Installing, Running, and Using RosBridge

Introduction

This section describes installing RosBridge, which is useful for communicating to devices which do not have ROS installed (like windows machines with custom drivers)

Installing, Running, and Using RosBridge

from here and here

Install necessary prerequisites on the ROS machine

#Install rosbridge on guest machine
sudo apt install -y ros-melodic-rosbridge-suite

## ensure you have the most recent version of pip
pip3 install --upgrade pip

#Install roslibpy client for rosbridge on guest machine
pip3 install setuptools_rust service_identity roslibpy

#launch rosbridge server
roslaunch rosbridge_server rosbridge_websocket.launch

#open up your favorite python editor
spyder3

start roscore on the guest:
```
roscore
```

Run an existing talker in ROS. in a new terminal window:

cd ~/catkin_ws
source ./devel/setup.bash

#In the last tutorial we made a publisher called "talker". Let's run it:
#rosrun beginner_tutorials talker      (C++)
rosrun beginner_tutorials talker.py  # (Python)

Non-ROS machine setup

install roslibpy (required if you did not do this in the prior step)
```
pip install service_identity roslibpy
```

create a file called listener.py, substituting the ip address of the ROS Master for . Paste in the following:

# -*- coding: utf-8 -*-
"""
Created on Fri Mar 27 08:33:41 2020

@author: danaukes
"""

from __future__ import print_function
import roslibpy

client = roslibpy.Ros(host='<IPADDRESS>', port=9090)
client.run()

listener = roslibpy.Topic(client, '/chatter', 'std_msgs/String')
listener.subscribe(lambda message: print('Heard talking: ' + message['data']))

try:
    while True:
        pass
except KeyboardInterrupt:
    client.terminate()
except Exception as e:
    print(e)
    client.terminate()

Run from the editor(f5) or, in a new terminal window, navigate to the location of ’listener.py’ and type:
```
python3 listener.py
```

Now, create a file called talker.py, substituting the ip address of the machine for if on the host machine, or ’localhost’ if in the guest machine. Paste in the following:

# -*- coding: utf-8 -*-
"""
Created on Fri Mar 27 08:36:13 2020

@author: danaukes
"""

import time

import roslibpy

client = roslibpy.Ros(host='<IPADDRESS>', port=9090)
client.run()

talker = roslibpy.Topic(client, '/dancustom', 'std_msgs/String')

while client.is_connected:
    talker.publish(roslibpy.Message({'data': 'Hello World!'}))
    print('Sending message...')
    time.sleep(1)

talker.unadvertise()

client.terminate()

on the guest machine, start a new terminal window, and type
```
rostopic echo /dancustom
```