php actively communicates with mobile devices? So how did php find them?
feels the need to make a long connection. The mobile device first requests the server to pull the long connection, and then the server sends it. But php is not naturally suitable for long connections, so you can take a look at wheels such as swoole, or (if possible) replace them with stacks such as Node.js that are suitable for long connections.

this is actually PHP as the server, and App and hardware as the client, which can also be thought of as the data sender
. Then it is divided into two scenarios

• non-instant messaging scenarios

  • for example, just some data is collected from hardware. If users on App take a look at it from time to time, they only need the php server to store the data in the database, and then check it when App calls the API request

• Instant messaging scenarios, such as instant monitoring client data

  • Instant messaging scenarios can use HTTP polling or establishing socket persistent connections. Swoole is a very good choice for socket, especially for later swoole4.x. There is nothing to say about HTTP polling. Request data once every two or three seconds