001    // Copyright 2007, 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 org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
018    
019    import java.io.IOException;
020    
021    /**
022     * Responsible for handling the return value provided by a component event handler method.
023     * <p/>
024     * There are two services built into Tapestry that implement this interface: ComponentEventResultProcessor (used for
025     * ordinary page-oriented requests, and distinguished by the @{@link org.apache.tapestry5.services.Traditional}
026     * and/or @{@link org.apache.tapestry5.ioc.annotations.Primary} marker annotations) and 
027     * AjaxComponentEventResultProcessor, used
028     * for Ajax requests (which typically return a partially rendered page), distinguished by the @{@link
029     * org.apache.tapestry5.services.Ajax} marker annotation.
030     * @param <T>
031     */
032    @UsesMappedConfiguration(key = Class.class, value = ComponentEventResultProcessor.class)
033    public interface ComponentEventResultProcessor<T>
034    {
035        /**
036         * For a given, non-null return value from a component event method, construct and send a response.
037         *
038         * @param value the value returned from a method
039         * @throws RuntimeException if the value can not handled
040         */
041        void processResultValue(T value) throws IOException;
042    }