001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.event;
016    
017    import java.util.EventListener;
018    
019    /**
020     * An interface for objects that want to take part in the validation of the
021     * page.
022     * 
023     * @author Mindbridge
024     * @since 3.0
025     */
026    
027    public interface PageValidateListener extends EventListener
028    {
029    
030        /**
031         * Invoked by the page from its
032         * {@link org.apache.tapestry.IPage#validate(org.apache.tapestry.IRequestCycle)}
033         * method.
034         * <p>
035         * May throw a {@link org.apache.tapestry.PageRedirectException}, to
036         * redirect the user to an appropriate part of the system (such as, a login
037         * page).
038         */
039    
040        void pageValidate(PageEvent event);
041    }