Unable to publish message to ROS Bridge from Unity [closed]

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Hello,

I am trying to follow example from the submodule developed here which is a git submodule of unityros I was checking my interface by sending string message, however, my final intention is to send an array of float values coming from slider position I have.

I did have success in receiving messages from ROS side using the rosbridge by subscribing to the topic. But the other way round I cannot understand why this is not working.

Presently I am trying this:

#if UNITY_EDITOR
    void Start(){

        ros = new ROSBridgeLib.ROSBridgeWebSocketConnection("ws://192.168.142.67", 9090);
        ros.AddPublisher(typeof(ROSCommsSlider));           
    }
#endif
#if UNITY_EDITOR
    private void OnApplicationQuit(){
        if (ros != null) {
            ros.Disconnect();
        }
    }
#endif

#if UNITY_EDITOR
    public void my_func() {

    }
#endif

    // Update is called once per frame
    void Update() {
#if UNITY_EDITOR
        if (Input.GetKeyDown(KeyCode.C))
        {
            ros.Connect();
        }

        //ros.Render();
        ROSBridgeLib.std_msgs.StringMsg ms = new ROSBridgeLib.std_msgs.StringMsg("checking_connection");
        ros.Publish(ROSCommsSlider.GetMessageTopic(), ms);
#endif
}

my ROSCommsSlider looks like this:

public class ROSCommsSlider : ROSBridgeLib.ROSBridgePublisher {
    // my class for sending message to ROSbridge
    public static string GetMessageTopic()
    {
        return "/joint_values";
    }
        public static string GetMessageType()
    {
        return "std_msgs/String";
    }

    public static string ToYAMLString(ROSBridgeLib.std_msgs.StringMsg msg)
    {
        return msg.ToYAMLString();
    }

    public new static ROSBridgeMsg ParseMessage(JSONNode msg)
    {
        return new ROSBridgeLib.std_msgs.StringMsg(msg);
    }

}

When I run the ros bridge, for some reason it is creating 3 client connection instance, but however, it doesn't send in the string to my topic when I do:

rostopic echo /joint_values

I made sure I am sending this string as per rosbridge protocol

 Sending {"op": "advertise", "topic": "/joint_values", "type": "std_msgs/String"}

UnityEngine.Debug:Log(Object)
ROSBridgeLib.ROSBridgeWebSocketConnection:Run() (at Assets/ROSBridgeLib/ROSBridgeWebSocketConnection.cs:195)

and an error:

InvalidOperationException: The current state of the connection is not Open.
WebSocketSharp.WebSocket.Send (System.String data)
ROSBridgeLib.ROSBridgeWebSocketConnection.Publish (System.String topic, .ROSBridgeMsg msg) (at Assets/ROSBridgeLib/ROSBridgeWebSocketConnection.cs:264)
ROSCommsMain.Update () (at Assets/Scripts/ROSCommsMain.cs:73)

which I don't understand why as under my rosbridge shows: Clients Connected.

Additionally, I receive this Null Reference Issue when close the unity editor play.

NullReferenceException: Object reference not set to an instance of an object

ROSBridgeLib.ROSBridgeWebSocketConnection.Disconnect () (at Assets/ROSBridgeLib/ROSBridgeWebSocketConnection.cs:170)
ROSCommsMain.OnApplicationQuit () (at Assets/Scripts/ROSCommsMain.cs:27)