Technical guide to remote lighting control using PHP and MQTT

Technical Guide to Implementing Remote Light Control Using PHP and MQTT

Introduction:
With the continuous development of the Internet of Things, remote control devices are becoming more and more common. Remote lighting control is also one of the applications, and this function can be easily achieved using PHP and MQTT. This article will introduce how to use PHP and MQTT to implement remote lighting control, and provide code examples for readers' reference.

1. Preparation

1. Install the MQTT server
   First, you need to install the MQTT server. Commonly used MQTT servers include Mosquitto and RabbitMQ. You can choose the appropriate MQTT server for installation according to your own needs, and ensure that the server can run normally.

2. Create database table
   Create a database table to store light status information. You can use MySQL or other database management systems to create tables. The table structure is as follows:

   CREATE TABLE `lights` (
    `id` INT(11) NOT NULL AUTO_INCREMENT,
    `name` VARCHAR(50) NOT NULL,
    `status` ENUM('off', 'on') NOT NULL DEFAULT 'off',
    PRIMARY KEY (`id`)
   ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

3. Install MQTT client library
   Using MQTT in PHP requires the use of the MQTT client library . The MQTT client library can be installed using the mosquitto package. You can use the following command to install the mosquitto package:

   sudo apt-get install mosquitto
   sudo apt-get install php-mosquitto

   After the installation is complete, you can verify whether the mosquitto extension is installed successfully by running php -m | grep mosquitto.

2. Write PHP code

First, you need to write PHP code to achieve remote lighting control.

1. Connecting to the MQTT server
   First, you need to introduce the MQTT client library and use MosquittoClient to connect to the MQTT server. The code is as follows:

   $client = new MosquittoClient();
   $client->connect('127.0.0.1', 1883, 60);

2. Subscribe to the MQTT topic
   Next, you need to subscribe to the MQTT topic to receive remote control instructions. You can use the onMessage method of MosquittoClient to handle the received message. The code is as follows:

   $client->onMessage(function($message){
     // 处理收到的消息
   });
   
   $client->subscribe('light_control/#', 1);

3. Processing the received message
   In the onMessage callback function, the received message can be processed. In this example, we will update the light status in the database and publish the current status to subscribers. The code is as follows:

   $client->onMessage(function($message) use ($client){
     $payload = $message->payload;
     list($command, $lightId) = explode('/', $message->topic);
   
     // 更新数据库中的灯光状态
     // ...
   
     // 发布当前状态给订阅者
     $client->publish("light_status/$lightId", $payload, 1);
   });

4. Control the light status
   Finally, you need to provide an interface that can control the light status. In this example, we will use GET requests to control the light status. The code looks like this:

   if ($_SERVER['REQUEST_METHOD'] === 'GET' && isset($_GET['lightId']) && isset($_GET['status'])) {
     $lightId = $_GET['lightId'];
     $status = $_GET['status'];
   
     // 更新数据库中的灯光状态
     // ...
   
     // 发布状态给订阅者
     $client->publish("light_status/$lightId", $status, 1);
   }

   The complete PHP code example can be found in the appendix of this article.

3. Summary

This article introduces how to use PHP and MQTT to achieve remote lighting control. First, you need to install the MQTT server and create the corresponding database table. Then, write PHP code to connect to the MQTT server, subscribe to the MQTT topic, process the received messages, and provide an interface to control the light status. Hope this article can be helpful to readers.

Appendix: Complete PHP code example

connect('127.0.0.1', 1883, 60);

$client->onMessage(function($message) use ($client){
  $payload = $message->payload;
  list($command, $lightId) = explode('/', $message->topic);

  // 更新数据库中的灯光状态
  // ...

  // 发布当前状态给订阅者
  $client->publish("light_status/$lightId", $payload, 1);
});

$client->subscribe('light_control/#', 1);

if ($_SERVER['REQUEST_METHOD'] === 'GET' && isset($_GET['lightId']) && isset($_GET['status'])) {
  $lightId = $_GET['lightId'];
  $status = $_GET['status'];

  // 更新数据库中的灯光状态
  // ...

  // 发布状态给订阅者
  $client->publish("light_status/$lightId", $status, 1);
}

while (true) {
  $client->loop();
  sleep(1);
}
?>

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