How do I communicate between 2 robots ?

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As I am new to ROS, I don't know how to establish communication between 2 robots. I have launched 2 Husky robots in gazebo using namespace. The 2 robots must communicate with each other for data sharing, how do I do that? If data communication is not possible with Husky robots, then which robots should be used? My main aim is to implement Fog Computing algorithms here and check how the robots respond to it. Here I am simulating in Gazebo but if I have actual robots, then they must also communicate with each other. Through communication, I mean they can send their data to one another, process it and return back. I am using ROS-Indigo with Gazebo-2.2.2 on Ubuntu-14.04.