I'm not sure I am reading the docs correctly but in the Firebase Cloud Messaging documentation discussing Firebase Cloud Messaging Server they mention the tradeoffs of using HTTP vs XMPP and I read the following in HTTP:
HTTP: Synchronous. App servers send messages as HTTP POST requests and wait for a response. This mechanism is synchronous and blocks the sender from sending another message until the response is received.
Does this mean if I have multiple unrelated pushes that need to be sent to various devices, that I cannot send a second request until the first request is received? If I have three workers handling push notifications they would need to keep track of whether or not another one is waiting for a response from Firebase or am I misunderstanding the point?