ros2 simple message to rosbridge_suite

edit

on ros2 foxy( Ubuntu 20.04) I installed rosbridge

Through a web socket I created the topic three with that message.

{ “op”: “advertise”, “topic”: “/three”, “type”: “std_msgs/String” }

but failed send than sending a simple string with that

{ “op”: “publish”, “topic”: “/three”, “type”: “”, “msg”: “forward” }

or that

{ “op”: “publish”, “topic”: “/three”, “type”: “std_msgs/String”, “msg”: “forward” }

what would be the right way to post a simple text message ?