问题
Sending messages from one device directly to another device it not supported through Firebase Cloud Messaging. -- Frank van Pufflenen - JUNE 23 2016
That was quite some time ago, and there aren't any updates in the docs. However:
- Has there been any changes?
- Is Firebase the only option? Are there any other app servers (Like Firebase and the shut-down Parse)?
- I don't want to find/buy a server just for this. But is the Firebase Server SDK suitable for this?
- Can this be implemented using GCM?
回答1:
There have been lots of changes.
But:
Sending a message from one device to another still requires the use of a server key, which means you will need a trusted server.
Recommending services is off-topic here on Stack Overflow.
The Firebase Server SDK is for use on a trusted server.
No, sending device to device messages was only possible with Google Cloud Messaging by using a trusted server.
来源：https://stackoverflow.com/questions/40723864/how-to-send-one-to-one-upstream-messaging-using-not-not-using-fcm-without-hostin