IS 313: Data Structures in Java

Autumn 2002

Individual Assignment 4

Client/Server implementation using sockets

Due Wednesday November 20 before 11:30pm

The classes CurrencyView and CurrencyAccess implement a simple currency exchange program and access the exchange database. They have been slightly modified from the currency programs presented earlier in the quarter. For this assignment, you will modify the CurrencyAccess class so that it acts as a client and obtains the currency information from a server called CurrencyServer. This server then obtains currency information from the database.

Your client/server program should work like the MultiTime program discussed in class. The MultiTime program is implemented with the TimeViewer, the MultiTimeClient and the MultiTimeServer classes. In particular, your program should be structured as follows:

• Your revised CurrencyAccess class should provide the same public methods. This way, the CurrencyView class does not need to be modified.
• The CurrencyAccess class should look up the server host name using a properties file called currency.properties. If this file does not exist, your program should use "localhost" as the server host name. See the MultiTimeClient class for an example.
• The CurrencyAccess class needs to send commands to the server so that it can retrieve the following:
  • The list of currency names
  • The amount in foreign currency when given the amount in dollars and the name of the foreign currency.
  • The amount in dollars when given the amount in a foreign currency and the name of the foreign currency.
• You will need to create commands so that your client can successfully communicate with your server. See the MultiTimeClient and MultiTimeServer classes for an example.
• Your CurrencyServer class can be implemented entirely using static methods (like the MultiTimeServer class).

Submission

Before the due date and time, you should submit the following files through the submission Web page:

• CurrencyAccess.java (the client class)
• CurrencyServer.java

  Since you do not need to modify CurrencyView class, you do not need to submit it.

If for some reason you are unable to submit the files, you may email me them as an attachment.