There are two possible “success” responses that may be returned from the initial call you make to appear on the lock screen. Both responses are related to real-time connectivity (RTC), and notify the app whether connectivity is allowed in low power mode. Although the triggers already covered should suffice for most apps, some applications may require a more persistent channel for communication. An example is an email app that must load message headers and even retrieve full message bodies for the user when the device is in standby mode so they are readily available when powered on. Fortunately, Windows 8.1 enables this capability with the ControlChannelTrigger.
The ControlChannelTrigger enables real-time network status and triggers for communication using a MessageWebSocket, a StreamWebSocket, or a StreamSocket. The network trigger is designed to minimize network and system resource usage. The device can drop into a low-power mode for periods of time while maintaining the network connection. The app can supply an interval for the system to wake the app up, and can also set a trigger to wake the app when network data is received.