Package org.axonframework.eventsourcing.eventstore

Class AbstractEventStorageEngine

java.lang.Object
org.axonframework.eventsourcing.eventstore.AbstractEventStorageEngine
All Implemented Interfaces:
EventStorageEngine
Direct Known Subclasses:
BatchingEventStorageEngine
public abstract class AbstractEventStorageEngine extends Object implements EventStorageEngine
Abstract EventStorageEngine implementation that takes care of event serialization and upcasting.
Since:
3.0
Author:
Rene de Waele

  • Field Details

  • Constructor Details

  • Method Details

    • 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(@Nonnull 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(@Nonnull 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

    • appendEvents

      public void appendEvents(@Nonnull 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(@Nonnull 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

    • handlePersistenceException

      protected void handlePersistenceException(Exception exception, EventMessage<?> failedEvent)
      Invoke when an Exception is raised while persisting an Event or Snapshot.
      Parameters:
      exception - The exception raised while persisting an Event
      failedEvent - The EventMessage that could not be persisted

    • appendEvents

      protected abstract void appendEvents(List<? extends EventMessage<?>> events, Serializer serializer)
      Append given events to the backing database. Use the given serializer to serialize the event's payload and metadata.
      Parameters:
      events - Events to append to the database
      serializer - Serializer used to convert the events to a suitable format for storage

    • storeSnapshot

      protected abstract void storeSnapshot(DomainEventMessage<?> snapshot, Serializer serializer)
      Store the given snapshot of an Aggregate. Implementations may override any existing snapshot of the Aggregate with the given snapshot.
      Parameters:
      snapshot - Snapshot Event of the aggregate
      serializer - Serializer used to convert the snapshot event to a suitable format for storage

    • readEventData

      protected abstract Stream<? extends DomainEventData<?>> readEventData(String identifier, long firstSequenceNumber)
      Returns a Stream of serialized event data entries for an aggregate with given identifier. The events should be ordered by aggregate sequence number and have a sequence number starting from the given firstSequenceNumber.
      Parameters:
      identifier - The identifier of the aggregate to open a stream for
      firstSequenceNumber - The sequence number of the first excepted event entry
      Returns:
      a Stream of serialized event entries for the given aggregate

    • readEventData

      protected abstract Stream<? extends TrackedEventData<?>> readEventData(TrackingToken trackingToken, boolean mayBlock)
      Returns a global Stream containing all serialized event data entries in the event storage that have a TrackingToken greater than the given trackingToken. Event entries in the stream should be ordered by tracking token. If the trackingToken is null a stream containing all events should be returned.

      If the end of the stream is reached and mayBlock is true the stream may block to wait for new events.

      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

    • readSnapshotData

      protected abstract Stream<? extends DomainEventData<?>> readSnapshotData(String aggregateIdentifier)
      Returns a stream of serialized event entries for given aggregateIdentifier if the backing database contains a snapshot of the aggregate.

      It is required that specific event storage engines return snapshots in descending order of their sequence number.

      Parameters:
      aggregateIdentifier - The aggregate identifier to fetch a snapshot for
      Returns:
      A stream of serialized snapshots of the aggregate

    • getSnapshotSerializer

      public Serializer getSnapshotSerializer()
      Get the serializer used by this storage engine when storing and retrieving snapshots.
      Returns:
      the serializer used by this storage

    • getEventSerializer

      public Serializer getEventSerializer()
      Get the serializer used by this storage engine when storing and retrieving events.
      Returns:
      the serializer used by this storage