can't subscribe the message via rosbridge (websocket)

rosbridge

asked 2017-09-30 06:03:50 -0500

sasadasd
104 ●18 ●21 ●27

updated 2017-09-30 06:27:50 -0500

Hello,

I want to display the turtlesim_node's topic("/turtle1/cmd_vel") by using rosbridge.

to this end, I implement the following 3 codes.

[websocket.py]

#!/usr/bin/env python
import rospy, os
import SimpleHTTPServer
def kill():
  os.system("kill -KILL " + str(os.getpid()))

os.chdir(os.path.dirname(__file__) + "/../contents")
rospy.init_node("webserver")
rospy.on_shutdown(kill)
SimpleHTTPServer.test()

[index.html]

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />

<script type="text/javascript" src="http://cdn.robotwebtools.org/EventEmitter2/current/eventemitter2.min.js">     </script>
<script type="text/javascript" src="http://cdn.robotwebtools.org/roslibjs/current/roslib.min.js"></script>

<script type="text/javascript" type="text/javascript">
  // Connecting to ROS
  // -----------------

  var ros = new ROSLIB.Ros({
     url : 'ws://localhost:9000'
  });

  ros.on('connection', function() {
    console.log('Connected to websocket server.');
  });

  ros.on('error', function(error) {
    console.log('Error connecting to websocket server: ', error);
  });

  ros.on('close', function() {
    console.log('Connection to websocket server closed.');
  });


  // Subscribing to a Topic
  // ----------------------

  var listener = new ROSLIB.Topic({
    ros : ros,
    name :'/turtle1/cmd_vel',
    messageType :'geometry_msgs/Twist'
  });

  listener.subscribe(function(message) {
    console.log('Received message on ' + listener.name + ': ' + message.data);
    value1=message.data;
  });
</script>
</head>

<body>
  <h1>Simple roslib Example</h1>
  <p>Check your Web Console for output.</p>
</body>
</html>

[webtopic_turtle.launch]

 <launch>
 <node pkg="webtopic_turtle" name="webserver" type="webserver.py" args="8000" />
 <include file="$(find rosbridge_server)/launch/rosbridge_websocket.launch"> 
    <arg name="port" value="9000"/>
 </include>
 </launch>

After that , I executed catkin_make and "chmod +x webserver.py" in proper directory.

Finally, I executed the following command.

(1)roscore (2)roslanch webtopic_turtle webtopic_turtle.launch (3)open http://localhost:8000/ then the message is appeared in terminal that is executed webtopic_turtle.

[INFO] [WallTime: 1506767932.089070] Rosbridge WebSocket server started on port 9000 127.0.0.1 - - [30/Sep/2017 19:38:55] "GET / HTTP/1.1" 200 - [INFO] [WallTime: 1506767935.992950] Client connected. 1 clients total. [INFO] [WallTime: 1506767936.406980] [Client 0] Subscribed to /turtle1/cmd_vel

(4) rosrun turtlesim tutlesim_node (5)rosrun turtlesim turtleteleop_key

But, it is not display the message'Received message on …' in terminal that is executed webtopic_turtle. what is the problem ? I confirm the rqt_garph and it showed the diagram that is properly subscribed the message"/turtle1/cmd_vel" in rosbrideg_websocket.

Please let me know if you can find how to resolve the problem. image description