# IStreamSubscriptionObserver

Package: [Microsoft.Orleans.Streaming](/orleans/docs/api/csharp/microsoft.orleans.streaming/) 10.0.0

[NuGet package](https://www.nuget.org/packages/Microsoft.Orleans.Streaming) | [Source](https://github.com/dotnet/orleans/blob/e4e752cedecc2976811db49802c7a999b1f1c704/src/Orleans.Streaming/Core/IStreamSubscriptionObserver.cs#L8)

```csharp
public interface IStreamSubscriptionObserver
```

When implemented by a grain, notifies the grain of any new or resuming subscriptions.

## Methods

- [OnSubscribed(IStreamSubscriptionHandleFactory)](/orleans/docs/api/csharp/microsoft.orleans.streaming/orleans.streams.core.istreamsubscriptionobserver/methods/onsubscribed-orleans-streams-core-istreamsubscriptionhandlefactory-81ff0baf/)