001// Copyright 200-2014 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
015package org.apache.tapestry5.services;
016
017import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
018
019import 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 *
031 * @param <T>
032 */
033@UsesMappedConfiguration(key = Class.class, value = ComponentEventResultProcessor.class)
034public interface ComponentEventResultProcessor<T>
035{
036    /**
037     * For a given, non-null return value from a component event method, construct and send a response.
038     * <p/>
039     * Starting in release 5.4, it is recommended that for any response that involves Tapestry pages or components,
040     * the implementation should create an {@link org.apache.tapestry5.ioc.IOOperation} to do the rendering, and
041     * add the operation to the {@link org.apache.tapestry5.services.Request} as attribute
042     * {@link org.apache.tapestry5.TapestryConstants#RESPONSE_RENDERER}.
043     * This avoids a number of issues related to the {@link org.apache.tapestry5.services.Environment}.
044     *
045     * @param value
046     *         the value returned from a method
047     * @throws RuntimeException
048     *         if the value can not handled
049     */
050    void processResultValue(T value) throws IOException;
051}