content: /**
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.apache.ambari.view;
  
  import java.util.Collection;
  
  /**
   * View data store.
   */
  public interface DataStore {
  
    /**
     * Save the given entity to persistent storage.  The entity must be declared as an
     * {@code <entity>} in the {@code <persistence>} element of the view.xml.
     *
     * @param entity  the entity to be persisted.
     *
     * @throws PersistenceException thrown if the given entity can not be persisted
     */
    public void store(Object entity) throws PersistenceException;
  
    /**
     * Remove the given entity from persistent storage.
     *
     * @param entity  the entity to be removed.
     *
     * @throws PersistenceException thrown if the given entity can not be removed
     */
    public void remove(Object entity) throws PersistenceException;
  
    /**
     * Find the entity of the given class type that is uniquely identified by the
     * given primary key.
     *
     * @param clazz       the entity class
     * @param primaryKey  the primary key
     * @param <T>         the entity type
     *
     * @return the entity; null if the entity can't be found
     *
     * @throws PersistenceException thrown if an error occurs trying to find the entity
     */
    public <T> T find(Class<T> clazz, Object primaryKey) throws PersistenceException;
  
    /**
     * Find all the entities for the given where clause.  Specifying null for the where
     * clause should return all entities of the given class type.
     *
     * @param clazz        the entity class
     * @param whereClause  the where clause; may be null
     * @param <T>          the entity type
     *
     * @return all of the entities for the given where clause; empty collection if no
     *         entities can be found
     *
     * @throws PersistenceException
     */
    public <T> Collection<T> findAll(Class<T> clazz, String whereClause) throws PersistenceException;
  }
  