Package org.axonframework.extensions.mongo.eventhandling.saga.repository

Class MongoSagaStore

java.lang.Object
org.axonframework.extensions.mongo.eventhandling.saga.repository.MongoSagaStore
All Implemented Interfaces:
SagaStore<Object>
public class MongoSagaStore extends Object implements SagaStore<Object>
Implementations of the SagaRepository that stores Sagas and their associations in a Mongo Database. Each Saga and its associations is stored as a single document.

The document layout is that of Axon Framework 4, so an existing sagas collection can be read and updated without migration, provided its sagaType field holds saga class names. Axon Framework 4 derived that field through its Serializer, which for the default configuration also produced the class name. An application that mapped its saga classes to some other type name, an XStream alias being the usual way, has documents this store cannot route to and must rewrite that field to the class name first.

The saga state itself is converted with the configured Converter. Axon Framework 4 defaulted to the XStreamSerializer unless the application configured another serializer, so the stored state of such an application is XStream XML, which a JSON-based converter cannot read: loading such a saga fails. Give this store an XStreamConverter if you are migrating such a scenario to read that state and to write it back in the same form, which also lets Axon Framework 4 nodes keep handling the same sagas during a rolling upgrade.

Note that sagaType records the class of the saga instance handed to insertSaga(Class, String, Object, Set), which is not necessarily the sagaType argument. Loading, on the other hand, matches on the identifier alone and ignores the type entirely.

This store performs one Mongo operation per call, so it manages no transaction of its own beyond whatever the TransactionManager it was given provides. That defaults to NoTransactionManager, as it did in Axon Framework 4, under which a call commits on its own.

Since:
2.0
Author:
Jettro Coenradie, Allard Buijze

  • Constructor Details

  • Method Details

    • builder

      public static MongoSagaStore.Builder builder()
      Instantiate a Builder to be able to create a MongoSagaStore.

      The MongoTemplate and Converter are hard requirements and as such should be provided. The TransactionManager is defaulted to a NoTransactionManager.

      Returns:
      a Builder to be able to create a MongoSagaStore

    • loadSaga

      public <S> @Nullable SagaStore.Entry<S> loadSaga(Class<S> sagaType, String sagaIdentifier)
      Description copied from interface: SagaStore
      Loads a known saga SagaStore.Entry instance with given sagaType and unique sagaIdentifier.

      Due to the concurrent nature of Sagas, it is not unlikely for a Saga to have ceased to exist after it has been found based on associations. Therefore, a repository should return null in case a Saga doesn't exists, as opposed to throwing an exception.

      Specified by:
      loadSaga in interface SagaStore<Object>
      Type Parameters:
      S - the specific saga type returned
      Parameters:
      sagaType - The type of the returned saga entry
      sagaIdentifier - The unique identifier of the returned saga entry
      Returns:
      The saga entry, or null if no such saga exists

    • findSagas

      public Set<String> findSagas(Class<?> sagaType, AssociationValue associationValue)
      Description copied from interface: SagaStore
      Returns identifiers of saga instances of the given sagaType that have been associated with the given associationValue.
      Specified by:
      findSagas in interface SagaStore<Object>
      Parameters:
      sagaType - The type of the returned sagas
      associationValue - The value that the returned sagas must be associated with
      Returns:
      A set of identifiers of sagas having the correct type and association value

    • deleteSaga

      public void deleteSaga(Class<?> sagaType, String sagaIdentifier, Set<AssociationValue> associationValues)
      Description copied from interface: SagaStore
      Deletes a Saga with given sagaType and sagaIdentifier and all its associations. For convenience all known association values are passed along as well, which has the advantage that the saga store is not required to keep an index of association value to saga identifier.
      Specified by:
      deleteSaga in interface SagaStore<Object>
      Parameters:
      sagaType - The type of saga to delete
      sagaIdentifier - The identifier of the saga to delete
      associationValues - The known associations of the saga

    • updateSaga

      public void updateSaga(Class<?> sagaType, String sagaIdentifier, Object saga, AssociationValues associationValues)
      Description copied from interface: SagaStore
      Updates a given Saga after its state was modified, applying the association values added and removed since it was last stored.
      Specified by:
      updateSaga in interface SagaStore<Object>
      Parameters:
      sagaType - The type of the Saga
      sagaIdentifier - The identifier of the Saga
      saga - The Saga instance
      associationValues - The association values of the Saga, carrying the additions and removals to apply

    • insertSaga

      public void insertSaga(Class<?> sagaType, String sagaIdentifier, Object saga, Set<AssociationValue> associationValues)
      Description copied from interface: SagaStore
      Adds a new Saga and its initial association values to the store.
      Specified by:
      insertSaga in interface SagaStore<Object>
      Parameters:
      sagaType - The type of the Saga
      sagaIdentifier - The identifier of the Saga
      saga - The Saga instance
      associationValues - The initial association values of the Saga