io.grpc.stub

Class ServerCallStreamObserver<V>

java.lang.Object

io.grpc.stub.CallStreamObserver<V>

io.grpc.stub.ServerCallStreamObserver<V>

All Implemented Interfaces:

StreamObserver<V>

@ExperimentalApi(value="https://github.com/grpc/grpc-java/issues/1788")
public abstract class ServerCallStreamObserver<V>
extends CallStreamObserver<V>

A refinement of CallStreamObserver to allows for interaction with call cancellation events on the server side.

Like StreamObserver, implementations are not required to be thread-safe; if multiple threads will be writing to an instance concurrently, the application must synchronize its calls.

DO NOT MOCK: The API is too complex to reliably mock. Use InProcessChannelBuilder to create "real" RPCs suitable for testing and interact with the server using a normal client stub.

Constructor Summary

Constructors

Constructor and Description
ServerCallStreamObserver()

Method Summary

Modifier and Type	Method and Description
void	disableAutoRequest() Swaps to manual flow control where no message will be delivered to StreamObserver.onNext(Object) unless it is request()ed.
abstract boolean	isCancelled() If true indicates that the call has been cancelled by the remote peer.
abstract void	setCompression(String compression) Sets the compression algorithm to use for the call.
abstract void	setOnCancelHandler(Runnable onCancelHandler) Set a Runnable that will be called if the calls isCancelled() state changes from false to true.

Methods inherited from class io.grpc.stub.CallStreamObserver

disableAutoInboundFlowControl, isReady, request, setMessageCompression, setOnReadyHandler

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.grpc.stub.StreamObserver

onCompleted, onError, onNext

Constructor Detail

ServerCallStreamObserver

public ServerCallStreamObserver()

Method Detail

isCancelled

public abstract boolean isCancelled()

If true indicates that the call has been cancelled by the remote peer.

This method may safely be called concurrently from multiple threads.

setOnCancelHandler

public abstract void setOnCancelHandler(Runnable onCancelHandler)

Set a Runnable that will be called if the calls isCancelled() state changes from false to true. It is guaranteed that execution of the Runnable are serialized with calls to the 'inbound' StreamObserver.

Note that the handler may be called some time after isCancelled() has transitioned to true as other callbacks may still be executing in the 'inbound' observer.

Setting the onCancelHandler will suppress the on-cancel exception thrown by StreamObserver.onNext(V).

Parameters:

onCancelHandler - to call when client has cancelled the call.

setCompression

public abstract void setCompression(String compression)

Sets the compression algorithm to use for the call. May only be called before sending any messages. Default gRPC servers support the "gzip" compressor.

It is safe to call this even if the client does not support the compression format chosen. The implementation will handle negotiation with the client and may fall back to no compression.

Parameters:

compression - the compression algorithm to use.

Throws:

IllegalArgumentException - if the compressor name can not be found.

disableAutoRequest

public void disableAutoRequest()

Swaps to manual flow control where no message will be delivered to StreamObserver.onNext(Object) unless it is request()ed.

It may only be called during the initial call to the application, before the service returns its StreamObserver.

Note that for cases where the message is received before the service handler is invoked, this method will have no effect. This is true for:

• MethodDescriptor.MethodType.UNARY operations.
• MethodDescriptor.MethodType.SERVER_STREAMING operations.

This API is still a work in-progress and may change in the future.