public LinearAccelerationPageViewModel()
{
// Command to start the subscription
ToggleSubscribeSwitchCommand = new Xamarin.Forms.Command(
async() =>
{
if (IsSubscribeSwitchOn)
{
ConnectionStatusText = "Connecting...";
await MovesenseDeviceVM.Connect();
ConnectionStatusText = "Subscribing...";
subscription = await MovesenseDeviceVM.MovesenseDevice.SubscribeAccelerometerAsync(
(d) =>
{
PlotData(d.Data.Timestamp, d.Data.AccData[0].X, d.Data.AccData[0].Y, d.Data.AccData[0].Z);
},
26);
ConnectionStatusText = "Subscribed";
}
else
{
// Unsubscribe
subscription.Unsubscribe();
ConnectionStatusText = "Unsubscribed";
await MovesenseDeviceVM.Disconnect();
ConnectionStatusText = "Disconnected";
}
}
, () => (MovesenseDeviceVM != null) // Enable command only if we've got a device
);
InitPlotModel();
}
private Task <IMdsSubscription> doSubscribe(Action <T> notificationCallback)
{
mTcs = new TaskCompletionSource <IMdsSubscription>();
mNotificationCallback = notificationCallback;
#if __ANDROID__
var mds = (Com.Movesense.Mds.Mds)CrossMovesense.Current.MdsInstance;
var subscription = mds.Subscribe(
URI_EVENTLISTENER,
FormatContractToJson(Util.GetVisibleSerial(mDeviceName), mPath),
this
);
Subscription = new MdsSubscription(subscription);
#elif __IOS__
var mds = (Movesense.MDSWrapper)CrossMovesense.Current.MdsInstance;
Movesense.MDSResponseBlock responseBlock = new Movesense.MDSResponseBlock((arg0) => OnSubscribeCompleted(arg0));
Movesense.MDSEventBlock eventBlock = (Movesense.MDSEvent arg0) => OnSubscriptionEvent(arg0);
string path = Util.GetVisibleSerial(mDeviceName) + mPath;
mds.DoSubscribe(path, new Foundation.NSDictionary(), responseBlock, eventBlock);
// Save the path to the subscription for the device in the MdsSubscription
Subscription = new MdsSubscription(path);
#endif
return(mTcs.Task);
}
/// <summary>
/// Subscribe to the resource
/// </summary>
/// <param name="notificationCallback">Callback function that will receive periodic notifications with data from the subscription resource</param>
/// <returns>The subscription context</returns>
public async Task <IMdsSubscription> SubscribeWithRetryAsync(Action <T> notificationCallback)
{
TaskCompletionSource <IMdsSubscription> retryTcs = new TaskCompletionSource <IMdsSubscription>();
IMdsSubscription result = null;
bool doRetry = true;
while (doRetry)
{
try
{
result = await doSubscribe(notificationCallback);
retryTcs.SetResult(result);
doRetry = false;
}
catch (Exception ex)
{
bool?mCancelled = RetryFunction?.Invoke(ex);
if (mCancelled.HasValue && mCancelled.Value)
{
// User has cancelled - break out of loop
Debug.WriteLine($"MAX RETRY COUNT EXCEEDED giving up Mds Api Call after exception: {ex.ToString()}");
retryTcs.SetException(ex);
throw ex;
}
else
{
Debug.WriteLine($"RETRYING Mds Api Call after exception: {ex.ToString()}");
await Task.Delay(RETRY_DELAY);
}
}
}
return(result);
}
/// <summary>
/// Unsubscribe from the MdsLib resource
/// </summary>
public void UnSubscribe()
{
Debug.WriteLine("Unsubscribing Mds api subscription");
Subscription?.Unsubscribe();
Subscription = null;
}
