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Basic JPA2 services for Tapestry IoC

There is a newer version: 2.0.1

// Copyright 2007, 2008 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.tynamo.jpa;

import javax.persistence.EntityManager;

/**
 * Manages the JPA transaction for the current thread. This includes creating an entity manager as
 * needed, allowing the em to checkpoint (commit the current transaction and continue) and commit
 * the transaction automatically at the end of the request.
 * 
 * Remember that in Tapestry, action requests and render requests are entirely separate, and you
 * will see a separate request and a separate transaction for each. Care should be taken to ensure
 * that entity objects that are retained (in the session, as persistent field values) between
 * requests are handled correctly (they tend to become detached instances).
 * 
 * This implementation of this service is per-thread.
 */
public interface JPATransactionManager
{
	/**
	 * Gets the active session for this request, creating it as necessary. When the session is first
	 * created, a transaction is started.
	 * 
	 * @return the request's entityManager
	 * @see JPAEntityManagerSource
	 */
	EntityManager getEntityManager();

	/**
	 * Commits the current transaction (which will cause a flush of data to the database), then
	 * starts a new transaction to replace it.
	 */
	void commit();

	/**
	 * Aborts the current transaction, and starts a new transaction to replace it.
	 */
	void abort();
}