Publish message as a bytes array

[iamaliybi]

How can I publish a message as a bytes array in a specific topic?

[Namoshek]

There are no byte arrays in PHP, but it is the same as a string. So you simply publish the string.

If, for example, you want to publish a binary file, you simply use file_get_contents($file) and publish the result:

$mqtt = new MqttClient($host, $port);
$mqtt->connect();
$mqtt->publish('device/xyz/firmware', file_get_contents($firmwareFile));
$mqtt->disconnect();

[iamaliybi]

This is my message: {"CMD\r\n":"FAST_SCAN\r\n","BROADCAST\r\n":"ALL\r\n"}

When I send it as a string, it doesn't work. Also, I'm using MQTT.js in Frontend side and when I publish a message as Buffer, it's working fine and when I send it as string, it doesn't work.

[Namoshek]

I see no reason why this shouldn't work. Please show the code that is not working for you.

[iamaliybi]

Sure

Javascript: (It's working fine when i send command as Buffer)

const connection= mqtt.connect("ws://IP", {
    port: Number(port),
    clientId: 'mqttjs_' + getRandomName(),
    keepalive: 20,
    clean: true,
    reconnectPeriod: 5E3,
    connectTimeout: 5E3,
});

const command = Buffer.from(`{"CMD\r\n":"FAST_SCAN\r\n","BROADCAST\r\n":"ALL\r\n"}`);

mqtt.publish("Dali/In", command);

Also when I send a command without Buffering, it doesn't work

PHP

$message = '{"CMD\r\n":"FAST_SCAN\r\n","BROADCAST\r\n":"ALL\r\n"}'; // I trying json encode, Doesn't work

$connection = new phpMQTT($server, $port, $randomClientId);
$connection->publish('Dali/In', $message, 0);

[Namoshek]

Besides that the \r\n in the keys and values look totally weird and uncommon to me, this might be an issue with the encoding of \r\n in PHP. There is a difference between single and double quotes in PHP, for reference see this 3v4l.org snippet).

Maybe try this to correctly build the message, if the \r\n really belongs in the message:

$message = json_encode([
    "CMD\r\n" => "FAST_SCAN\r\n",
    "BROADCAST\r\n" => "ALL\r\n"
]);

[iamaliybi]

doesn't work :(

[iamaliybi]

When I sent it as a Buffer in Javascript, i got it in MQTT as:

{'CMD
':'FAST_SCAN
','BROADCAST
':'ALL
'}

Also, I trying to send it

$message = `{"CMD
":"FAST_SCAN
","BROADCAST
":"ALL
"}`;

doesn't work again

[Namoshek]

That doesn't really make sense, since you are sending double quotes also in JS. But anyhow, try this:

$message = "{'CMD\r\n':'FAST_SCAN\r\n','BROADCAST\r\n':'ALL\r\n'}";