org.axonframework.eventsourcing

Class FilteringEventStorageEngine

java.lang.Object

org.axonframework.eventsourcing.FilteringEventStorageEngine

All Implemented Interfaces:

EventStorageEngine

public class FilteringEventStorageEngine
extends Object
implements EventStorageEngine

Implementation of EventStorageEngine that delegates to another implementation, while filtering events as they are appended. This prevents certain events to be stored in the Event Store.

Since:

3.1

Author:

Allard Buijze

Constructor Summary

Constructors

Constructor and Description
FilteringEventStorageEngine(EventStorageEngine delegate, Predicate<? super EventMessage<?>> filter) Initializes the FilteringEventStorageEngine delegating all event messages matching the given filter to the given delegate.

Method Summary

Modifier and Type	Method and Description
void	appendEvents(EventMessage<?>... events) Append one or more events to the event storage.
void	appendEvents(List<? extends EventMessage<?>> events) Append a list of events to the event storage.
DomainEventStream	readEvents(String aggregateIdentifier) Get a DomainEventStream containing all events published by the aggregate with given aggregateIdentifier.
DomainEventStream	readEvents(String aggregateIdentifier, long firstSequenceNumber) Get a DomainEventStream containing all events published by the aggregate with given aggregateIdentifier starting with the first event having a sequence number that is equal or larger than the given firstSequenceNumber.
Stream<? extends TrackedEventMessage<?>>	readEvents(TrackingToken trackingToken, boolean mayBlock) Open an event stream containing all events stored since given tracking token.
Optional<DomainEventMessage<?>>	readSnapshot(String aggregateIdentifier) Try to load a snapshot event of the aggregate with given aggregateIdentifier.
void	storeSnapshot(DomainEventMessage<?> snapshot) Store an event that contains a snapshot of an aggregate.

Methods inherited from class java.lang.Object

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

Constructor Detail

FilteringEventStorageEngine

public FilteringEventStorageEngine(EventStorageEngine delegate,
                                   Predicate<? super EventMessage<?>> filter)

Initializes the FilteringEventStorageEngine delegating all event messages matching the given filter to the given delegate.

Note that this only affects events stored in the StorageEngine. The EventStore will still publish these events to Subscribed event handlers. Tracking Event Processors take their events from the stored events, and will therefore not receive any events blocked by this instance.

Parameters:

delegate - the EventStorageEngine to store matching messages in

filter - the predicate that event messages must match against to be stored

Method Detail

appendEvents

public void appendEvents(EventMessage<?>... events)

Description copied from interface: EventStorageEngine

Append one or more events to the event storage. Events will be appended in the order that they are offered in.

Note that all events should have a unique event identifier. When storing domain events events should also have a unique combination of aggregate id and sequence number.

By default this method creates a list of the offered events and then invokes EventStorageEngine.appendEvents(List).

Specified by:

appendEvents in interface EventStorageEngine

Parameters:

events - Events to append to the event storage

appendEvents

public void appendEvents(List<? extends EventMessage<?>> events)

Description copied from interface: EventStorageEngine

Append a list of events to the event storage. Events will be appended in the order that they are offered in.

Note that all events should have a unique event identifier. When storing domain events events should also have a unique combination of aggregate id and sequence number.

Specified by:

appendEvents in interface EventStorageEngine

Parameters:

events - Events to append to the event storage

storeSnapshot

public void storeSnapshot(DomainEventMessage<?> snapshot)

Description copied from interface: EventStorageEngine

Store an event that contains a snapshot of an aggregate. If the event storage already contains a snapshot for the same aggregate, then it will be replaced with the given snapshot.

Specified by:

storeSnapshot in interface EventStorageEngine

Parameters:

snapshot - The snapshot event of the aggregate that is to be stored

readEvents

public Stream<? extends TrackedEventMessage<?>> readEvents(TrackingToken trackingToken,
                                                           boolean mayBlock)

Description copied from interface: EventStorageEngine

Open an event stream containing all events stored since given tracking token. The returned stream is comprised of events from aggregates as well as other application events. Pass a trackingToken of null to open a stream containing all available events.

If the value of the given mayBlock is true the returned stream is allowed to block while waiting for new event messages if the end of the stream is reached.

Specified by:

readEvents in interface EventStorageEngine

Parameters:

trackingToken - Object describing the global index of the last processed event or null to create a stream of all events in the store

mayBlock - If true the storage engine may optionally choose to block to wait for new event messages if the end of the stream is reached.

Returns:

A stream containing all tracked event messages stored since the given tracking token

readEvents

public DomainEventStream readEvents(String aggregateIdentifier)

Description copied from interface: EventStorageEngine

Get a DomainEventStream containing all events published by the aggregate with given aggregateIdentifier. By default calling this method is shorthand for an invocation of EventStorageEngine.readEvents(String, long) with a sequence number of 0.

The returned stream is finite, i.e. it should not block to wait for further events if the end of the event stream of the aggregate is reached.

Specified by:

readEvents in interface EventStorageEngine

Parameters:

aggregateIdentifier - The identifier of the aggregate to return an event stream for

Returns:

A non-blocking DomainEventStream of the given aggregate

readEvents

public DomainEventStream readEvents(String aggregateIdentifier,
                                    long firstSequenceNumber)

Description copied from interface: EventStorageEngine

Get a DomainEventStream containing all events published by the aggregate with given aggregateIdentifier starting with the first event having a sequence number that is equal or larger than the given firstSequenceNumber.

The returned stream is finite, i.e. it should not block to wait for further events if the end of the event stream of the aggregate is reached.

Specified by:

readEvents in interface EventStorageEngine

Parameters:

aggregateIdentifier - The identifier of the aggregate

firstSequenceNumber - The expected sequence number of the first event in the returned stream

Returns:

A non-blocking DomainEventStream of the given aggregate

readSnapshot

public Optional<DomainEventMessage<?>> readSnapshot(String aggregateIdentifier)

Description copied from interface: EventStorageEngine

Try to load a snapshot event of the aggregate with given aggregateIdentifier. If the storage engine has no snapshot event of the aggregate, an empty Optional is returned.

Specified by:

readSnapshot in interface EventStorageEngine

Parameters:

aggregateIdentifier - The identifier of the aggregate

Returns:

An optional with a snapshot of the aggregate