ltng:sendMessage

Passes a message between two components.
To send a message, specify a string of text that you want to pass between components. Optionally, specify a channel for this event so that your components can select if they want to listen to particular event messages
sendMsg: function(component, event) { 
 var sendMsgEvent = $A.get("e.ltng:sendMessage"); 
 sendMsgEvent.setParams({
          "message": "Hello World", 
          "channel": "AccountsChannel" 
 }); 
 sendMsgEvent.fire(); 
}
Attribute Name Type Description
message String Required. The text that you want to pass between components.
channel String Specify this field if you want particular components to process some event messages while ignoring others.