Automatic mode

System modes

The automatic mode (threading disabled) of connectivity (with threading disabled) provides the default behavior of the device, which is that:

SYSTEM_MODE(AUTOMATIC);

void setup() {
  // This won't be called until the device is connected to the cloud
}

void loop() {
  // Neither will this
}

When the device starts up, it automatically tries to connect to Wi-Fi or Cellular and the Particle Device Cloud.
Once a connection with the Particle Device Cloud has been established, the user code starts running.
Messages to and from the Cloud are handled in between runs of the user loop; the user loop automatically alternates with Particle.process().
Particle.process() is also called during any delay() of at least 1 second.
If the user loop blocks for more than about 20 seconds, the connection to the Cloud will be lost. To prevent this from happening, the user can call Particle.process() manually.
If the connection to the Cloud is ever lost, the device will automatically attempt to reconnect. This re-connection will block from a few milliseconds up to 8 seconds.
SYSTEM_MODE(AUTOMATIC) does not need to be called, because it is the default state; however the user can invoke this method to make the mode explicit.