org.axonframework.mongo.eventsourcing.eventstore

Interface StorageStrategy

All Known Implementing Classes:

AbstractMongoEventStorageStrategy, DocumentPerCommitStorageStrategy, DocumentPerEventStorageStrategy

public interface StorageStrategy

Interface towards the mechanism that prescribes the structure in which events are stored in the Event Store. Events are provided in "commits", which represent a number of events generated by the same aggregate, inside a single Unit of Work. Implementations may choose to use this fact, or ignore it.

Author:

Allard Buijze, Rene de Waele

Method Summary

Modifier and Type	Method and Description
void	appendEvents(com.mongodb.client.MongoCollection<org.bson.Document> eventCollection, List<? extends EventMessage<?>> events, Serializer serializer) Appends the given list of events to the given eventCollection.
void	appendSnapshot(com.mongodb.client.MongoCollection<org.bson.Document> snapshotCollection, DomainEventMessage<?> snapshot, Serializer serializer) Append the given aggregate snapshot to the snapshotCollection.
TrackingToken	createTailToken(com.mongodb.client.MongoCollection<org.bson.Document> eventsCollection) Creates a token that is at the tail of an event stream - that tracks events from the beginning of time.
void	deleteSnapshots(com.mongodb.client.MongoCollection<org.bson.Document> snapshotCollection, String aggregateIdentifier, long sequenceNumber) Delete all snapshots of the aggregate with given aggregateIdentifier from the given snapshotCollection, whose sequence number is lower than the given sequenceNumber.
void	ensureIndexes(com.mongodb.client.MongoCollection<org.bson.Document> eventsCollection, com.mongodb.client.MongoCollection<org.bson.Document> snapshotsCollection) Ensure that the correct indexes are in place.
List<? extends DomainEventData<?>>	findDomainEvents(com.mongodb.client.MongoCollection<org.bson.Document> eventCollection, String aggregateIdentifier, long firstSequenceNumber, int batchSize) Returns a batch of events for an aggregate with given aggregateIdentifier and a sequence number equal or higher than the given firstSequenceNumber.
Optional<? extends DomainEventData<?>>	findLastSnapshot(com.mongodb.client.MongoCollection<org.bson.Document> snapshotCollection, String aggregateIdentifier) Finds the entry containing the last snapshot event for an aggregate with given aggregateIdentifier in the given collection.
List<? extends TrackedEventData<?>>	findTrackedEvents(com.mongodb.client.MongoCollection<org.bson.Document> eventCollection, TrackingToken lastToken, int batchSize) Returns a batch of tracked events with a tracking token above the given lastToken.
Optional<Long>	lastSequenceNumberFor(com.mongodb.client.MongoCollection<org.bson.Document> eventsCollection, String aggregateIdentifier) Return the last known sequence number for an Aggregate with given aggregateIdentifier, whose Events are stored in the given eventsCollection.

Method Detail

appendEvents

void appendEvents(com.mongodb.client.MongoCollection<org.bson.Document> eventCollection,
                  List<? extends EventMessage<?>> events,
                  Serializer serializer)

Appends the given list of events to the given eventCollection. Use the given serializer to serialize the payload and metadata of the events.

Parameters:

eventCollection - the document collection that contains event entries

events - the event messages to append to the event collection

serializer - the serializer used to serialize the event payload and metadata

appendSnapshot

void appendSnapshot(com.mongodb.client.MongoCollection<org.bson.Document> snapshotCollection,
                    DomainEventMessage<?> snapshot,
                    Serializer serializer)

Append the given aggregate snapshot to the snapshotCollection. Use the given serializer to serialize the payload and metadata of the snapshot.

Parameters:

snapshotCollection - the document collection that contains aggregate snapshot entries

snapshot - the snapshot event message to append to the event collection

serializer - the serializer used to serialize the payload and metadata of the snapshot event

deleteSnapshots

void deleteSnapshots(com.mongodb.client.MongoCollection<org.bson.Document> snapshotCollection,
                     String aggregateIdentifier,
                     long sequenceNumber)

Delete all snapshots of the aggregate with given aggregateIdentifier from the given snapshotCollection, whose sequence number is lower than the given sequenceNumber.

Parameters:

snapshotCollection - the document collection that contains aggregate snapshot entries

aggregateIdentifier - the identifier of the aggregate for which to delete all snapshots

sequenceNumber - The sequenceNumber representing the upper bound (exclusive) of the snapshots to delete

findDomainEvents

List<? extends DomainEventData<?>> findDomainEvents(com.mongodb.client.MongoCollection<org.bson.Document> eventCollection,
                                                    String aggregateIdentifier,
                                                    long firstSequenceNumber,
                                                    int batchSize)

Returns a batch of events for an aggregate with given aggregateIdentifier and a sequence number equal or higher than the given firstSequenceNumber. The returned documents should be ordered chronologically (typically by using the sequence number). The size of the returned list should not exceed the given batchSize.

Parameters:

eventCollection - The collection in which to find the events

aggregateIdentifier - The identifier of the aggregate to query

firstSequenceNumber - The sequence number of the first event to return

batchSize - The maximum number of event entries to fetch

Returns:

a list of matching domain event entries

findTrackedEvents

List<? extends TrackedEventData<?>> findTrackedEvents(com.mongodb.client.MongoCollection<org.bson.Document> eventCollection,
                                                      TrackingToken lastToken,
                                                      int batchSize)

Returns a batch of tracked events with a tracking token above the given lastToken. If lastToken is null the first (oldest) batch of entries in the store should be returned.

The returned documents should be ordered chronologically (typically by using the timestamp of the event). The size of the returned list should not exceed the given batchSize.

Parameters:

eventCollection - The collection in which to find the events

lastToken - the token of the last event in the previous batch or null to load the oldest batch

batchSize - The maximum number of event entries to fetch

Returns:

a list of matching tracked event entries

findLastSnapshot

Optional<? extends DomainEventData<?>> findLastSnapshot(com.mongodb.client.MongoCollection<org.bson.Document> snapshotCollection,
                                                        String aggregateIdentifier)

Finds the entry containing the last snapshot event for an aggregate with given aggregateIdentifier in the given collection.

Parameters:

snapshotCollection - The collection to find the last snapshot event in

aggregateIdentifier - The identifier of the aggregate to find a snapshot for

Returns:

an optional with DomainEventData of the snapshot if found

ensureIndexes

void ensureIndexes(com.mongodb.client.MongoCollection<org.bson.Document> eventsCollection,
                   com.mongodb.client.MongoCollection<org.bson.Document> snapshotsCollection)

Ensure that the correct indexes are in place.

Parameters:

eventsCollection - The collection containing the documents representing commits and events.

snapshotsCollection - The collection containing the document representing snapshots

lastSequenceNumberFor

Optional<Long> lastSequenceNumberFor(com.mongodb.client.MongoCollection<org.bson.Document> eventsCollection,
                                     String aggregateIdentifier)

Return the last known sequence number for an Aggregate with given aggregateIdentifier, whose Events are stored in the given eventsCollection.

Parameters:

eventsCollection - The Collection in which to search for Events

aggregateIdentifier - The aggregate to find the last sequence number for

Returns:

An optional with the last sequence number, or an empty optional if no Events are present for the given aggregate.

createTailToken

TrackingToken createTailToken(com.mongodb.client.MongoCollection<org.bson.Document> eventsCollection)

Creates a token that is at the tail of an event stream - that tracks events from the beginning of time.

Returns:

a tracking token at the tail of an event stream, if event stream is empty null is returned