How can I send a Firebase Cloud Messaging notification without use the Firebase Console?

I'm starting with the new Google service for the notifications, `Firebase Cloud Messaging`. Thanks to this code https://github.com/firebase/quickstart-android/tree/master/messaging I was able to send notifications from my **Firebase User Console** to my Android device. Is there any API or way to send a notification without use the Firebase console? I mean, for example, a PHP API or something like that, to create notifications from my own server directly.