/*
 * $Header: /home/cvs/jakarta-tomcat-catalina/catalina/src/share/org/apache/catalina/Manager.java,v 1.7 2004/02/09 18:30:38 luehe Exp $
 * $Revision: 1.7 $
 * $Date: 2004/02/09 18:30:38 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
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 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */


package org.apache.catalina;


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


/**
 * A <b>Manager</b> manages the pool of Sessions that are associated with a
 * particular Container.  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.
 * <p>
 * In order for a <code>Manager</code> implementation to successfully operate
 * with a <code>Context</code> implementation that implements reloading, it
 * must obey the following constraints:
 * <ul>
 * <li>Must implement <code>Lifecycle</code> so that the Context can indicate
 *     that a restart is required.
 * <li>Must allow a call to <code>stop()</code> to be followed by a call to
 *     <code>start()</code> on the same <code>Manager</code> instance.
 * </ul>
 *
 * @author Craig R. McClanahan
 * @version $Revision: 1.7 $ $Date: 2004/02/09 18:30:38 $
 */

public interface Manager {


    // ------------------------------------------------------------- Properties


    /**
     * Return the Container with which this Manager is associated.
     */
    public Container getContainer();


    /**
     * Set the Container with which this Manager is associated.
     *
     * @param container The newly associated Container
     */
    public void setContainer(Container container);


    /**
     * Return the DefaultContext with which this Manager is associated.
     */
    public DefaultContext getDefaultContext();


    /**
     * Set the DefaultContext with which this Manager is associated.
     *
     * @param defaultContext The newly associated DefaultContext
     */
    public void setDefaultContext(DefaultContext defaultContext);


    /**
     * Return the distributable flag for the sessions supported by
     * this Manager.
     */
    public boolean getDistributable();


    /**
     * Set the distributable flag for the sessions supported by this
     * Manager.  If this flag is set, all user data objects added to
     * sessions associated with this manager must implement Serializable.
     *
     * @param distributable The new distributable flag
     */
    public void setDistributable(boolean distributable);


    /**
     * Return descriptive information about this Manager implementation and
     * the corresponding version number, in the format
     * <code>&lt;description&gt;/&lt;version&gt;</code>.
     */
    public String getInfo();


    /**
     * Return the default maximum inactive interval (in seconds)
     * for Sessions created by this Manager.
     */
    public int getMaxInactiveInterval();


    /**
     * Set the default maximum inactive interval (in seconds)
     * for Sessions created by this Manager.
     *
     * @param interval The new default value
     */
    public void setMaxInactiveInterval(int interval);


    /**
     * Gets the session id length (in bytes) of Sessions created by
     * this Manager.
     *
     * @return The session id length
     */
    public int getSessionIdLength();


    /**
     * Sets the session id length (in bytes) for Sessions created by this
     * Manager.
     *
     * @param sessionIdLength The session id length
     */
    public void setSessionIdLength(int idLength);


    // --------------------------------------------------------- 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);

    /**
     * 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.
     */                                                                         
    public Session createEmptySession();

    /**
     * Construct and return a new session object, based on the default
     * settings specified by this Manager's properties.  The session
     * id will be assigned by this method, and available via the getId()
     * method of the returned session.  If a new session cannot be created
     * for any reason, return <code>null</code>.
     *
     * @exception IllegalStateException if a new session cannot be
     *  instantiated for any reason
     */
    public Session createSession();


    /**
     * Return the active Session, associated with this Manager, with the
     * specified session id (if any); otherwise return <code>null</code>.
     *
     * @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
     */
    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.
     */
    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 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();



}
