N12Heartbeats and keepalives

The problem

1 s on screen = 100 ms

How do you tell a server that died from one with nothing to say?

Open, quiet, and maybe dead

Forty users keep a connection open to one of two push servers. A news desk sends four items a second to both.

Live metrics for each version of the scene
Silent	Heartbeats	Change
—	—	—
—	—	—
0	0	—

N12Heartbeats and keepalives

A dead connection looks exactly like a quiet one. A heartbeat turns silence into a signal.