Server-and-Client-System

This project is basically an implementation of Server and Client System, based on signals communication and transferring data through files.

in this project, we implement a server, which represents a simple calculator, that supports 4 basic operations: add, substraction, multiply and division.
The server gets from the client 2 numbers, and one of the requested operations.
The server calculates, and returns to the client the result.

How Does it Works?

• The server is running at the background, so it can get any client request at any time.
• Client's request signals to the server, so the server can manage the request.
• By using "ps" command, we get the server PID. we should keep its PID, in order to communicate between clients and the server along the program (works instead of using URL).
• Several client programs must be run at the same time.
• Each client request will get 4 arguments, as the following:
  ex4_client.out P1 P2 P3 P4
  While Pi means:
  • P1 is the server PID (stays constant for the whole program run).
  • P2 is the first number.
  • P3 is the operator we use: 1 for add, 2 for substraction, 3 for multiply and 4 for division.
  • P4 is the second number.

For example:
ex4_client.out 1234 70 2 30
We can see that the client wants to connect to a server with PID 1234, and wish to calculate 70-30.
The server should return 40 as a result, back to the client.

• Once the server gets a signal from a client, the server creates a child proccess, so its job is to manage the client request, so the father proccess can wait for another signals of another clients.
• The client is waiting for a result from the server, but the client is not patient, so if client is waiting over 30 sec to a result, then we print "Client closed because no response was received from the server for 30 seconds".
• Otherwise, the client gets the result from the server in time, and prints the result to the screen. Then the client closes all his files.
• We should also notice that if the server doesn't get any request from clients for over 60 sec, the server stops running and prints: "The server was closed because no service request was received for the last 60 seconds".

Example of compiling and running: