C++ :: Two Way Event-driven Communication Between Objects

I need to implement a two-way asynchronous communication between two objects, not using any IPC.

What I have now is a producer-consumer model where producer sends a number "88" to consumer at random intervals. Now, I need consumer to send a number "99" back to producer at a random intervals, this probably should be done in a separate thread.

I am using GNU on Linux, here is the compile line.

Code:

g++ -g -std=c++11 main.cpp -o main

Code:

#include<iostream>
#include<chrono>
#include<thread>
class IObject {
public:
virtual void fromApp(int i) = 0;
virtual int toApp(int& i) = 0;// ???

[code].....