    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    }