Goal #

Write 2 programs, client and server, that communicate via POSIX message queues.

The server program creates 3 message queues with names PID_s, PID_d and PID_m where PID is the server process ID. The server program prints the names of all queues to stdout.

The server waits for data in any of its queues, receiving a client PID and two integers. Then, computes the result: sum for PID_s queue, division for PID_d, and modulo for PID_m. The result is sent to the corresponding client queue (see below). The server should not terminate if the client queue is unavailable. After receiving SIGINT the server destroys its queues and terminates.

The client process is called with a single argument: the name of the server queue. The client creates its own queue (the name is the client’s PID) and continues to read lines containing two integers until it encounters EOF. After receiving a line the client sends a message containing its PID and the two integers to the server queue and waits for a reply. The reply is displayed on stdout. If the reply does not arrive within 100 ms, the program terminates. While terminating, the program destroys its queue.

Stages #

1. The server creates its queues and displays the names of the queues. After 1 second, it destroys those queues and terminates. The client process creates its own queue, waits for 1 second, destroys its queue, and terminates.
2. Server reads the first message from PID_s queue. Sends the first answer back to the client. Ignores all errors. The client reads 2 integers from stdin and sends a single message to the server. It waits for the result and displays it.
3. The server handles all queues and calculates the proper results. Terminates at SIGINT. The client sends the messages until EOF is read or reply timeout occurs.
4. The queues should be removed on program termination. Full error handling.