/*
 * 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 javax.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
 * @version $Rev$ $Date$
 */

public interface ServletRequestAttributeListener extends EventListener {
    /**
     * Notification that a new attribute was added to the
     * * servlet request. Called after the attribute is added.
     * @param srae event for attribute added
     */
    void attributeAdded(ServletRequestAttributeEvent srae);

    /**
     * Notification that an existing attribute has been removed from the
     * * servlet request. Called after the attribute is removed.
     * @param srae event for attribute removed
     */
    void attributeRemoved(ServletRequestAttributeEvent srae);

    /**
     * Notification that an attribute was replaced on the
     * * servlet request. Called after the attribute is replaced.
     * @param srae event for attribute replaced
     */
    void attributeReplaced(ServletRequestAttributeEvent srae);
}