001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.security;
019
020import java.io.IOException;
021import java.util.List;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025
026/**
027 * An interface for the implementation of a user-to-groups mapping service
028 * used by {@link Groups}.
029 */
030@InterfaceAudience.Public
031@InterfaceStability.Evolving
032public interface GroupMappingServiceProvider {
033  
034  /**
035   * Get all various group memberships of a given user.
036   * Returns EMPTY list in case of non-existing user
037   * @param user User's name
038   * @return group memberships of user
039   * @throws IOException
040   */
041  public List<String> getGroups(String user) throws IOException;
042  /**
043   * Refresh the cache of groups and user mapping
044   * @throws IOException
045   */
046  public void cacheGroupsRefresh() throws IOException;
047  /**
048   * Caches the group user information
049   * @param groups list of groups to add to cache
050   * @throws IOException
051   */
052  public void cacheGroupsAdd(List<String> groups) throws IOException;
053}