how to join android app with a kodi addon

Realization of an Android-App + Kodi Addon (running on a Linux-Machine) + PHP-Script.
(see attachment)
1- The App sends a message (e.g. “Kodi”) to the Addon.
2- The Addon starts another PHP-Script and forwards the message to it.
3- The PHP-Script responses with “Hello Kodi”.
4- The Android-App shows then the Response from Kodi.