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# MQTT adapter
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MQTT adapter provides an MQTT API for sending and receiving messages through the
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platform.
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## Configuration
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The service is configured using the environment variables presented in the
following table. Note that any unset variables will be replaced with their
default values.
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| Variable | Description | Default |
|-----------------------------|-------------------------------------------------------|-----------------------|
| MF_MQTT_ADAPTER_LOG_LEVEL | MQTT adapter log level | error |
| MF_MQTT_ADAPTER_PORT | Service MQTT port | 1883 |
| MF_MQTT_ADAPTER_WS_PORT | WebSocket port | 8880 |
| MF_NATS_URL | NATS instance URL | nats://localhost:4222 |
| MF_MQTT_ADAPTER_REDIS_PORT | Redis port | 6379 |
| MF_MQTT_ADAPTER_REDIS_HOST | Redis host | localhost |
| MF_MQTT_ADAPTER_REDIS_PASS | Redis pass | mqtt |
| MF_MQTT_ADAPTER_REDIS_DB | Redis db | 0 |
| MF_MQTT_CONCURRENT_MESSAGES | Number of messages that can be concurrently exchanged | 100 |
| MF_THINGS_URL | Things service URL | localhost:8181 |
| MF_MQTT_ADAPTER_CLIENT_TLS | Flag that indicates if TLS should be turned on | false |
| MF_MQTT_ADAPTER_CA_CERTS | Path to trusted CAs in PEM format | |
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## Deployment
The service is distributed as Docker container. The following snippet provides
a compose file template that can be used to deploy the service container locally:
```yaml
version: "2"
services:
mqtt:
image: mainflux/mqtt:[version]
container_name: [instance name]
ports:
- [host machine port]:[configured port]
environment:
MF_THINGS_URL: [Things service URL]
MF_NATS_URL: [NATS instance URL]
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MF_MQTT_ADAPTER_LOG_LEVEL: [MQTT adapter log level]
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MF_MQTT_ADAPTER_PORT: [Service MQTT port]
MF_MQTT_WS_PORT: [Service WS port]
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MF_MQTT_REDIS_PORT: [Redis port]
MF_MQTT_REDIS_HOST: [Redis host]
MF_MQTT_REDIS_PASS: [Redis pass]
MF_MQTT_REDIS_DB: [Redis db]
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MF_MQTT_CONCURRENT_MESSAGES: [Number of messages that can be concurrently exchanged]
MF_MQTT_ADAPTER_CLIENT_TLS: [Flag that indicates if TLS should be turned on]
MF_MQTT_ADAPTER_CA_CERTS: [Path to trusted CAs in PEM format]
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```
To start the service outside of the container, execute the following shell script:
```bash
# download the latest version of the service
go get github.com/mainflux/mainflux
cd $GOPATH/src/github.com/mainflux/mainflux/mqtt
# install dependencies
npm install
# set the environment variables and run the service
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MF_THINGS_URL=[Things service URL] MF_NATS_URL=[NATS instance URL] MF_MQTT_ADAPTER_LOG_LEVEL=[MQTT adapter log level] MF_MQTT_ADAPTER_PORT=[Service MQTT port] MF_MQTT_WS_PORT=[Service WS port] MF_MQTT_REDIS_PORT=[Redis port] MF_MQTT_REDIS_HOST=[Redis host] MF_MQTT_REDIS_PASS=[Redis pass] MF_MQTT_REDIS_DB=[Redis db] MF_MQTT_CONCURRENT_MESSAGES=[Number of messages that can be concurrently exchanged] MF_MQTT_ADAPTER_CLIENT_TLS=[Flag that indicates if TLS should be turned on] MF_MQTT_ADAPTER_CA_CERTS=[Path to trusted CAs in PEM format] node mqtt.js ..
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```
## Usage
To use MQTT adapter you should use `channels/<channel_id>/messages` . Client key should
be passed as user's password. If you want to use MQTT over WebSocket, you could use
[Paho client ](https://www.eclipse.org/paho/ ):
```
<!DOCTYPE html>
< html >
< head >
< meta http-equiv = "Content-Type" content = "text/html;charset=utf-8" / >
< script src = "https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.0.2/mqttws31.min.js" type = "text/javascript" > < / script >
< script type = "text/javascript" >
var wsbroker = "localhost"; //mqtt websocket enabled broker
var wsport = 443 // port for above
var client = new Paho.MQTT.Client(wsbroker, Number(wsport), '');
client.onConnectionLost = function (responseObject) {
console.log("connection lost: " + responseObject.errorMessage);
};
client.onMessageArrived = function (message) {
console.log("Msg", message.destinationName, ' -- ', message.payloadString);
};
var options = {
timeout: 3,
userName: "< thing_id > ", // Replace < :your_thing_id >
password: "< thing_key > ", // Replace < :your_thing_key >
useSSL: true,
onSuccess: function () {
console.log("mqtt connected");
// Connection succeeded; subscribe to our topic, you can add multile lines of these
client.subscribe('channels/< channel_id > /messages', {qos: 1}); // Replace < :your_channel_id >
// use the below if you want to publish to a topic on connect
var payload = [
{
"bn":"e35b157f-21b8-4adb-ab59-9df21461c815",
"bt":1.276020076001e+09,
"bu":"A",
"bver":5,
"n":"voltage",
"u":"V",
"v":120.1
},
{
"n":"current",
"t":-5,
"v":1.2
},
{
"n":"current",
"t":-4,
"v":1.3
}
];
var message = new Paho.MQTT.Message(JSON.stringify(payload));
message.destinationName = "channels/< channel_id > /messages"; // Replace < :your_channel_id >
client.send(message);
},
onFailure: function (message) {
console.log("Connection failed: " + message.errorMessage);
}
};
function init() {
client.connect(options);
}
< / script >
< / head >
< body onload = "init();" >
< / body >
< / html >
```
