Package com.ibm.websphere.objectgrid.em

This package contains the primary interfaces for the EntityManager.

See:
Description

Interface Summary

EntityManager	An EntityManager allows transactional introspection and manipulation of entities.
EntityTransaction	An EntityTransaction is associated with an EntityManager and is used to demarcate a transaction.
Query	Interface used to control entity query execution.
QueryQueue	A query queue allows users to get entities qualified by a query in an iterative manner.

Class Summary

FlushModeType	Used to specify when the flush behavior of an EntityManager query when running within a transaction.
ProjectorFactory	A factory for creating or retrieving Projector instances.

Exception Summary

EntityExistsException	Thrown when an entity can't be persisted because it would result in a duplicate key violation.
NonUniqueResultException	Thrown when Query.getSingleResult() is invoked and there is more than one result from the query.
NoResultException	Thrown when Query.getSingleResult() is invoked and there is no result to return.
OptimisticLockException	Thrown when there is an optimistic collision when merging, flushing or committing an entity that has an out of date version mismatch.
PersistenceException	Thrown by the EntityManager when a problem occurs.
RollbackException	Thrown when EntityTransaction.commit() fails.
TransactionRequiredException	Thrown when a transaction is required but not active.

Package com.ibm.websphere.objectgrid.em Description

This package contains the primary interfaces for the EntityManager.

Overview

The EntityManager API allows simplified access to the ObjectGrid data cache. Java classes are described using annotations or XML as entities. Entities are Java objects that contain persistable attributes and relationships to other entities. The entities can be persisted into the cache and queried using the ObjectGrid Query Language.

The EntityManager API is much simpler to use than the ObjectMap API as it handles many of the relationship management tasks that would normally need to be done manually when using the ObjectMap API. The EntityManager utilizes ObjectGrid maps by using Tuple objects. Each entity is associated with a single BackingMap that matches the entity's simple class name. The data within the entity is converted to a key tuple and a value tuple and the tuples are inserted into the map. The EntityManager automatically converts entities to and from tuples and interacts with the maps when needed.

Use the ProjectorFactory to access a Projector for advanced functionality.

See Also:

com.ibm.websphere.projector