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package javax.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 was thrown by a given SSE event output when trying
* 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 the SSE event output has been 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.
*
* 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();
}