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IAsyncObserver<T> Interface

  • Reference

Definition

Namespace:
Orleans.Streams
Assembly:
Orleans.dll
Assembly:
Orleans.Core.Abstractions.dll
Assembly:
Orleans.Streaming.dll
Package:
Microsoft.Orleans.Core v1.5.10
Package:
Microsoft.Orleans.Core.Abstractions v2.4.5
Package:
Microsoft.Orleans.Core.Abstractions v3.6.5
Package:
Microsoft.Orleans.Streaming v7.2.5
Package:
Microsoft.Orleans.Streaming v8.0.0

This interface generalizes the standard .NET IObserver interface to allow asynchronous production of items.

Note that this interface is implemented by item consumers and invoked (used) by item producers. This means that the consumer endpoint of a stream implements this interface. 

public interface IAsyncObserver<in T>
type IAsyncObserver<'T> = interface
Public Interface IAsyncObserver(Of In T)

Type Parameters

T

The type of object consumed by the observer.

This type parameter is contravariant. That is, you can use either the type you specified or any type that is less derived. For more information about covariance and contravariance, see Covariance and Contravariance in Generics.
Derived

Methods

OnCompletedAsync()

Notifies the consumer that the stream was completed.

The Task returned from this method should be completed when the consumer is done processing the stream closure.

OnErrorAsync(Exception)

Notifies the consumer that the stream had an error.

The Task returned from this method should be completed when the consumer is done processing the stream closure.

OnNextAsync(T, StreamSequenceToken)

Passes the next item to the consumer.

The Task returned from this method should be completed when the item's processing has been sufficiently processed by the consumer to meet any behavioral guarantees.

When the consumer is the (producer endpoint of) a stream, the Task is completed when the stream implementation has accepted responsibility for the item and is assured of meeting its delivery guarantees. For instance, a stream based on a durable queue would complete the Task when the item has been durably saved. A stream that provides best-effort at most once delivery would return a Task that is already complete.

When the producer is the (consumer endpoint of) a stream, the Task should be completed by the consumer code when it has accepted responsibility for the item. In particular, if the stream provider guarantees at-least-once delivery, then the item should not be considered delivered until the Task returned by the consumer has been completed.

Applies to