Exchanging messages between two C++ programs

Question

I am new to creating Windows applications in C++. My task is to write two cpp files, one of which will send a number (x) to the other one, the other one will evaluate f(x) and send it back to the first one. I should implement it using Messages. Couldn't get anything specific online, Could someone pls give me a clue, where to start? Great thanx!

Answer 1

Are you talking about window messages? If so, the sending app could use SendMessage , which would cause the receiving app to get its window procedure executed. Of course, this means that the receiving app needs to create a window whose window handle is somehow made available to the sending app.

Answer 2

You can do it in several ways.

• Using WM_COPYDATA message to pass the data
• Allocating global memory to pass data and sending your own message, such that second program can read the data from memory
• Sending a message (if two ints suit your needs to pass data)
• Using named pipes
• Using TCP/IP local connection (peer to peer or through a server)

Answer 3

Look at ZeroMQ (http://zeromq.org ; cross-platform, LGPL). It is a very simple, lightweight and powerfull library. From the very basic level you can use it to exchange UDP-style datagrams, but through reliable transport (TCP or some variants). Also you have cancelling support, time-based polling and advanced network schemes (which are non-needed in your case). I've selected it for a similar task, and it performs very well.