Rosbridge: received a message without an op
I'm starting my web page from my laptop. The Web page is on my raspberry PI 4. I'm starting rosbridge_server from my raspberry PI too. I'm using ROS Noetic and Ubuntu 20.04. I'm trying to access raspberry PI from my laptop using my web page where I try to establish ssh connection.
I've received the following error:
Received a message without an op. All messages require 'op' field with value one of: ['call_service', 'advertise', 'unadvertise', 'publish', 'subscribe', 'unsubscribe', etc...]
How to resolve this issue?
Below is my html code:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<script type="text/javascript" src="http://static.robotwebtools.org/roslibjs/current/roslib.min.js"></script>
<script type="text/javascript" type="text/javascript">
var ros = new ROSLIB.Ros({
url: "ws://192.168.100.34:8080",
});
var mainSocket = new WebSocket("ws://192.168.100.34:8080");
mainSocket.onopen = function (event) {
mainSocket.sent(JSON.stringify({ action: "connect", host: "ubiquityrobot", port: 22, username: "ubuntu", password: "ubuntu" }));
document.getElementById("conn").innerHTML = "Socket open success";
};
ros.on("connection", function () {
document.getElementById("status").innerHTML = "Connected";
});
ros.on("error", function (error) {
document.getElementById("status").innerHTML = "Error";
});
ros.on("close", function () {
document.getElementById("status").innerHTML = "Closed";
});
</script>
</head>
<body>
<h1>Simple ROS User Interface</h1>
<p>Connection status: <span id="status"></span></p>
<p id="conn"></p>
</body>
</html>
Your code is not here, please edit your question + the more info about your setup, the better
First, you are connecting to
rosbridge_serveratws://192.168.100.34:8080, and then you are creating a web socket at the same URI. Later you seem to send data to that socket. This is probably the cause of the error. You should not touch the URI forrosbridge_serveragain. Furthermore, the default port forrosbridge_serveris 9090. If I remember correctly, port 8080 was used by tomcat in the past. I would not pick this port number forrosbridge_server.Thank you for reply. Could you please help me to modify my code without touching the URI again? Thank you in advance!
I am having a hard time understanding the above line.
Just remove
var mainSocket = new WebSocket( ... )and get rid ofmainSocket.onopen = ...below.Thank you for your reply! I think that if I remove
I can't establish a connection with my raspberry PI. Normally I open the shell of Ubuntu and write
ssh ubuntu@ubiquityrobot.local. Then I have to write the password and finally I can access my raspberry PI. I would like to make the same procedure with my webpage but without using the shell. Therefore I think that I need this functionmainSocket.onopen = ...I understand.
sshaccess to the Raspberry PI using aWebSocket? Please think about it!rosbridge_serverandsshruns on 9090 and 22 port, respectively. Please check and correct those port numbers.sshconnection using aWebSocket. I do not understand why someone would pick aWebSocketto connect to ssh. Please read a similar question asked in StackOverflow for further details.These comments can be helpful for the future readers, please add them as an answer + move the discussion with @tiho_bg here