protected override void OnStart()
{
var target_uri = TargetUri;
if (target_uri==null &&
AppSettingsReader.TryGetUri("PCPPortChecker", out target_uri)) {
TargetUri = target_uri;
}
base.OnStart();
CheckAsync()
.ContinueWith(prev => {
if (prev.IsCanceled || prev.IsFaulted) return;
this.Application.PeerCast.IsFirewalled = !prev.Result.IsOpen;
});
}