Internet Programming

Client/Server Using Sockets

Two Python scripts: one a server; the other a client that will use the server.

The loan function module is used.

Server

The server will listen on port 12321. It will carry out loan computations using the loan module.

Payment format: The request is a string beginning with capital ‘P’ and followed by an initial balance, a single space, an annual interest rate (in decimal), a single space and a number of months. Balance format: The request is a string beginning with capital ‘B” and followed by a month number, a single space, an initial balance, a single space, an annual interest rate (in decimal), a single space and the monthly payment For example, a payment request might be in the form

P10000 0.1 12

This is a loan with an initial balance of 10000, an annual interest rate of 10% and a term of 12 months.

A balance request might be in the form

B13 10000 0.1 879.1588723000987

This is for month 13 with an initial balance of 10000, an annual interest rate of 10% and a monthly payment of 879.1588723000987.

The server will create a response to the client for each request. The first character of the response will indicate the type of response:

‘E’ indicates an error response. The remainder of the response is an error message ‘B’ indicates a response to a balance request. The remainder of the response is the balance remaining on the loan at the end of that month (the remainingBalance function) ‘P’ indicates a response to a payment request. The remainder of the response is the monthly payment that will pay off the loan in the time specified. The response to the example payment request would be

P879.1588723000987

The response to the example balance request would be2

B-3.296918293926865e-11

Server Error Checking

The server responds properly in the case of an erroneous request.

Client

The client script will accept three command line arguments: the initial balance; the annual interest rate as a percentage; and, the number of months in the term of the loan.

Example: loan_client.py 10000 10 12

for a loan with an initial balance of $10,000 borrowed at an annual rate of 10% due in 12 months.

The client will send a payment request to the server with the given input parameters. Then, the client will take the payment amount and send to the server a balance request where the month number is one more than the term of the loan. The client should print the payment amount (suitably labeled) formatted to two decimal places. The client should print the balance amount (suitably labeled) as received.