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    
015    package org.apache.tapestry5.jpa;
016    
017    import java.util.Map;
018    
019    import 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     */
031    public 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    }