org.axonframework.eventsourcing
Class AbstractEventSourcedAggregateRoot

java.lang.Object
  org.axonframework.domain.AbstractAggregateRoot
      org.axonframework.eventsourcing.AbstractEventSourcedAggregateRoot

All Implemented Interfaces:

Serializable, AggregateRoot, EventSourcedAggregateRoot

Direct Known Subclasses:

AbstractAnnotatedAggregateRoot

public abstract class AbstractEventSourcedAggregateRoot
extends AbstractAggregateRoot
implements EventSourcedAggregateRoot

Abstract convenience class to be extended by all aggregate roots. The AbstractEventSourcedAggregateRoot tracks all uncommitted events. It also provides convenience methods to initialize the state of the aggregate root based on a DomainEventStream, which can be used for event sourcing.

Since:

0.1

Author:

Allard Buijze

See Also:

Serialized Form

Constructor Summary

protected	AbstractEventSourcedAggregateRoot() Initializes the aggregate root using a random aggregate identifier.
protected	AbstractEventSourcedAggregateRoot(AggregateIdentifier identifier) Initializes the aggregate root using the provided aggregate identifier.
protected	AbstractEventSourcedAggregateRoot(UUID identifier) Deprecated. Use AbstractEventSourcedAggregateRoot(org.axonframework.domain.AggregateIdentifier). Will be removed in next release.

Method Summary

protected void	apply(DomainEvent event) Apply the provided event.
protected Collection<AbstractEventSourcedEntity>	getChildEntities() Returns a list of event sourced entities directly referenced by the aggregate root.
protected abstract void	handle(DomainEvent event) Apply state changes based on the given event.
void	initializeState(DomainEventStream domainEventStream) Initialize the state of this aggregate using the events in the provided DomainEventStream.

Methods inherited from class org.axonframework.domain.AbstractAggregateRoot

commitEvents, getIdentifier, getUncommittedEventCount, getUncommittedEvents, getVersion, initializeEventStream, registerEvent

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.axonframework.domain.AggregateRoot

commitEvents, getIdentifier, getUncommittedEventCount, getUncommittedEvents, getVersion

Constructor Detail

AbstractEventSourcedAggregateRoot

protected AbstractEventSourcedAggregateRoot()

Initializes the aggregate root using a random aggregate identifier.

AbstractEventSourcedAggregateRoot

protected AbstractEventSourcedAggregateRoot(AggregateIdentifier identifier)

Initializes the aggregate root using the provided aggregate identifier.

Parameters:

identifier - the identifier of this aggregate

AbstractEventSourcedAggregateRoot

@Deprecated
protected AbstractEventSourcedAggregateRoot(UUID identifier)

Deprecated. Use AbstractEventSourcedAggregateRoot(org.axonframework.domain.AggregateIdentifier). Will be removed in next release.

Initializes the aggregate root using the provided aggregate identifier.

Parameters:

identifier - the identifier of this aggregate

Method Detail

initializeState

public void initializeState(DomainEventStream domainEventStream)

Initialize the state of this aggregate using the events in the provided DomainEventStream. A call to this method on an aggregate that has already been initialized will result in an IllegalStateException.

This implementation is aware of two special types of DomainEvents: The AggregateDeletedEvent, which indicates that the aggregate is deleted and the AggregateSnapshot, which is a snapshot event, containing the actual aggregate inside.

When an AggregateDeletedEvent is encountered, a AggregateDeletedException is thrown, unless there are events following the AggregateDeletedEvent. This could be the case when an event is added to the stream as a correction to an earlier event.

AggregateSnapshot events are used to initialize the aggregate with the correct version (AbstractAggregateRoot.getVersion()).

Specified by:

initializeState in interface EventSourcedAggregateRoot

Parameters:

domainEventStream - the event stream containing the events that describe the state changes of this aggregate

Throws:

IllegalStateException - if this aggregate was already initialized.

AggregateDeletedException - if the event stream contains an event of type AggregateDeletedEvent (or subtype).

apply

protected void apply(DomainEvent event)

Apply the provided event. Applying events means they are added to the uncommitted event queue and forwarded to the handle(DomainEvent) event handler method} for processing.

The event is applied on all entities part of this aggregate.

Parameters:

event - The event to apply

getChildEntities

protected Collection<AbstractEventSourcedEntity> getChildEntities()

Returns a list of event sourced entities directly referenced by the aggregate root.

The default implementation uses reflection to find references to AbstractEventSourcedEntity implementations.

It will look for entities:

• directly referenced in a field;
• inside fields containing an Iterable;
• inside both they keys and the values of fields containing a Map

Returns:

a list of event sourced entities contained in this aggregate

handle

protected abstract void handle(DomainEvent event)

Apply state changes based on the given event.

Note: Implementations of this method should *not* perform validation.

Parameters:

event - The event to handle