> But don't push notifications basically work over a long lived connection?
It took me a while to understand this, and while other people have answered the question, I want to chime in in hopes it helps other people understand.
Yes, push notifications work over a long-lived connection. The way push notifications in iOS and Android work is that all of your push notifications for all of your apps get sent over one long-lived connection, instead of one per app. Also, (at least on Android), the notifications can be held and batched, so that the device doesn't have to wake up as often to receive notifications. And finally, push notifications are handled by a system service that can wake up other applications, so that messaging applications can be aggressively hibernated to save power, and still receive notifications.
The downside is that your notifications are all centralized. And while a well-designed app like Signal will only send a "wake-up" packet over the push notifications channel, it's still a worrying dependency for some people.
It took me a while to understand this, and while other people have answered the question, I want to chime in in hopes it helps other people understand.
Yes, push notifications work over a long-lived connection. The way push notifications in iOS and Android work is that all of your push notifications for all of your apps get sent over one long-lived connection, instead of one per app. Also, (at least on Android), the notifications can be held and batched, so that the device doesn't have to wake up as often to receive notifications. And finally, push notifications are handled by a system service that can wake up other applications, so that messaging applications can be aggressively hibernated to save power, and still receive notifications.
The downside is that your notifications are all centralized. And while a well-designed app like Signal will only send a "wake-up" packet over the push notifications channel, it's still a worrying dependency for some people.
There's a proposed RFC called webpush that would let you implement/choose your own push to be used by multiple apps: https://datatracker.ietf.org/wg/webpush/documents/