How to create a node to share data between different robots

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if i understand correctly you can use ros network and create a network in your main pc and other robot connect on ros master in main pc and they can subscribe or pubish data over network

If I understand you correctly, you want to make a node which automatically 'detects' the number and type of robots connected to a ROS network. This node can then, knowing the type of the robots, publish on the correct topics to control them?

You can easily make a node which will subcribe/publish to different topics with different message types as needed, this is used in many nodes already.

Can you define exactly what type of information will be shared between the robots?

UPDATE:

Okay to share position information between a group of robots should be fairly straightforward. As long as the robots are estimating their positions in the same coordinate system / map. Most of the localisation systems I've seen in ROS publish the estimated location of a rover using the TF system, if you had a configuration parameter which listed the TF frames which correspond to the rover positions then each robot could use TF lookups to find the position of all the other robots. There is no need for any publishers, subscribers or custom types.