I am planning to build a home automation system where IoT devices communicate with the MQTT broker.The system also involves a Django web server that serves API for ios/android devices. I will describe an example of what I want to implement.
An API call is made from mobile app to Django server to turn ON a device. When such API request is made to Django, it should push 'Turn ON' data to IoT device via MQTT protocol.
Also, IoT devices send some real time data to the MQTT broker. Upon receiving such data I want to send push notifications to a mobile app via apns/fcm.
How can I implement this?. Will Django channels serve the purpose or should I code my Django server to act as an MQTT client and communicate with the MQTT broker?. Or is there any other methods to implement this.
well, i did a little project on paho-MQTT it's a nice experience with google chrome extension MQTTLens.(you should try this if u aren't using this already)
in your case, I think you can use rest-framework of Django for building an API and on the front-end, you can use crispy-form to make ON-OFF signals and this will directly communicate to the views of Django in which you can write the client and subscriber details.
lets focus on An API call is made from mobile app to Django server to turn ON a device. When such API request is made to Django, it should push 'Turn ON' data to IoT device via MQTT protocol.
- you can make views which response to the API call from any devices for that you can check django-rest-framework this is the best option that we have.
and now IoT devices send some real time data to the MQTT broker
- for this, you can check Google's this artical. MQTT broker can be handed with the Django views easily and this process not very complex if you use the modular structure with Django's DRY concpet.
on the other hand, you can also make different views for just client or for broker it's up to you but i think this approach will take a long time to devlope such application I don't know about mobile development so i can't help you with that :(.
You can handle the task using JavaScript. I have experience in implementing MQTT protocol in Django and Django-REST projects using JavaScript. You should embed a JavaScript code block in your frontend file (in my case, HTML). First, you should call the Paho-MQTT jQuery package in your file.
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.0.2/mqttws31.min.js"></script>
Then add this block of code.
#parameters
var hostname = "mqtt.eclipse.org"; #There are different brokers. You should enter the broker's hostname.
var port = 80; #The port number can be different based on a TLS or non-TLS connection.
var ClientID = "ClientID_" + parseInt(Math.random()*100);
#Create a client instance
var client = new Paho.MQTT.Client(hostname, Number(port), ClientID);
#Set callback handlers
client.onConnectionLost = onConnectionLost;
client.onMessageArrived = onMessageArrived;
#Connect the client
client.connect(
{onSuccess: onConnect}
);
#Called when client connects
function onConnect() {
#Once a connection has been established, make a subscription and send a message
console.log("onConnect");
client.subscribe("subTopic");
alert("Connected.");
}
#Called when the client loses its connection
function onConnectionLost(responseObject){
if(responseObject.errorCode != 0){
console.log("onConnectionLost:" + responseObject.errorMessage);
}
}
#Called when a message arrives
function onMessageArrived(message) {
console.log("Message arrived: topic=" + message.destinationName + ", message=" + message.payloadString);
if (message.destinationName == "subTopic") {
#Do something
}
By using the code your application will be connected to the broker and listen to one or multiple topics. It means you can get sensors' data realtime. This necessitates to publish sensor's data on your hardware device, say ESP module or Raspberry PI.
It is very likely that you want to send commands from your application to the actuators to turn them on or off. For doing that you need to publish some messages from your application that your hardware will listen to.
Assume you have a toggle switch that you want to publish a message by toggling that.
<label id="switch{{ device.unique_id }}" class="switch">
<input id="state{{ device.unique_id }}" type="checkbox" onclick="publish('{{ device.unique_id }}')">
<span class="slider round"></span>
</label>
The above HTML block should reside into a django for block. Then you should write the publish onclick function to call that on toggling the switch. You can see an example of such a function below.
function publish(x) {
if(!client){
return;
}
var status = document.getElementById(x);
if (status.innerHTML == 'ON'){
status.innerHTML = 'OFF';
var message = new Paho.MQTT.Message("TurnOFF");
message.destinationName = "pubTopic";
client.send(message);
} else {
status.innerHTML = 'ON';
var message = new Paho.MQTT.Message("TurnON");
message.destinationName = "pubTopic";
client.send(message);
}
}
x in the publish function is the id that is embedded in the HTML file. To receive your published messages you should listen to the specific topic(s) on your hardware device.
