PHP and MQTT realize real-time presentation and analysis of remote device data

PHP and MQTT realize real-time presentation and analysis of remote device data

Introduction:
With the development of Internet of Things technology, more and more devices are connected to the Internet and generate a large amount of data. In order to obtain and analyze device data in real time, this article will introduce how to use PHP and MQTT protocols to achieve real-time presentation and analysis of remote device data.

1. What is MQTT protocol
MQTT (Message Queuing Telemetry Transport) is a lightweight, flexible and open messaging protocol that is widely used in the field of Internet of Things. The MQTT protocol is based on the publish/subscribe model, supports low-bandwidth, low-power device communication, and has the characteristics of message reliability and high transmission efficiency.

2. Construction of MQTT server

1. Install MQTT server
   Choose to install and configure the MQTT server. This article recommends using Eclipse Mosquitto as the MQTT server. For specific installation methods, please refer to the official documentation. . After successful installation, start the MQTT server.
2. Define MQTT topic
   MQTT topic is used to identify the messages published and subscribed by the device. The theme can be customized according to actual needs, for example: "/devices/device1/temperature".

3. Integration of PHP and MQTT

1. Install the MQTT client library
   Use Composer to install the MQTT client library. You can install it with the following command :

   composer require php-mqtt/client

2. Connect to the MQTT server
   In the PHP file, use the following code to connect to the MQTT server:

   use PhpMqttClientMqttClient;
   
   $mqtt = new MqttClient('mqtt://localhost:1883');
   $mqtt->connect();

   Need to replace 'localhost' with the MQTT server's IP address, '1883' is the default port number of the MQTT server.

3. Publish a message
   Use the following code to publish a message to the specified MQTT topic:

   $topic = '/devices/device1/temperature';
   $payload = '25°C';
   $qosLevel = 0; // 可选，默认为0
   
   $mqtt->publish($topic, $payload, $qosLevel);

   The values ​​of $topic and $payload can be modified according to actual needs.

4. Subscribe to messages
   Use the following code to subscribe to the specified MQTT topic:

   $topic = '/devices/device1/temperature';
   $qosLevel = 0; // 可选，默认为0
   
   $mqtt->subscribe($topic, function ($topic, $message) {
    // 在此处处理接收到的消息
   }, $qosLevel);

   You can process the received message in the callback function, such as storing the message in the database or presented to the front-end interface in real time.

4. Real-time presentation and analysis of device data

1. Use HTML and JavaScript to create a front-end page
   Create an HTML page for real-time presentation of device data . You can use JavaScript to interact with back-end PHP scripts, such as using Ajax technology to regularly obtain device data from the server and refresh the page dynamically.
2. PHP script to get device data
   Create a PHP script to get device data from the database or MQTT server. You can choose to obtain the latest data or data within a specified time range based on your needs.
3. Update device data in real time
   Use JavaScript and Ajax technology to regularly request PHP scripts in the front-end page to obtain device data, and update the data to the page in real time.

5. Summary
This article introduces how to use PHP and MQTT protocols to achieve real-time presentation and analysis of remote device data. Through the publish/subscribe mode of the MQTT protocol, real-time transmission and reliability guarantee of device data can be achieved, and with the help of the powerful functions of PHP, the flexibility of data acquisition, storage and application can be achieved. I hope this article can provide you with some reference and help in the development of Internet of Things applications.

Reference:

1. Eclipse Mosquitto official documentation: https://mosquitto.org/documentation/
2. php-mqtt/client GitHub page: https:/ /github.com/php-mqtt/client

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