    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.services;
    014
    015import org.apache.tapestry5.ioc.annotations.UsesMappedConfiguration;
    016
    017import java.io.IOException;
    018
    019/**
    020 * Responsible for handling the return value provided by a component event handler method.
    021 *
    022 * There are two services built into Tapestry that implement this interface: ComponentEventResultProcessor (used for
    023 * ordinary page-oriented requests, and distinguished by the @{@link org.apache.tapestry5.services.Traditional}
    024 * and/or @{@link org.apache.tapestry5.ioc.annotations.Primary} marker annotations) and
    025 * AjaxComponentEventResultProcessor, used
    026 * for Ajax requests (which typically return a partially rendered page), distinguished by the @{@link
    027 * org.apache.tapestry5.services.Ajax} marker annotation.
    028 *
    029 * @param <T> the type of the values being handled
    030 */
    031@UsesMappedConfiguration(key = Class.class, value = ComponentEventResultProcessor.class)
    032public interface ComponentEventResultProcessor<T>
    033{
    034    /**
    035     * For a given, non-null return value from a component event method, construct and send a response.
    036     *
    037     * Starting in release 5.4, it is recommended that for any response that involves Tapestry pages or components,
    038     * the implementation should create an {@link org.apache.tapestry5.ioc.IOOperation} to do the rendering, and
    039     * add the operation to the {@link org.apache.tapestry5.http.services.Request} as attribute
    040     * {@link org.apache.tapestry5.TapestryConstants#RESPONSE_RENDERER}.
    041     * This avoids a number of issues related to the {@link org.apache.tapestry5.services.Environment}.
    042     *
    043     * @param value
    044     *         the value returned from a method
    045     * @throws RuntimeException
    046     *         if the value can not handled
    047     */
    048    void processResultValue(T value) throws IOException;
    049}