/*
 * 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 jakarta.servlet;

import java.util.EventListener;

/**
 * A ServletRequestAttributeListener can be implemented by the developer interested in being notified of request
 * attribute changes. Notifications will be generated while the request is within the scope of the web application in
 * which the listener is registered. A request is defined as coming into scope when it is about to enter the first
 * servlet or filter in each web application, as going out of scope when it exits the last servlet or the first filter
 * in the chain.
 *
 * @since Servlet 2.4
 */
public interface ServletRequestAttributeListener extends EventListener {
    /**
     * Notification that a new attribute was added to the servlet request. Called after the attribute is added. The
     * default implementation is a NO-OP.
     *
     * @param srae Information about the new request attribute
     */
    default void attributeAdded(ServletRequestAttributeEvent srae) {
    }

    /**
     * Notification that an existing attribute has been removed from the servlet request. Called after the attribute is
     * removed. The default implementation is a NO-OP.
     *
     * @param srae Information about the removed request attribute
     */
    default void attributeRemoved(ServletRequestAttributeEvent srae) {
    }

    /**
     * Notification that an attribute was replaced on the servlet request. Called after the attribute is replaced. The
     * default implementation is a NO-OP.
     *
     * @param srae Information about the replaced request attribute
     */
    default void attributeReplaced(ServletRequestAttributeEvent srae) {
    }
}

