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/*
* Copyright (c) 2012, 2019 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package jakarta.ws.rs.sse;
import java.util.concurrent.CompletionStage;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
/**
* Server-Sent events broadcasting facility.
*
* Server broadcaster can be used to manage multiple {@link SseEventSink server sinks}. It enables sending events to all
* registered event outputs and provides facility to effectively handle exceptions and closures of individual registered
* event outputs.
*
* Instance of this interface is thread safe, meaning that it can be shared and its method invoked from different
* threads without causing inconsistent internal state.
*
* @author Marek Potociar
* @since 2.1
*/
public interface SseBroadcaster extends AutoCloseable {
/**
* Register a listener, which will be called when an exception is thrown by a given {@link SseEventSink}
* when this SseBroadcaster tries to write to it or close it.
*
* This operation is potentially slow, especially if large number of listeners get registered in the broadcaster. The
* {@code SseBroadcaster} implementation is optimized to efficiently handle small amounts of concurrent listener
* registrations and removals and large amounts of registered listener notifications.
*
* @param onError bi-consumer, taking two parameters: {@link SseEventSink}, which is the source of the error and the
* actual {@link Throwable} instance.
*/
void onError(BiConsumer onError);
/**
* Register a listener, which will be called when this SseBroadcaster closes a given event {@link SseEventSink} or
* tries to write to a given {@link SseEventSink} that is already closed (either by client closing the connection
* or by calling {@link SseEventSink#close()} on the server side.
*
* This operation is potentially slow, especially if large number of listeners get registered in the broadcaster. The
* {@code SseBroadcaster} implementation is optimized to efficiently handle small amounts of concurrent listener
* registrations and removals and large amounts of registered listener notifications.
*
* @param onClose consumer taking single parameter, a {@link SseEventSink}, which was closed.
*/
void onClose(Consumer onClose);
/**
* Register provided {@link SseEventSink} instance to this {@code SseBroadcaster}.
*
* @param sseEventSink to be registered.
*/
void register(SseEventSink sseEventSink);
/**
* Publish an SSE event to all registered {@link SseEventSink} instances.
*
* @param event SSE event to be published.
* @return completion stage that completes when the event has been broadcast to all registered event sinks.
*/
CompletionStage broadcast(final OutboundSseEvent event);
/**
* Close the broadcaster and all registered {@link SseEventSink} instances. Any other resources associated with the
* {@link SseBroadcaster} should be released. This method is equivalent to calling {@code close(true)}.
*
* Subsequent calls have no effect and are ignored. Once the {@link SseBroadcaster} is closed, invoking any other method
* on the broadcaster instance would result in an {@link IllegalStateException} being thrown.
*/
@Override
void close();
/**
* Close the broadcaster and release any resources associated with it. The closing of registered {@link SseEventSink} is
* controlled by the {@code cascading} parameter.
*
* Subsequent calls have no effect and are ignored. Once the {@link SseBroadcaster} is closed, invoking any other method
* on the broadcaster instance would result in an {@link IllegalStateException} being thrown.
*
* @param cascading Boolean value that controls closing of registered {@link SseEventSink} instances.
*/
void close(boolean cascading);
}