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Check Upload and Download Progress - .NET SDK

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  • Monitor Sync Progress and Status
  • Wait for Changes to be Uploaded or Downloaded
  • Monitor Sync Progress
  • Get Connection State Changes

You may want to know the status of Sync operations in your app. For example, you might want specific code to run only after all of the data is synced with App Services. You might also want to provide users with the status of Sync operations.

You can set up your Sync session to wait for changes to be uploaded or downloaded. You can also configure your Sync session to notify when the Sync connection status changes.

To asynchronously wait for your changes to be completed, get the sync session from the Realms.Sync.SyncSession property, and then call the session.WaitForUploadAsync() or session.WaitForDownloadAsync() methods. For example:

using Realms.Sync;
var realm = Realm.GetInstance(config);
await realm.SyncSession.WaitForDownloadAsync();


Flexible Sync progress notifications are not yet fully supported. When using Flexible Sync, downloads only report notifications after changes are integrated. Partition-Based Sync provides ongoing notifications as changes progress downloading. Uploads report ongoing progress notifications for both Sync Modes.

To monitor Sync progress, get the sync session from the Realms.Sync.SyncSession property, then add a progress notification by calling the session.GetProgressObservable() method.

The session.GetProgressObservable method takes in the following two parameters:

  • A ProgressDirection parameter that can be set to Upload or Download.

  • A ProgressMode parameter that can be set to ReportIndefinitely for the notifications to continue until the callback is unregistered, or ForCurrentlyOutstandingWork for the notifications to continue until only the currently transferable bytes are synced.

When you Subscribe to the notifications, you receive a SyncProgress object that provides the total number of transferrable bytes and the remaining bytes to be transferred.


The number of transferred and transferable bytes are only estimates. The Sync changesets are compressed with gzip before transmitting, so the actual size of transmitted bytes will be smaller than the reported number of both transferable and transferred bytes.


In the following example, we subscribe to a progress observable on the session to listen for upload events indefinitely. When this callback is triggered, it prints the number of transferred bytes and the number of transferable bytes to the console.

var session = realm.SyncSession;
var token = session.GetProgressObservable(ProgressDirection.Upload,
.Subscribe(progress =>
Console.WriteLine($@"transferred bytes:
Console.WriteLine($@"transferable bytes:

Once you no longer wish to receive notifications, unregister the token by using token.Dispose()


The SDK optimizes download speeds by combining multiple changesets into a single download message, up to 16 MB. Since the progress callback is only invoked once before and after a download message is processed, this means that you'll likely see transferredBytes change in increments of roughly 16 MB rather than continuously as the message is being downloaded.

To get the connection state of a SyncSession, set an event handler on the PropertyChanged event. The event handler is a standard .NET PropertyChangedEventHandler delegate that takes in a sender object and PropertyChangedEventArgs object. In the event handler, cast the sender to a Session object and check if the event argument's PropertyName property is Session.ConnectionState. You can then get the ConnectionState value, which will be one of the following:

  • Connecting

  • Connected

  • Disconnected

The following code demonstrates setting the event handler, casting the session object, and checking the Sync status:

public void SetupRealm()
var appConfig = new AppConfiguration(myRealmAppId);
app = App.Create(appConfig);
user = app.LogInAsync(Credentials.Anonymous()).Result;
config = new PartitionSyncConfiguration("myPartition", user);
var realm = Realm.GetInstance(config);
var session = realm.SyncSession;
session.PropertyChanged += SyncSessionPropertyChanged!;
catch (Exception ex)
private void SyncSessionPropertyChanged(object sender, PropertyChangedEventArgs e)
if (e.PropertyName == nameof(Session.ConnectionState))
var session = (Session)sender;
var currentState = session.ConnectionState;
if (currentState == ConnectionState.Connecting)
//session is connecting
if (currentState == ConnectionState.Connected)
//session is connected
if (currentState == ConnectionState.Disconnected)
//session has been disconnected
←  Suspend or Resume a Sync Session - .NET SDKConvert Between Non-Synced Realms and Synced Realms - .NET SDK →
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