org.axonframework.eventstore.mongo

Class DocumentPerEventStorageStrategy

java.lang.Object

org.axonframework.eventstore.mongo.DocumentPerEventStorageStrategy

All Implemented Interfaces:

StorageStrategy

public class DocumentPerEventStorageStrategy
extends Object
implements StorageStrategy

Implementation of the StorageStrategy that stores each event as a separate document. This makes it easier to query the event store for specific events, but does not allow for atomic storage of a single commit.

The structure is as follows:

• aggregateIdentifier => [aggregateIdentifier]
• sequenceNumber => [sequenceNumber of first event]
• timestamp => [timestamp of first event]
• type => [aggregate type]
• serializedPayload => [payload of the event]
• payloadType => [type of the payload]
• payloadRevision => [revision of the payload]
• serializedMetaData => [meta data of the event]
• eventIdentifier => [identifier of the event]

Note: the SerializedType of Message Meta Data is not stored. Upon retrieval, it is set to the default value (name = "org.axonframework.domain.MetaData", revision = null).

Since:

2.0

Author:

Allard Buijze

Constructor Summary

Constructors

Constructor and Description
DocumentPerEventStorageStrategy()

Method Summary

Methods

Modifier and Type	Method and Description
com.mongodb.DBObject[]	createDocuments(String type, Serializer eventSerializer, List<DomainEventMessage> messages) Generates the DBObject instances that need to be stored for a commit.
void	ensureIndexes(com.mongodb.DBCollection eventsCollection, com.mongodb.DBCollection snapshotsCollection) Ensure that the correct indexes are in place.
List<DomainEventMessage>	extractEventMessages(com.mongodb.DBObject entry, Object aggregateIdentifier, Serializer serializer, UpcasterChain upcasterChain) Extracts the individual Event Messages from the given entry.
com.mongodb.DBCursor	findEvents(com.mongodb.DBCollection collection, MongoCriteria criteria) Find all events that match the given criteria in the given collection
com.mongodb.DBCursor	findEvents(com.mongodb.DBCollection collection, String aggregateType, String aggregateIdentifier, long firstSequenceNumber) Provides a cursor for access to all events for an aggregate with given aggregateType and aggregateIdentifier, with a sequence number equal or higher than the given firstSequenceNumber.
com.mongodb.DBCursor	findLastSnapshot(com.mongodb.DBCollection collection, String aggregateType, String aggregateIdentifier) Finds the entry containing the last snapshot event for an aggregate with given aggregateType and aggregateIdentifier in the given collection.

Methods inherited from class java.lang.Object

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

Constructor Detail

DocumentPerEventStorageStrategy

public DocumentPerEventStorageStrategy()

Method Detail

createDocuments

public com.mongodb.DBObject[] createDocuments(String type,
                                     Serializer eventSerializer,
                                     List<DomainEventMessage> messages)

Description copied from interface: StorageStrategy

Generates the DBObject instances that need to be stored for a commit.

Specified by:

createDocuments in interface StorageStrategy

Parameters:

type - The aggregate's type identifier

eventSerializer - The serializer to serialize events with

messages - The messages contained in this commit

Returns:

an array of DBObject, representing the documents to store

findEvents

public com.mongodb.DBCursor findEvents(com.mongodb.DBCollection collection,
                              String aggregateType,
                              String aggregateIdentifier,
                              long firstSequenceNumber)

Description copied from interface: StorageStrategy

Provides a cursor for access to all events for an aggregate with given aggregateType and aggregateIdentifier, with a sequence number equal or higher than the given firstSequenceNumber. The returned documents should be ordered chronologically (typically by using the sequence number).

Each DBObject document returned as result of this cursor will be passed to StorageStrategy.extractEventMessages(com.mongodb.DBObject, java.lang.Object, org.axonframework.serializer.Serializer, org.axonframework.upcasting.UpcasterChain) in order to retrieve individual DomainEventMessages.

Specified by:

findEvents in interface StorageStrategy

Parameters:

collection - The collection to

aggregateType - The type identifier of the aggregate to query

aggregateIdentifier - The identifier of the aggregate to query

firstSequenceNumber - The sequence number of the first event to return

Returns:

a Query object that represent a query for events of an aggregate

extractEventMessages

public List<DomainEventMessage> extractEventMessages(com.mongodb.DBObject entry,
                                            Object aggregateIdentifier,
                                            Serializer serializer,
                                            UpcasterChain upcasterChain)

Description copied from interface: StorageStrategy

Extracts the individual Event Messages from the given entry. The aggregateIdentifier is passed to allow messages to contain the actual object, instead of its serialized form. The serializer and upcasterChain should be used to deserialize and upcast messages before returning them.

Specified by:

extractEventMessages in interface StorageStrategy

Parameters:

entry - The entry containing information of a stored commit

aggregateIdentifier - The aggregate identifier used to query events

serializer - The serializer to deserialize events with

upcasterChain - The upcaster chain to upcast stored events with

Returns:

a list of DomainEventMessage contained in the entry

ensureIndexes

public void ensureIndexes(com.mongodb.DBCollection eventsCollection,
                 com.mongodb.DBCollection snapshotsCollection)

Description copied from interface: StorageStrategy

Ensure that the correct indexes are in place.

Specified by:

ensureIndexes in interface StorageStrategy

Parameters:

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

snapshotsCollection - The collection containing the document representing snapshots

findEvents

public com.mongodb.DBCursor findEvents(com.mongodb.DBCollection collection,
                              MongoCriteria criteria)

Description copied from interface: StorageStrategy

Find all events that match the given criteria in the given collection

Specified by:

findEvents in interface StorageStrategy

Parameters:

collection - The collection to search for events

criteria - The criteria to match against the events

Returns:

a cursor for the documents representing matched events

findLastSnapshot

public com.mongodb.DBCursor findLastSnapshot(com.mongodb.DBCollection collection,
                                    String aggregateType,
                                    String aggregateIdentifier)

Description copied from interface: StorageStrategy

Finds the entry containing the last snapshot event for an aggregate with given aggregateType and aggregateIdentifier in the given collection. For each result returned by the Cursor, an invocation to StorageStrategy.extractEventMessages(com.mongodb.DBObject, java.lang.Object, org.axonframework.serializer.Serializer, org.axonframework.upcasting.UpcasterChain) will be used to extract the actual DomainEventMessages.

Specified by:

findLastSnapshot in interface StorageStrategy

Parameters:

collection - The collection to find the last snapshot event in

aggregateType - The type identifier of the aggregate to find a snapshot for

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

Returns:

a cursor providing access to the entries found