001package org.apache.turbine.pipeline;
002
003
004/*
005 * Licensed to the Apache Software Foundation (ASF) under one
006 * or more contributor license agreements.  See the NOTICE file
007 * distributed with this work for additional information
008 * regarding copyright ownership.  The ASF licenses this file
009 * to you under the Apache License, Version 2.0 (the
010 * "License"); you may not use this file except in compliance
011 * with the License.  You may obtain a copy of the License at
012 *
013 *   http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing,
016 * software distributed under the License is distributed on an
017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
018 * KIND, either express or implied.  See the License for the
019 * specific language governing permissions and limitations
020 * under the License.
021 */
022
023
024import java.io.IOException;
025
026import org.apache.turbine.TurbineConstants;
027import org.apache.turbine.annotation.TurbineConfiguration;
028import org.apache.turbine.annotation.TurbineLoader;
029import org.apache.turbine.annotation.TurbineService;
030import org.apache.turbine.modules.Page;
031import org.apache.turbine.modules.PageLoader;
032import org.apache.turbine.services.template.TemplateService;
033import org.apache.turbine.util.TurbineException;
034
035/**
036 * Implements the Page Generation portion of the "Turbine classic"
037 * processing pipeline (from the Turbine 2.x series).
038 *
039 * @author <a href="mailto:epugh@opensourceConnections.com">Eric Pugh</a>
040 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
041 * @version $Id$
042 */
043public class ExecutePageValve
044    implements Valve
045{
046    /** Injected service instance */
047    @TurbineService
048    private TemplateService templateService;
049
050    /** Injected loader instance */
051    @TurbineLoader( Page.class )
052    private PageLoader pageLoader;
053
054    @TurbineConfiguration( TurbineConstants.PAGE_DEFAULT_KEY )
055    private String pageDefault = TurbineConstants.PAGE_DEFAULT_DEFAULT;
056
057    /**
058     * @see org.apache.turbine.pipeline.Valve#invoke(PipelineData, ValveContext)
059     */
060    @Override
061    public void invoke(PipelineData pipelineData, ValveContext context)
062        throws IOException, TurbineException
063    {
064        try
065        {
066            executePage(pipelineData);
067        }
068        catch (Exception e)
069        {
070            throw new TurbineException(e);
071        }
072
073        // Pass control to the next Valve in the Pipeline
074        context.invokeNext(pipelineData);
075    }
076
077    /**
078     * execute the page generation.
079     *
080     * @param pipelineData The run-time data.
081     *
082     * @throws Exception if the page execution fails
083     */
084    protected void executePage(PipelineData pipelineData)
085        throws Exception
086    {
087        // Start the execution phase. DefaultPage will execute the
088        // appropriate action as well as get the Layout from the
089        // Screen and then execute that. The Layout is then
090        // responsible for executing the Navigation and Screen
091        // modules.
092        //
093        // Note that by default, this cannot be overridden from
094        // parameters passed in via post/query data. This is for
095        // security purposes.  You should really never need more
096        // than just the default page.  If you do, add logic to
097        // DefaultPage to do what you want.
098
099        String defaultPage = (templateService == null)
100        ? null : templateService.getDefaultPageName(pipelineData);
101
102        if (defaultPage == null)
103        {
104            /*
105             * In this case none of the template services are running.
106             * The application may be using ECS for views, or a
107             * decendent of RawScreen is trying to produce output.
108             * If there is a 'page.default' property in the TR.props
109             * then use that, otherwise return DefaultPage which will
110             * handle ECS view scenarios and RawScreen scenarios. The
111             * app developer can still specify the 'page.default'
112             * if they wish but the DefaultPage should work in
113             * most cases.
114             */
115            defaultPage = pageDefault;
116        }
117
118        pageLoader.exec(pipelineData, defaultPage);
119    }
120}