/*
 * Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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 javax.servlet.http;

import java.util.EventListener;

Interface for receiving notification events about HttpSession
lifecycle changes.
In order to receive these notification events, the implementation class must be either declared in the deployment descriptor of the web application, annotated with WebListener, or registered via one of the addListener methods defined on ServletContext. 
Implementations of this interface are invoked at their sessionCreated method in the order in which they have been declared, and at their sessionDestroyed method in reverse order. 
See Also:
HttpSessionEvent
Since:
Servlet 2.3/** 
 * Interface for receiving notification events about HttpSession
 * lifecycle changes.
 *
 * <p>In order to receive these notification events, the implementation
 * class must be either declared in the deployment descriptor of the web
 * application, annotated with {@link javax.servlet.annotation.WebListener},
 * or registered via one of the addListener methods defined on
 * {@link javax.servlet.ServletContext}.
 *
 * <p>Implementations of this interface are invoked at their
 * {@link #sessionCreated} method in the order in which they have been
 * declared, and at their {@link #sessionDestroyed} method in reverse
 * order.
 *
 * @see HttpSessionEvent
 *
 * @since Servlet 2.3
 */
public interface HttpSessionListener extends EventListener {
    
    
Receives notification that a session has been created.
Params:
se – the HttpSessionEvent containing the session
Implementation Requirements:

The default implementation takes no action./** 
     * Receives notification that a session has been created.
     *
     * @implSpec
     * The default implementation takes no action.
     *
     * @param se the HttpSessionEvent containing the session
     */
    default public void sessionCreated(HttpSessionEvent se) {}
    
    
Receives notification that a session is about to be invalidated.
Params:
se – the HttpSessionEvent containing the session
Implementation Requirements:

The default implementation takes no action./** 
     * Receives notification that a session is about to be invalidated.
     *
     * @implSpec
     * The default implementation takes no action.
     *
     * @param se the HttpSessionEvent containing the session
     */
    default public void sessionDestroyed(HttpSessionEvent se) {}
}