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 */
019package org.apache.shiro.session.mgt.eis;
020
021import org.apache.shiro.session.Session;
022import org.apache.shiro.session.UnknownSessionException;
023
024import java.io.Serializable;
025import java.util.Collection;
026
027
028/**
029 * Data Access Object design pattern specification to enable {@link Session} access to an
030 * EIS (Enterprise Information System).  It provides your four typical CRUD methods:
031 * {@link #create}, {@link #readSession(java.io.Serializable)}, {@link #update(org.apache.shiro.session.Session)},
032 * and {@link #delete(org.apache.shiro.session.Session)}.
033 * <p/>
034 * The remaining {@link #getActiveSessions()} method exists as a support mechanism to pre-emptively orphaned sessions,
035 * typically by {@link org.apache.shiro.session.mgt.ValidatingSessionManager ValidatingSessionManager}s), and should
036 * be as efficient as possible, especially if there are thousands of active sessions.  Large scale/high performance
037 * implementations will often return a subset of the total active sessions and perform validation a little more
038 * frequently, rather than return a massive set and infrequently validate.
039 *
040 * @since 0.1
041 */
042public interface SessionDAO {
043
044    /**
045     * Inserts a new Session record into the underling EIS (e.g. Relational database, file system, persistent cache,
046     * etc, depending on the DAO implementation).
047     * <p/>
048     * After this method is invoked, the {@link org.apache.shiro.session.Session#getId()}
049     * method executed on the argument must return a valid session identifier.  That is, the following should
050     * always be true:
051     * <pre>
052     * Serializable id = create( session );
053     * id.equals( session.getId() ) == true</pre>
054     * <p/>
055     * Implementations are free to throw any exceptions that might occur due to
056     * integrity violation constraints or other EIS related errors.
057     *
058     * @param session the {@link org.apache.shiro.session.Session} object to create in the EIS.
059     * @return the EIS id (e.g. primary key) of the created {@code Session} object.
060     */
061    Serializable create(Session session);
062
063    /**
064     * Retrieves the session from the EIS uniquely identified by the specified
065     * {@code sessionId}.
066     *
067     * @param sessionId the system-wide unique identifier of the Session object to retrieve from
068     *                  the EIS.
069     * @return the persisted session in the EIS identified by {@code sessionId}.
070     * @throws UnknownSessionException if there is no EIS record for any session with the
071     *                                 specified {@code sessionId}
072     */
073    Session readSession(Serializable sessionId) throws UnknownSessionException;
074
075    /**
076     * Updates (persists) data from a previously created Session instance in the EIS identified by
077     * {@code {@link Session#getId() session.getId()}}.  This effectively propagates
078     * the data in the argument to the EIS record previously saved.
079     * <p/>
080     * In addition to UnknownSessionException, implementations are free to throw any other
081     * exceptions that might occur due to integrity violation constraints or other EIS related
082     * errors.
083     *
084     * @param session the Session to update
085     * @throws org.apache.shiro.session.UnknownSessionException
086     *          if no existing EIS session record exists with the
087     *          identifier of {@link Session#getId() session.getSessionId()}
088     */
089    void update(Session session) throws UnknownSessionException;
090
091    /**
092     * Deletes the associated EIS record of the specified {@code session}.  If there never
093     * existed a session EIS record with the identifier of
094     * {@link Session#getId() session.getId()}, then this method does nothing.
095     *
096     * @param session the session to delete.
097     */
098    void delete(Session session);
099
100    /**
101     * Returns all sessions in the EIS that are considered active, meaning all sessions that
102     * haven't been stopped/expired.  This is primarily used to validate potential orphans.
103     * <p/>
104     * If there are no active sessions in the EIS, this method may return an empty collection or {@code null}.
105     * <h4>Performance</h4>
106     * This method should be as efficient as possible, especially in larger systems where there might be
107     * thousands of active sessions.  Large scale/high performance
108     * implementations will often return a subset of the total active sessions and perform validation a little more
109     * frequently, rather than return a massive set and validate infrequently.  If efficient and possible, it would
110     * make sense to return the oldest unstopped sessions available, ordered by
111     * {@link org.apache.shiro.session.Session#getLastAccessTime() lastAccessTime}.
112     * <h4>Smart Results</h4>
113     * <em>Ideally</em> this method would only return active sessions that the EIS was certain should be invalided.
114     * Typically that is any session that is not stopped and where its lastAccessTimestamp is older than the session
115     * timeout.
116     * <p/>
117     * For example, if sessions were backed by a relational database or SQL-92 'query-able' enterprise cache, you might
118     * return something similar to the results returned by this query (assuming
119     * {@link org.apache.shiro.session.mgt.SimpleSession SimpleSession}s were being stored):
120     * <pre>
121     * select * from sessions s where s.lastAccessTimestamp < ? and s.stopTimestamp is null
122     * </pre>
123     * where the {@code ?} parameter is a date instance equal to 'now' minus the session timeout
124     * (e.g. now - 30 minutes).
125     *
126     * @return a Collection of {@code Session}s that are considered active, or an
127     *         empty collection or {@code null} if there are no active sessions.
128     */
129    Collection<Session> getActiveSessions();
130}