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/*
 * 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.catalina;

import java.beans.PropertyChangeListener;
import java.io.IOException;

/**
 * A Manager manages the pool of Sessions that are associated with a
 * particular Context. Different Manager implementations may support
 * value-added features such as the persistent storage of session data,
 * as well as migrating sessions for distributable web applications.
 * 

* In order for a Manager implementation to successfully operate * with a Context implementation that implements reloading, it * must obey the following constraints: *

    *
  • Must implement Lifecycle so that the Context can indicate * that a restart is required. *
  • Must allow a call to stop() to be followed by a call to * start() on the same Manager instance. *
* * @author Craig R. McClanahan */ public interface Manager { // ------------------------------------------------------------- Properties /** * Get the Context with which this Manager is associated. * * @return The associated Context */ public Context getContext(); /** * Set the Context with which this Manager is associated. The Context must * be set to a non-null value before the Manager is first used. Multiple * calls to this method before first use are permitted. Once the Manager has * been used, this method may not be used to change the Context (including * setting a {@code null} value) that the Manager is associated with. * * @param context The newly associated Context */ public void setContext(Context context); /** * @return the session id generator */ public SessionIdGenerator getSessionIdGenerator(); /** * Sets the session id generator * * @param sessionIdGenerator The session id generator */ public void setSessionIdGenerator(SessionIdGenerator sessionIdGenerator); /** * Returns the total number of sessions created by this manager. * * @return Total number of sessions created by this manager. */ public long getSessionCounter(); /** * Sets the total number of sessions created by this manager. * * @param sessionCounter Total number of sessions created by this manager. */ public void setSessionCounter(long sessionCounter); /** * Gets the maximum number of sessions that have been active at the same * time. * * @return Maximum number of sessions that have been active at the same * time */ public int getMaxActive(); /** * (Re)sets the maximum number of sessions that have been active at the * same time. * * @param maxActive Maximum number of sessions that have been active at * the same time. */ public void setMaxActive(int maxActive); /** * Gets the number of currently active sessions. * * @return Number of currently active sessions */ public int getActiveSessions(); /** * Gets the number of sessions that have expired. * * @return Number of sessions that have expired */ public long getExpiredSessions(); /** * Sets the number of sessions that have expired. * * @param expiredSessions Number of sessions that have expired */ public void setExpiredSessions(long expiredSessions); /** * Gets the number of sessions that were not created because the maximum * number of active sessions was reached. * * @return Number of rejected sessions */ public int getRejectedSessions(); /** * Gets the longest time (in seconds) that an expired session had been * alive. * * @return Longest time (in seconds) that an expired session had been * alive. */ public int getSessionMaxAliveTime(); /** * Sets the longest time (in seconds) that an expired session had been * alive. * * @param sessionMaxAliveTime Longest time (in seconds) that an expired * session had been alive. */ public void setSessionMaxAliveTime(int sessionMaxAliveTime); /** * Gets the average time (in seconds) that expired sessions had been * alive. This may be based on sample data. * * @return Average time (in seconds) that expired sessions had been * alive. */ public int getSessionAverageAliveTime(); /** * Gets the current rate of session creation (in session per minute). This * may be based on sample data. * * @return The current rate (in sessions per minute) of session creation */ public int getSessionCreateRate(); /** * Gets the current rate of session expiration (in session per minute). This * may be based on sample data * * @return The current rate (in sessions per minute) of session expiration */ public int getSessionExpireRate(); // --------------------------------------------------------- Public Methods /** * Add this Session to the set of active Sessions for this Manager. * * @param session Session to be added */ public void add(Session session); /** * Add a property change listener to this component. * * @param listener The listener to add */ public void addPropertyChangeListener(PropertyChangeListener listener); /** * Change the session ID of the current session to a new randomly generated * session ID. * * @param session The session to change the session ID for */ public void changeSessionId(Session session); /** * Change the session ID of the current session to a specified session ID. * * @param session The session to change the session ID for * @param newId new session ID */ public void changeSessionId(Session session, String newId); /** * Get a session from the recycled ones or create a new empty one. * The PersistentManager manager does not need to create session data * because it reads it from the Store. * * @return An empty Session object */ public Session createEmptySession(); /** * Construct and return a new session object, based on the default * settings specified by this Manager's properties. The session * id specified will be used as the session id. * If a new session cannot be created for any reason, return * null. * * @param sessionId The session id which should be used to create the * new session; if null, the session * id will be assigned by this method, and available via the getId() * method of the returned session. * @exception IllegalStateException if a new session cannot be * instantiated for any reason * * @return An empty Session object with the given ID or a newly created * session ID if none was specified */ public Session createSession(String sessionId); /** * Return the active Session, associated with this Manager, with the * specified session id (if any); otherwise return null. * * @param id The session id for the session to be returned * * @exception IllegalStateException if a new session cannot be * instantiated for any reason * @exception IOException if an input/output error occurs while * processing this request * * @return the request session or {@code null} if a session with the * requested ID could not be found */ public Session findSession(String id) throws IOException; /** * Return the set of active Sessions associated with this Manager. * If this Manager has no active Sessions, a zero-length array is returned. * * @return All the currently active sessions managed by this manager */ public Session[] findSessions(); /** * Load any currently active sessions that were previously unloaded * to the appropriate persistence mechanism, if any. If persistence is not * supported, this method returns without doing anything. * * @exception ClassNotFoundException if a serialized class cannot be * found during the reload * @exception IOException if an input/output error occurs */ public void load() throws ClassNotFoundException, IOException; /** * Remove this Session from the active Sessions for this Manager. * * @param session Session to be removed */ public void remove(Session session); /** * Remove this Session from the active Sessions for this Manager. * * @param session Session to be removed * @param update Should the expiration statistics be updated */ public void remove(Session session, boolean update); /** * Remove a property change listener from this component. * * @param listener The listener to remove */ public void removePropertyChangeListener(PropertyChangeListener listener); /** * Save any currently active sessions in the appropriate persistence * mechanism, if any. If persistence is not supported, this method * returns without doing anything. * * @exception IOException if an input/output error occurs */ public void unload() throws IOException; /** * This method will be invoked by the context/container on a periodic * basis and allows the manager to implement * a method that executes periodic tasks, such as expiring sessions etc. */ public void backgroundProcess(); /** * Would the Manager distribute the given session attribute? Manager * implementations may provide additional configuration options to control * which attributes are distributable. * * @param name The attribute name * @param value The attribute value * * @return {@code true} if the Manager would distribute the given attribute * otherwise {@code false} */ public boolean willAttributeDistribute(String name, Object value); }




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