Remove Messaging direct channel and Upstream API at next major change release

[charlotteliang]

Firebase Messaging direct channel and upstream API have been deprecated and will be removed at the Firebase 7 major release.

[thatfiredev]

Hi @chliangGoogle
I'm curious: Why did upstream message get removed from the iOS SDK, but is still available on Android?

[charlotteliang]

Because upstream message uses direct channel. It is available in Android because it's the default channel. Now Firebase Messaging iOS only uses APNS channel for message delivery.

[thatfiredev]

@chliangGoogle Ah, I see.. Thanks for clarifying.