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,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    package org.apache.shiro.authc;
020    
021    /**
022     * <p>An extension of the {@link AuthenticationInfo} interface to be implemented by
023     * classes that support merging with other {@link AuthenticationInfo} instances.</p>
024     *
025     * <p>This allows an instance of this class to be an <em>aggregation</em>, or <em>composition</em> of account data
026     * from across multiple <code>Realm</code>s <tt>Realm</tt>s, not just one realm.</p>
027     *
028     * <p>This is useful in a multi-realm authentication configuration - the individual <tt>AuthenticationInfo</tt>
029     * objects obtained from each realm can be {@link #merge merged} into a single instance.  This instance can then be
030     * returned at the end of the authentication process, giving the impression of a single underlying
031     * realm/data source.
032     *
033     * @since 0.9
034     */
035    public interface MergableAuthenticationInfo extends AuthenticationInfo {
036    
037        /**
038         * Merges the given {@link AuthenticationInfo} into this instance.  The specific way
039         * that the merge occurs is up to the implementation, but typically it involves combining
040         * the principals and credentials together in this instance.  The <code>info</code> argument should
041         * not be modified in any way.
042         *
043         * @param info the info that should be merged into this instance.
044         */
045        void merge(AuthenticationInfo info);
046    
047    }