io.grpc.stub

Interface StreamObserver<V>

public interface StreamObserver<V>

Receives notifications from an observable stream of messages.

It is used by both the client stubs and service implementations for sending or receiving stream messages. For outgoing messages, a StreamObserver is provided by the GRPC library to the application. For incoming messages, the application implements the StreamObserver and passes it to the GRPC library for receiving.

Implementations are expected to be thread-compatible. Separate StreamObservers do not need to be sychronized together; incoming and outgoing directions are independent.

Method Summary

Modifier and Type	Method and Description
void	onCompleted() Receives a notification of successful stream completion.
void	onError(Throwable t) Receives a terminating error from the stream.
void	onNext(V value) Receives a value from the stream.

Method Detail

onNext

void onNext(V value)

Receives a value from the stream.

Can be called many times but is never called after onError(Throwable) or onCompleted() are called.

If an exception is thrown by an implementation the caller is expected to terminate the stream by calling onError(Throwable) with the caught exception prior to propagating it.

Parameters:

value - the value passed to the stream

onError

void onError(Throwable t)

Receives a terminating error from the stream.

May only be called once and if called it must be the last method called. In particular if an exception is thrown by an implementation of onError no further calls to any method are allowed.

Parameters:

t - the error occurred on the stream

onCompleted

void onCompleted()

Receives a notification of successful stream completion.

May only be called once and if called it must be the last method called. In particular if an exception is thrown by an implementation of onCompleted no further calls to any method are allowed.