)
   2. What communication method(s) are you likely to use in such a system. Why? (10 points)
   3. How would you support pay-per-view? How could independent information providers be assured that they are paid for the use of their programs? Does your solution absolutely prevent theft-of-service? If so, why? If not, how might it be defeated? (20 points)

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