sending just one time on MQTT server using javascript application

Question

i have an application that connected to a topic on MQTT broker server, i connect using my javascript code that works over web socket port. my problem that when i put my application on webserver, i keep connect and send messages all time .. never stop that . how can solve my code to connect just once and never connect again unless i got disconnected. here is my code.

client = new Paho.MQTT.Client("m23.cloudmqtt.com", 38788,"clientId-O8R8jUxaRM");
client.onConnectionLost = onConnectionLost;
client.onMessageArrived = onMessageArrived;
var options = {
  useSSL: true,
  userName: "peelmimp",
  password: "iold2UAoIs8T",
  onSuccess:onConnect,
  onFailure:doFail
}
client.connect(options);
// called when the client connects
function onConnect() {
  // Once a connection has been made, make a subscription and send a message.
  console.log("onConnect");
  client.subscribe("sensor8");
  message = new Paho.MQTT.Message(" CloudMQTT");
  message.destinationName = "sensor8";
  client.send(message);
}

function doFail(e){
  console.log(e);
}

// called when the client loses its connection
function onConnectionLost(responseObject) {
  if (responseObject.errorCode !== 0) {
    console.log("onConnectionLost:"+responseObject.errorMessage);
    client.connect(options);
  }
}

// called when a message arrives
function onMessageArrived(message) {
  console.log("onMessageArrived:"+message.payloadString);
  var x = message.payloadString;
  if(x == 1){ //park spot number 1
    document.getElementById("park1").style.backgroundColor = "orange";
    document.getElementById("park1p").style.fontSize="40px";
    document.getElementById("park1p").innerHTML="A car is going to park at spot number 1";
  }
  if(x == 2){ //car parked at park1
    document.getElementById("park1").style.backgroundColor = "red";
    document.getElementById("park1p").innerHTML="spot number 1 is not available";
  }
  if(x == 3){ //car left park 1 and it is available
    document.getElementById("park1").style.backgroundColor = "green";
    document.getElementById("park1p").innerHTML="spot number 1 is available";
  }
  if(x == 4){ //park spot number 2
    document.getElementById("park2").style.backgroundColor = "orange";
    document.getElementById("park2p").style.fontSize="40px";
    document.getElementById("park2p").innerHTML="A car is going to park at spot number 2";
  }
  if(x == 5){ //car parked at park2
    document.getElementById("park2").style.backgroundColor = "red";
    document.getElementById("park2p").innerHTML="spot number 2 is not available";
  }
  if(x == 6){ //car left park 2 and it is available
    document.getElementById("park2").style.backgroundColor = "green";
    document.getElementById("park2p").innerHTML="spot number 2 is available";
  }
  if(x == 7){ //park spot number 3
    document.getElementById("park3").style.backgroundColor = "orange";
    document.getElementById("park3p").style.fontSize="40px";
    document.getElementById("park3p").innerHTML="A car is going to park at spot number 3";
  }
  if(x == 8){ //car parked at park3
    document.getElementById("park3").style.backgroundColor = "red";
    document.getElementById("park3p").innerHTML="spot number 3 is not available";
  }
  if(x == 9){ //car left park 3 and it is available
    document.getElementById("park3").style.backgroundColor = "green";
    document.getElementById("park3p").innerHTML="spot number 3 is available";
  }
  if(x == 10){ //park spot number 4
    document.getElementById("park4").style.backgroundColor = "orange";
    document.getElementById("park4p").style.fontSize="40px";
    document.getElementById("park4p").innerHTML="A car is going to park at spot number 4";
  }
  if(x == 11){ //car parked at park4
    document.getElementById("park4").style.backgroundColor = "red";
    document.getElementById("park4p").innerHTML="spot number 4 is not available";
  }
  if(x == 12){ //car left park 4 and it is available
    document.getElementById("park4").style.backgroundColor = "green";
    document.getElementById("park4p").innerHTML="spot number 4 is available";
  }

}

I am assuming those credentials are okay to be displayed? May want to edit out if not! — William Fleming, Mar 04 '18 at 19:34
those credentials for just example . not critical information — DrJempo, Mar 04 '18 at 19:57

score 0 · Accepted Answer · answered Mar 05 '18 at 06:42

You have a single fixed client id and the code automatically reconnects when disconnected.

In your on('connected') callback you publish a message.

Since the broker will only allow a single client to be connected with any given client id it will always kick the oldest one off when a new one connects. This will trigger a reconnection loop as soon as more than one browser opens the page. Hence triggering the message published on connection to be published multiple times.

sending just one time on MQTT server using javascript application

1 Answers1