connecting to external server

[melnarte]

Summary. Error during publisher-listener between local (virtual machine with kinetic) and remote (server Digital Ocean with melodic) hosts

Expected Result

Successful communication publisher-listener between local and remote hosts

Actual Result

artem@ubuntu16:~$ python talker.py Traceback (most recent call last): File "talker.py", line 7, in client.run() File "/home/artem/.local/lib/python2.7/site-packages/roslibpy/ros.py", line 83, in run raise Exception('Failed to connect to ROS') Exception: Failed to connect to ROS

Reproduction Steps

(1) start rosbridge on Digital Ocean server and start basic listener after (2) start rosbridge on localhost (3) run basic talker on localhost

import time

import roslibpy

client = roslibpy.Ros(host="http://167.172.173.63", port=9090)
client.run()

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

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

talker.unadvertise()

client.terminate()

System Information

(localhost) virtual box with ubuntu 16 and ROS kinetic (digital ocean host) ubuntu 18.04 with ROS melodic

[gonzalocasas]

You need to remote the http:// part of the host parameter, it's a websocket connection, so we use the host and port to build a URL like ws://167.172.173.63:9090, but in your case, it's resulting into ws://http://167.172.173.63:9090 which is invalid.

[gonzalocasas]

I'll close this, as it is most definitely a mistake in the host that was specified, however, feel free to keep commenting if you are still unable to get it to work.