`StreamSocketListener`-based server in Universal App - xaml

Question

It is known that Windows 8.1 and Windows Phone 8.1 put lots of constraints on background activities of third-party app. For instance, it is impossible to develop server-like capability (e.g. BitTorrent) in Store App without having to keep the screen always-on using DisplayRequest.
From the latest documentation, I have a feeling that one can utilize the method EnableTransferOwnership of StreamSocketListener to delegate the usual request processing code to a background task. The problem is that I don't know how IBackgroundTask should work in this case. Normally, they are activated by some conditions/triggers such as "Internet becomes available". The only sensible trigger in this case seems to be ControlChannelTrigger but apparently, the documentation implies that it cannot be used with StreamSocketListener since the app needs to be the one who creates and register a StreamSocket, not waiting for the socket to be created by some connecting client.
Is it possible now to implement a StreamSocketListener-based server in Windows 10 Universal app platform? If it is, how can I do that?

Answer 1

Use it to activate a background task on socket activity such as receiving data when the app is not active, e.g.:
var socketTaskBuilder = new BackgroundTaskBuilder();
socketTaskBuilder.Name = "SocketActivityBackgroundTask";
socketTaskBuilder.TaskEntryPoint = "SocketActivityBackgroundTask.SocketActivityTask";
var trigger = new SocketActivityTrigger();
socketTaskBuilder.SetTrigger(trigger);
var task = socketTaskBuilder.Register();
socket = new StreamSocket();
socket.EnableTransferOwnership(task.TaskId, SocketActivityConnectedStandbyAction.Wake);
For a complete example, look at the Socket Activity sample or the documentation.