001    // Copyright 2006, 2008 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.tapestry5.services;
016    
017    import java.io.IOException;
018    
019    /**
020     * Service invoked when an uncaught exception occurs. The error handler is responsible for providing a response to the
021     * user to describe the error.
022     */
023    public interface RequestExceptionHandler
024    {
025        /**
026         * Reponsible for handling the error <em>in some way</em> and providing <em>some response</em> to the client. A
027         * default implementation may render an error response page.
028         * <p/>
029         * <p/>
030         * The handler is also responsible for setting the response status and the X-Tapestry-ErrorMessage response header.
031         * These are very important in Ajax requests to allow the client-side logic to detect the error and present it to
032         * the user.
033         *
034         * @param exception uncaught exception to be reported
035         * @throws IOException
036         */
037        void handleRequestException(Throwable exception) throws IOException;
038    }