akka.stream.javadsl

Class BroadcastHub

java.lang.Object

akka.stream.javadsl.BroadcastHub

public class BroadcastHub
extends java.lang.Object

A BroadcastHub is a special streaming hub that is able to broadcast streamed elements to a dynamic set of consumers. It consissts of two parts, a Sink and a Source. The Sink broadcasts elements from a producer to the actually live consumers it has. Once the producer has been materialized, the Sink it feeds into returns a materialized value which is the corresponding Source. This Source can be materialized arbitrary many times, where weach of the new materializations will receive their elements from the original Sink.

Constructor Summary

Constructors

Constructor and Description
BroadcastHub()

Method Summary

Modifier and Type	Method and Description
static <T> Sink<T,Source<T,NotUsed>>	of(java.lang.Class<T> clazz)
static <T> Sink<T,Source<T,NotUsed>>	of(java.lang.Class<T> clazz, int bufferSize) Creates a Sink that receives elements from its upstream producer and broadcasts them to a dynamic set of consumers.

Methods inherited from class java.lang.Object

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

Constructor Detail

BroadcastHub

public BroadcastHub()

Method Detail

of

public static <T> Sink<T,Source<T,NotUsed>> of(java.lang.Class<T> clazz,
                                               int bufferSize)

Creates a Sink that receives elements from its upstream producer and broadcasts them to a dynamic set of consumers. After the Sink returned by this method is materialized, it returns a Source as materialized value. This Source can be materialized arbitrary many times and each materialization will receive the broadcast elements form the ofiginal Sink.

Every new materialization of the Sink results in a new, independent hub, which materializes to its own Source for consuming the Sink of that materialization.

If the original Sink is failed, then the failure is immediately propagated to all of its materialized Sources (possibly jumping over already buffered elements). If the original Sink is completed, then all corresponding Sources are completed. Both failure and normal completion is "remembered" and later materializations of the Source will see the same (failure or completion) state. Sources that are cancelled are simply removed from the dynamic set of consumers.

Parameters:

clazz - Type of elements this hub emits and consumes

bufferSize - Buffer size used by the producer. Gives an upper bound on how "far" from each other two concurrent consumers can be in terms of element. If the buffer is full, the producer is backpressured. Must be a power of two and less than 4096.

Returns:

(undocumented)

of

public static <T> Sink<T,Source<T,NotUsed>> of(java.lang.Class<T> clazz)