How to respond to an external request in wordpress?

Question

WordPress

It is necessary to implement a response from wordpress to a request from another site. At first I just put a file in the root with vp and tried to make a request, everything worked out, but as soon as I connect this file to vp using

require($_SERVER['DOCUMENT_ROOT'] . '/wp-load.php');

then the answer is no more.
Then it was done like this, in custom-functions.php connected as the plugin wrote

add_action( 'wp_ajax_myactionname, 'myaction_ajax');
add_action( 'wp_ajax_nopriv_myactionname', 'myaction_ajax');
function myaction_ajax(){
  print "OK";
}

, on another site, the call goes to mysite.ru/wp-admin/admin-ajax.php?action=myactionname, but nothing happens. Tell me how to process the request and respond to it from WP.

Answer 1

I think in your case you need to use the WP REST API