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