001// Copyright 2011 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.jpa;
016
017import java.util.Map;
018
019import javax.persistence.EntityManager;
020
021/**
022 * Manages <code>EntityManager</code>s for the current thread.
023 * An <code>EntityManager</code> is created as needed and closed at the end of each request.
024 *
025 * <p/>
026 *
027 * The implementation of this service is per-thread.
028 *
029 * @since 5.3
030 */
031public interface EntityManagerManager
032{
033    /**
034     * Gets the active <code>EntityManager</code> for this request, creating it as necessary.
035     *
036     * @param persistenceUnitName the name of a persistence unit as defined in <code>persistence.xml<code>
037     * @return EntityManager for the persistence unit,
038     */
039    EntityManager getEntityManager(String persistenceUnitName);
040
041    /**
042     * Gets all active <code>EntityManager</code>s for this request, creating them as necessary.
043     *
044     * @return Map in which persistence unit names are associated with EntityManagers
045     */
046    Map<String, EntityManager> getEntityManagers();
047}