001// Copyright 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.internal.services;
016
017import org.apache.tapestry5.TapestryConstants;
018import org.apache.tapestry5.beanmodel.services.*;
019import org.apache.tapestry5.http.services.Request;
020import org.apache.tapestry5.ioc.IOOperation;
021import org.apache.tapestry5.ioc.OperationTracker;
022import org.apache.tapestry5.services.ComponentEventRequestParameters;
023import org.apache.tapestry5.services.ComponentRequestFilter;
024import org.apache.tapestry5.services.ComponentRequestHandler;
025import org.apache.tapestry5.services.PageRenderRequestParameters;
026
027import java.io.IOException;
028
029/**
030 * After processing the component event request (including Ajax requests), or the page render request,
031 * checks for the {@link org.apache.tapestry5.TapestryConstants#RESPONSE_RENDERER} request attribute,
032 * and invokes it to render the deferred response.
033 *
034 * @since 5.4
035 */
036public class DeferredResponseRenderer implements ComponentRequestFilter
037{
038    private final Request request;
039
040    private final OperationTracker tracker;
041
042    public DeferredResponseRenderer(Request request, OperationTracker tracker)
043    {
044        this.request = request;
045        this.tracker = tracker;
046    }
047
048    public void handleComponentEvent(ComponentEventRequestParameters parameters, ComponentRequestHandler handler) throws IOException
049    {
050        handler.handleComponentEvent(parameters);
051
052        invokeQueuedRenderer();
053    }
054
055    public void handlePageRender(PageRenderRequestParameters parameters, ComponentRequestHandler handler) throws IOException
056    {
057        handler.handlePageRender(parameters);
058
059        invokeQueuedRenderer();
060    }
061
062    private void invokeQueuedRenderer() throws IOException
063    {
064        while (true)
065        {
066
067            IOOperation responseRenderer = (IOOperation) request.getAttribute(TapestryConstants.RESPONSE_RENDERER);
068
069            if (responseRenderer == null)
070            {
071                break;
072            }
073
074            // There's a particular case where an operation puts a different operation into the attribute;
075            // we'll handle that on the next pass.
076            request.setAttribute(TapestryConstants.RESPONSE_RENDERER, null);
077
078            tracker.perform("Executing deferred response renderer.", responseRenderer);
079        }
080    }
081}