如何使应用程序发送不知道接收方应用程序IP地址的消息？

Question

I've got 3 programs,

1. A client which sends a file,
2. A web application which receives the file and sends messages, and
3. A GUI which receives the messages from the web application.

The web application doesn't know the IP address of the GUI, so i suppose it will send the message to a port. The GUI knows the IP address of the web application and the port and listens all the time for incoming messages.
I tried to make the GUI client and the web application client but without success. Any suggestions how can i make the GUI program to listen for messages and the web application to send messages? I would really appreciate if you paste me some code because I'm new in programming.
Thanks.

Answer 1

If the GUI knows the address of the web application, but not vice versa, then it's the web application that should listen for connections. When the GUI starts, it should connect to the web application. The web application should receive this connection, remember it, and allow several connections at once (several GUIs running at the same time). Whenever there's somthing to report, the web application should report to all the connections it has remembered, and if there's any error sending the message, close and forget exactly the single connection that caused the error.

But to be honest, if you're serious about

paste me some code because i am new in programming

then you shouldn't be starting with client/server software and inter-process communication.