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;
020
021/**
022 * A ValidatingSessionManager is a SessionManager that can proactively validate any or all sessions
023 * that may be expired.
024 *
025 * @since 0.1
026 */
027public interface ValidatingSessionManager extends SessionManager {
028
029    /**
030     * Performs session validation for all open/active sessions in the system (those that
031     * have not been stopped or expired), and validates each one.  If a session is
032     * found to be invalid (e.g. it has expired), it is updated and saved to the EIS.
033     * <p/>
034     * This method is necessary in order to handle orphaned sessions and is expected to be run at
035     * a regular interval, such as once an hour, once a day or once a week, etc.
036     * The &quot;best&quot; frequency to run this method is entirely dependent upon the application
037     * and would be based on factors such as performance, average number of active users, hours of
038     * least activity, and other things.
039     * <p/>
040     * Most enterprise applications use a request/response programming model.
041     * This is obvious in the case of web applications due to the HTTP protocol, but it is
042     * equally true of remote client applications making remote method invocations.  The server
043     * essentially sits idle and only &quot;works&quot; when responding to client requests and/or
044     * method invocations.  This type of model is particularly efficient since it means the
045     * security system only has to validate a session during those cases.  Such
046     * &quot;lazy&quot; behavior enables the system to lie stateless and/or idle and only incur
047     * overhead for session validation when necessary.
048     * <p/>
049     * However, if a client forgets to log-out, or in the event of a server failure, it is
050     * possible for sessions to be orphaned since no further requests would utilize that session.
051     * Because of these lower-probability cases, it might be required to regularly clean-up the sessions
052     * maintained by the system, especially if sessions are backed by a persistent data store.
053     * <p/>
054     * Even in applications that aren't primarily based on a request/response model,
055     * such as those that use enterprise asynchronous messaging (where data is pushed to
056     * a client without first receiving a client request), it is almost always acceptable to
057     * utilize this lazy approach and run this method at defined interval.
058     * <p/>
059     * Systems that want to proactively validate individual sessions may simply call the
060     * {@link #getSession(SessionKey) getSession(SessionKey)} method on any
061     * {@code ValidatingSessionManager} instance as that method is expected to
062     * validate the session before retrieving it.  Note that even with proactive calls to {@code getSession},
063     * this {@code validateSessions()} method should be invoked regularly anyway to <em>guarantee</em> no
064     * orphans exist.
065     * <p/>
066     * <b>Note:</b> Shiro supports automatic execution of this method at a regular interval
067     * by using {@link SessionValidationScheduler}s.  The Shiro default SecurityManager implementations
068     * needing session validation will create and use one by default if one is not provided by the
069     * application configuration.
070     */
071    void validateSessions();
072}