WebsocketROSClientPython

WebsocketROSClientPython is a lightweight ROS package and Python library to messaging between the machines with ROS via websocket. You can subscribe and publish and call service messages between rosbridge server and client.

Data is transmitted in JSON format and automatically converted into ROS messages using the library rospy_message_converter

Server: ROS --> Bridge: JSON <-- Client: ROS/MATLAB/UNITY

Support:

• Publish
• Subscribe (messages are immediately published in the specified topic)
• Service (call only, the response didn't parse)

Note that this needs install:

sudo pip install websocket-client
sudo apt install ros-$ROS_DISTRO-rospy-message-converter
sudo apt install ros-$ROS_DISTRO-rosbridge-server

Stage: In the development

Usage

Init websocket client:

    from rospy_websocker_client import WebsocketROSClient as ros_ws
    ws_client = ros_ws('128.0.0.1', 9090) # ip, port, name of client
    ws_client.connect()

Disconnect:

    ws_client.disconnect()

Subscribe to topics from server:

    from geometry_msgs.msg import  PoseStamped
    # 1. The name of the topic server;
    # 2. The type of topic
    # 3. The name of the topic where to publish
    # 4. Frame rate: default = 0
    # 5. queue_length:  default = 0

    ws_client.subscribe('/position', PoseStamped(), '/position')

Publish to server:

    
    from std_msgs.msg import String
    msg = String()
    msg.data = "Test message"
    # 1. the name of the topic on server where to publish; 
    # 2. the message
    ws_client.publish("/client_topic",msg)

Call service from server

   # 1. the name of the service on server where to call;
   # 2. the service request message 
   ws_client.call_service('/ropic_of_service', srv_pub)