    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}