WinRT Background Task with Time Trigger Error RRS feed

  • Question

  • I have defined my Background Task as follows:

    public sealed class BackgroundSynchronization:IBackgroundTask
            public async void Run(IBackgroundTaskInstance taskInstance)
                BackgroundTaskDeferral _deferral = taskInstance.GetDeferral();
                //Network Calls
                //Updating Local DB (SQLite)
                myRepository.Save(entity);   // Saves entity in SQLite Table, and Entity has a  Current DateTime field too.

    And Task Register class as

    public static class BackgroundTaskRegister {
        public static  BackgroundTaskRegistration RegisterBackgroundTask(string taskEntryPoint,string taskName,IBackgroundTrigger trigger,IBackgroundCondition condition)
            foreach (var cur in BackgroundTaskRegistration.AllTasks)
                if (cur.Value.Name == taskName)
                    return (BackgroundTaskRegistration)(cur.Value);
            var builder = new BackgroundTaskBuilder();
            builder.Name = taskName;
            builder.TaskEntryPoint = taskEntryPoint;
            if (condition != null)
            BackgroundTaskRegistration task = builder.Register();
            return task;

    And I have registered the triiger in my app as

        TimeTrigger myTrigger = new TimeTrigger(15, false);
        await BackgroundExecutionManager.RequestAccessAsync();
        string entryPoint = "BackgroundTask.BackgroundSynchronization";
        string taskName = "Example per 15 minute background task";
        BackgroundTaskRegistration tsk = BackgroundTaskRegister.RegisterBackgroundTask(entryPoint, taskName, myTrigger, null);
        tsk.Completed += new BackgroundTaskCompletedEventHandler(OnCompleted);

    I also have OnComplete method in my App

     private async void OnCompleted(IBackgroundTaskRegistration task, BackgroundTaskCompletedEventArgs args)
                var settings = ApplicationData.Current.LocalSettings;
                var message = settings.Values["backgroundSyncStatus"].ToString();
                var folder = ApplicationData.Current.LocalFolder;
                StorageFile file;
                var x = await File.DoesFileExistInLocalAsync("BackgroundTaskSucceedLog.txt");
                if (!x)
                    file = await folder.CreateFileAsync("BackgroundTaskSucceedLog.txt");
                   file = await ApplicationData.Current.LocalFolder.GetFileAsync("BackgroundTaskSucceedLog.txt");
                await Windows.Storage.FileIO.AppendTextAsync(file, message.ToString() + " " + DateTime.Now.ToString() + Environment.NewLine);

    The background tasks triggers successfully, & the data is saved to SQLite DB myRepository.Save(entity); table only for the first run. I came to this conclusion as I had logged the entries in OnComplete method.

    The logger results confused me more

    Logger results

    2/16/2015 10:51:41 PM     <--Data Saved in SQLite for this entry
    2/16/2015 11:07:03 PM
    2/16/2015 11:22:26 PM
    2/16/2015 11:37:39 PM
    2/16/2015 11:52:51 PM
    2/17/2015 5:33:00 AM       <--Data Saved in SQLite for this entry

    The data in SQLite is saved only for the first Background Task "for a day". I tried to Debug Background Task., For first run, Everything runs smoothly, & for subsequent run, the compiler after reaching myRepository.Save(entity);, jumps directly to OnComplete method. WHY.???

    Tuesday, February 17, 2015 12:35 PM


  • Hi Gk_999,

    You have a method myRepository.Save(entity); I would like to know if you have too much data need to save into the database, as I know there might be some limitation on background task Supporting your app with background tasks.

    However I would like to get a sample from you instead of the code snippet, it could be quite difficult to debug.


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    Wednesday, February 18, 2015 2:40 AM