/*
 * Copyright (c) 1997, 2023 Oracle and/or its affiliates and others.
 * 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 jakarta.servlet.http;

import java.util.EventListener;

/**
 * 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 jakarta.servlet.annotation.WebListener}, or registered via
 * one of the addListener methods defined on {@link jakarta.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.
     *
     * @implSpec The default implementation takes no action.
     *
     * @param se the HttpSessionEvent containing the session
     */
    default void sessionCreated(HttpSessionEvent se) {
    }

    /**
     * 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 void sessionDestroyed(HttpSessionEvent se) {
    }
}
