Package org.axonframework.eventhandling

Class AbstractEventBus

java.lang.Object

org.axonframework.eventhandling.AbstractEventBus

All Implemented Interfaces:

EventBus, MessageDispatchInterceptorSupport<EventMessage<?>>, SubscribableMessageSource<EventMessage<?>>

Direct Known Subclasses:

AbstractEventStore, SimpleEventBus

public abstract class AbstractEventBus
extends Object
implements EventBus

Base class for the Event Bus. In case events are published while a Unit of Work is active the Unit of Work root coordinates the timing and order of the publication.

This implementation of the EventBus directly forwards all published events (in the callers' thread) to subscribed event processors.

Since:

3.0

Author:

Allard Buijze, René de Waele

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AbstractEventBus.Builder	Abstract Builder class to instantiate AbstractEventBus implementations.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AbstractEventBus(AbstractEventBus.Builder builder)	Instantiate an AbstractEventBus based on the fields contained in the AbstractEventBus.Builder.

Method Summary

Modifier and Type	Method	Description
protected void	afterCommit(List<? extends EventMessage<?>> events)	Process given events after the Unit of Work has been committed.
protected void	commit(List<? extends EventMessage<?>> events)	Process given events while the Unit of Work root is being committed.
protected List<? extends EventMessage<?>>	intercept(List<? extends EventMessage<?>> events)	Invokes all the dispatch interceptors.
protected void	prepareCommit(List<? extends EventMessage<?>> events)	Process given events while the Unit of Work root is preparing for commit.
void	publish(List<? extends EventMessage<?>> events)	Publish a collection of events on this bus (one, or multiple).
protected List<EventMessage<?>>	queuedMessages()	Returns a list of all the events staged for publication in this Unit of Work.
Registration	registerDispatchInterceptor(MessageDispatchInterceptor<? super EventMessage<?>> dispatchInterceptor)	Register the given DispatchInterceptor.
Registration	subscribe(Consumer<List<? extends EventMessage<?>>> eventProcessor)	Subscribe the given messageProcessor to this message source.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.eventhandling.EventBus

publish

Constructor Details

AbstractEventBus

protected AbstractEventBus(AbstractEventBus.Builder builder)

Instantiate an AbstractEventBus based on the fields contained in the AbstractEventBus.Builder.

Parameters:

builder - the AbstractEventBus.Builder used to instantiate an AbstractEventBus instance

Method Details

subscribe

public Registration subscribe(@Nonnull
 Consumer<List<? extends EventMessage<?>>> eventProcessor)

Description copied from interface: SubscribableMessageSource

Subscribe the given messageProcessor to this message source. When subscribed, it will receive all messages published to this source.

If the given messageProcessor is already subscribed, nothing happens.

Specified by:

subscribe in interface SubscribableMessageSource<EventMessage<?>>

Parameters:

eventProcessor - The message processor to subscribe

Returns:

a handle to unsubscribe the messageProcessor. When unsubscribed it will no longer receive messages.

registerDispatchInterceptor

public Registration registerDispatchInterceptor(@Nonnull
 MessageDispatchInterceptor<? super EventMessage<?>> dispatchInterceptor)

Register the given DispatchInterceptor. After registration, the interceptor will be invoked for each Message dispatched on the messaging component that it was registered to.

In case a Unit of Work is active, the preprocessor is not invoked by this Event Bus until the Unit of Work root is committed.

Specified by:

registerDispatchInterceptor in interface MessageDispatchInterceptorSupport<EventMessage<?>>

Parameters:

dispatchInterceptor -

Returns:

A Registration, which may be used to deregister the interceptor.

publish

public void publish(@Nonnull
 List<? extends EventMessage<?>> events)

Description copied from interface: EventBus

Publish a collection of events on this bus (one, or multiple). The events will be dispatched to all subscribed listeners.

Implementations may treat the given events as a single batch and distribute the events as such to all subscribed EventListeners.

Specified by:

publish in interface EventBus

Parameters:

events - The collection of events to publish

queuedMessages

protected List<EventMessage<?>> queuedMessages()

Returns a list of all the events staged for publication in this Unit of Work. Changing this list will not affect the publication of events.

Returns:

a list of all the events staged for publication

intercept

protected List<? extends EventMessage<?>> intercept(List<? extends EventMessage<?>> events)

Invokes all the dispatch interceptors.

Parameters:

events - The original events being published

Returns:

The events to actually publish

prepareCommit

protected void prepareCommit(List<? extends EventMessage<?>> events)

Process given events while the Unit of Work root is preparing for commit. The default implementation signals the registered MessageMonitor that the given events are ingested and passes the events to each registered event processor.

Parameters:

events - Events to be published by this Event Bus

commit

protected void commit(List<? extends EventMessage<?>> events)

Process given events while the Unit of Work root is being committed. The default implementation does nothing.

Parameters:

events - Events to be published by this Event Bus

afterCommit

protected void afterCommit(List<? extends EventMessage<?>> events)

Process given events after the Unit of Work has been committed. The default implementation does nothing.

Parameters:

events - Events to be published by this Event Bus