CS 677 Distributed Operating Systems

Spring 2005

Programming Assignment 1: A Centralized Bank Account Manager

Due: March 11th - in class

(for off-campus students - 14 days after viewing Lecture 8 )

1 The Problem

In this programming assignment you are to implement a Centralized Multi-User Concurrent Bank Account Manager. The system has two important components:

  1. Bank Server
    The server program that services online requests for account manipulations and maintains all customer records correctly.
  2. Clients
    Customers are clients of the bank server and use its services to update bank accounts. The operations that can be performed on an account are: withdrawl of an amount from an account and deposit of an amount into an account. Additionally, the bank server can have it's own service that periodically deposits an interest amount to each account based on some fixed rate.

An pictorial representation of the system is as shown in the figure below.

The components of the system and their functionalities to be implemented are as follows:
  1. Server
    The server receives queries from customers (ATM clients, Clients/Billing agencies performing online transactions etc.) for operations on accounts.
    The server should have the following functionalities:
  2. Client
    A client issues requests to the server from a transaction based on account numbers.
    Client functionality:

The purpose of this assignment is to get you familiarized with sockets/RPCs, processes, threads and synchronization.

You can be creative with this project. (like add create new online accounts, which means add new functionalities, other than mentioned above, at both client and server etc.)
You are free to use any programming languages (C, C++, Java, etc) and any abstractions such as sockets, RPCs, RMIs, threads, events, etc. that might be needed.

Some things to keep in mind:

2 Evaluation and Measurement

Demonstrate that your system works correctly according to requirements stated in the description of the system.

  1. Show that the server preserves correctness of transactions by deducting money only when available, is multi-threaded and accepts requests concurrently.
  2. Show use of locks/semaphores that protects simultaneous access to the same account. i.e., design a test experiment(s) to demonstrate this using logs or message display during events.
  1. Use a set of periodic requests at each client (e.g., each sending a request every 2 secs) and vary the number of clients connected to the server. Measure the average time to complete each transaction for each client. Plot a graph to show average time to complete each transaction as number of clients are increased (say from 1 to 100).
  2. The same experiment can be repeated by fixing the number for clients (to say 25) and then varying the request rate. i.e., one request every 0.1,0.2,...1 secs etc. Measure and plot the average time to complete each transaction as the request rate is varied.
These are guidelines only, so be creative in what can be evaluated and measured as part of your experiments to test the system.

3 What you will submit

When you have finished implementing the complete assignment as described above, put all the code in a separate directory in your edlab account (/677/project1).

You are required to submit your solution in the form of printouts.

Each program must work correctly and be documented. You should hand in:
  1. A copy of the output generated by running your program. When the sensor proxy receives data, have your program print a message "data received from source s" . When a sink is sent data by the proxy server, have your program print messages for the data being sent by the proxy and for the data being received by the sink.
  2. A separate (typed) document of approximately two pages describing the overall program design, a description of "how it works", and design tradeoffs considered and made. Describe clearly how multiple threads and synchronization are handled. Also describe possible improvements and extensions to your program (and sketch how they might be made).
  3. Prepare a list of design considerations you made while designing your system and describe each briefly. This is similar to the design considerations discussed in class of the Email system on the last slide of Lecture 2.
  4. A program listing containing in-line documentation.
  5. Instructions to compile and run the code from 677/project1.
  6. A separate description of the tests you ran on your program to convince yourself that it is indeed correct. Also describe any cases for which your program is known not to work correctly.
  7. Performance results.

    Let us not waste a lot of trees. So, if any of the above turn out to be large, just save the relevant information in a file, leave it on your EDLAB account and submit the name of the file.

    4 Grading policy for all programming assignments


    Grades for late programs will be lowered 12 points per day late.