io.grpc.stub.StreamObserver Maven / Gradle / Ivy
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package io.grpc.stub;
/**
* 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 {@code StreamObserver} is provided by the GRPC library
* to the application. For incoming messages, the application implements the {@code StreamObserver}
* and passes it to the GRPC library for receiving.
*
*
Implementations are expected to be thread-compatible. Separate {@code StreamObserver}s do
* not need to be sychronized together; incoming and outgoing directions are independent.
*/
public interface StreamObserver {
/**
* Receives a value from the stream.
*
* Can be called many times but is never called after {@link #onError(Throwable)} or {@link
* #onCompleted()} are called.
*
*
If an exception is thrown by an implementation the caller is expected to terminate the
* stream by calling {@link #onError(Throwable)} with the caught exception prior to
* propagating it.
*
* @param value the value passed to the stream
*/
public void onValue(V value);
/**
* Receives a terminating error from the stream.
*
*
May only be called once and is never called after {@link #onCompleted()}. In particular if
* an exception is thrown by an implementation of {@code onError} no further calls to any
* method are allowed.
*
* @param t the error occurred on the stream
*/
public void onError(Throwable t);
/**
* Receives a notification of successful stream completion.
*
*
May only be called once and is never called after {@link #onError(Throwable)}. In particular
* if an exception is thrown by an implementation of {@code onCompleted} no further calls to
* any method are allowed.
*/
public void onCompleted();
}