Problem of md5sum warning when web is refreshed

[dwlee]

When web client using roslibjs is refreshed, md5sum warning is occurred. And then the refreshed client can not publish topic for about some second.

The situation is as below.

1. Launch rosbridge.
   roslaunch rosbridge_server rosbridge_websocket.launch --screen
2. Load test client 1 html (It is simple html page. it just publishes /chatter message which is std_msgs/String type).
3. Load test client 2 html (it only subscribe message sent client 1).
4. Send the string message by /chatter in client 1.
5. Check received message in client 2 side.
6. If you check the received message, and refresh the client 2. The md5sum warning will be happened as below. Try to publish again at client 1, but client 2 can not receive message for a little while .

[WARN] [WallTime: 1412842915.168814] Could not process inbound connection: [/rosbridge_websocket] is not a publisher of [/chatter]. Topics are [['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n\n', 'callerid': '/rosbridge_websocket', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/chatter', 'type': 'std_msgs/String'}

This is my test code.
https://github.com/robotics-in-concert/rocon_demos/tree/office_concert/office_web_interface/www/web_app/yujin_office/test_app

test_pub.html is client 1 and test_sub.html is client 2. If push the chatterbutton client 1 publish the simple string included count message.

[rctoris]

Can you provide your example code?

[dwlee]

I updated the url

[jihoonl]

The issue is that rosbridge unregiesters and reestablishs the publisher with same topic name every page refresh. It has caused some topic msg loss when the newly fresh page starts to publish immediately.

The issue is actually the limitation of rospy but we wanted to share since it could be a common issue for web apps using rosbridge. Here is related rospy issue

[jihoonl]

To reproduce warning message only with rospy,

Terminal 1

> rostopic echo /chatter  # with roscore

Terminal 2 with this code

#!/usr/bin/env python

import rospy
import std_msgs.msg

if __name__ == '__main__':

    rospy.init_node("chatchat_pub")
    test_pub = rospy.Publisher('chatter', std_msgs.msg.String, queue_size=1)
    rospy.loginfo("Publishing")
    test_pub.publish('hola')
    rospy.loginfo("Done")
    rospy.sleep(1)
    rospy.loginfo("Unregistering...")
    test_pub.unregister()
    rospy.loginfo("Done")
    rospy.spin()

Then you will see below as a result.

jihoonl@whoola:~/research/ros/isolate/src/test$ ./test.py 
[INFO] [WallTime: 1414462063.709317] Publishing
[INFO] [WallTime: 1414462063.709492] Done
[INFO] [WallTime: 1414462064.710662] Unregistering...
[WARN] [WallTime: 1414462064.711620] Could not process inbound connection: [/chatchat_pub] is not a publisher of [/chatter]. Topics are [['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n\n', 'callerid': '/rostopic_32229_1414462060102', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/chatter', 'type': 'std_msgs/String'}
[INFO] [WallTime: 1414462064.712748] Done
[WARN] [WallTime: 1414462065.713453] Could not process inbound connection: [/chatchat_pub] is not a publisher of [/chatter]. Topics are [['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n\n', 'callerid': '/rostopic_32229_1414462060102', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/chatter', 'type': 'std_msgs/String'}
[WARN] [WallTime: 1414462067.716019] Could not process inbound connection: [/chatchat_pub] is not a publisher of [/chatter]. Topics are [['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n\n', 'callerid': '/rostopic_32229_1414462060102', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/chatter', 'type': 'std_msgs/String'}


[WARN] [WallTime: 1414462071.719720] Could not process inbound connection: [/chatchat_pub] is not a publisher of [/chatter]. Topics are [['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n\n', 'callerid': '/rostopic_32229_1414462060102', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/chatter', 'type': 'std_msgs/String'}
[WARN] [WallTime: 1414462079.727917] Could not process inbound connection: [/chatchat_pub] is not a publisher of [/chatter]. Topics are [['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n\n', 'callerid': '/rostopic_32229_1414462060102', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/chatter', 'type': 'std_msgs/String'}

[jihoonl]

A quick hack to prevent the problem is commenting out topic unregistration in rosbridge_library/pulibhser.py

311# if not self._publishers[topic].has_clients():
312#           self._publishers[topic].unregister()
313#            del self._publishers[topic]

[T045T]

Since several forks have adopted this "quick hack", and it doesn't look like rospy is going to fix the root cause any time soon (assuming it's possible to do so), how about a nicer solution?

I'm thinking a timeout for unregistering topics with no clients, so the publisher survives quick page reloads, but rosbridge doesn't leak publishers. This is particularly important in connection with the service-based tf2_web_republisher, as that will generate new topics for each new client (and as such, for each page reload).

If you think a timeout is an acceptable solution, I'll implement it :)

[jihoonl]

Yeah. I think it would be sufficient to keep it in the main stream with some explanation. Thanks @T045T

[salsalam]

I'm new to ROS and rosbridge. I am receiving these warnings and would like to prevent them. Is it still the case that I should adopt the "quick hack"? I am running 0.7.13 since I used sudo apt-get install ros-indigo-rosbridge... to install and that's what it gave me.

Thanks for any help you can provide.

[Sanic]

I'm interested in that too.
@T045T Did you manage to implement the Timeout yet?

[jihoonl]

This should be mitigated by #247

[jihoonl]

Otherwise, this is an issue in rospy not in rosbridge.

[paul-mesnilgrente]

Hi everyone,

I see that this is an old issue and it seems to be solved. However I have this message:

[WARN] [1511259980.900398]: Could not process inbound connection: [/rosbridge_websocket] is not a publisher of [/ui_action]. Topics are [['/text_to_speech', 'std_msgs/String'], ['/speech_to_text', 'std_msgs/String'], ['/rosout', 'rosgraph_msgs/Log']]{'message_definition': 'string data\n', 'callerid': '/rosbridge_websocket', 'tcp_nodelay': '0', 'md5sum': '992ce8a1687cec8c8bd883ec73ca41d1', 'topic': '/ui_action', 'type': 'std_msgs/String'}

I am using ros-kinetic on Ubuntu 16.04. Should I apply the quick fix or it has been added to the ubuntu package?

[gonzalocasas]

The unregister timeout is really not a sustainable solution. I am using rosbridge_server in a context that is not about quick reconnects like the webpage reload case that was mentioned in several of the linked issues, and this really makes it extremely inconvenient to use.

Any hope for a fix for the root cause at some point?