在php上检测另一个客户端的http请求

Question

I have a web server (run PHP) and two clients now. both clients are opening the web.

I want that Client A send the HTTP requests (PUT/GET) to the server, for example POST id = 1

then , the server will process the requests ,like do the SQL query search the information of id = 1.

and push the query result (id , other information...) to the Client B immediately .

What technology I should use? or other languages should I use. I hope someone can provide me a simple example.