001    // Copyright 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.error;
016    
017    import org.apache.tapestry.IRequestCycle;
018    
019    /**
020     * Invoked by the {@link org.apache.tapestry.IEngine} if there's an uncaught
021     * exception (checked or runtime) processing a request. The ExceptionPresenter
022     * is responsible for presenting a exception message (or description) to the
023     * user. The default implementation activates the "Exception" page, but it is
024     * common to override this to do something application specific (typically,
025     * return to the Home page and display an error message there). This service
026     * also provides a good hook for creating a server-side log of exceptions.
027     * 
028     * @author Howard M. Lewis Ship
029     * @since 4.0
030     * @see RequestExceptionReporter
031     */
032    public interface ExceptionPresenter
033    {
034    
035        /**
036         * Report the exception and provide some response to the user in lieu of the
037         * expected result page.
038         * 
039         * @param cycle
040         *            the current request cycle
041         * @param cause
042         *            the exception that was caught
043         */
044    
045        void presentException(IRequestCycle cycle, Throwable cause);
046    }