XMPP server. How to open TLS connection?

Question

I need help with initialization TLS connection to Firebase Cloud Messaging from my XMPP Java server app. I know that FCM do not support STARTTLS extension. How to do it in the other way?

Answer 1

You are right

Note that FCM doesn't currently support the STARTTLS extension.

https://firebase.google.com/docs/cloud-messaging/auth-server

Also, is described here https://firebase.google.com/docs/cloud-messaging/server#choose , XMPP is a legacy protocol to interact with FCM server

So it's recommended to switch to FCM HTTP v1 API which supports HTTPS