001 // Copyright 2005 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
015 package org.apache.tapestry.portlet;
016
017 import java.io.IOException;
018
019 import javax.portlet.PortletRequest;
020
021 import org.apache.tapestry.IRequestCycle;
022 import org.apache.tapestry.engine.IEngineService;
023 import org.apache.tapestry.engine.ILink;
024 import org.apache.tapestry.services.ServiceConstants;
025
026 /**
027 * Responsible for rendering out a page; a Portlet render URL is built during
028 * action processing that stores the active page; this is the page that will be
029 * rendered. The render service is (typically) the only service that operates
030 * during a portlet RenderRequest. All other services will be an ActionRequest
031 * that (via {@link org.apache.tapestry.portlet.PortletResponseRenderer},
032 * writes query parameters to activate this service during the render request.
033 * <p>
034 * Problematic is is anything related to the portlet mode or window state. As
035 * per the Portlet spec, when the user clicks the "help" or "edit" buttons (or
036 * the minimize, maximize, etc.), this causes a new RenderRequest, but
037 * explicitly keeps the render parameters set by the most recent ActionRequest.
038 * But what Tapestry needs is to detect that the mode or state has changed and
039 * select a different page to render the response. So we store the mode and
040 * state in effect when the ActionRequest executed as two more query parameters,
041 * and detect changes to mode and state that way. If there is a change, then we
042 * ignore the page query parameter and use the {@link PortletPageResolver} to
043 * figure out the correct page to display instead.
044 *
045 * @author Howard M. Lewis Ship
046 * @since 4.0
047 * @see org.apache.tapestry.services.impl.ResponseRendererImpl
048 */
049 public class RenderService implements IEngineService
050 {
051
052 private PortletRequest _request;
053
054 private PortletRenderer _portletRenderer;
055
056 private PortletPageResolver _pageResolver;
057
058 public ILink getLink(boolean post, Object parameter)
059 {
060 throw new UnsupportedOperationException(PortletMessages
061 .unsupportedMethod("getLink"));
062 }
063
064 public void service(IRequestCycle cycle)
065 throws IOException
066 {
067 String pageName = getPageNameToRender(cycle);
068
069 _portletRenderer.renderPage(cycle, pageName);
070 }
071
072 private String getPageNameToRender(IRequestCycle cycle)
073 {
074 if (isStateChange(cycle))
075 return _pageResolver.getPageNameForRequest(cycle);
076
077 return cycle.getParameter(ServiceConstants.PAGE);
078 }
079
080 /**
081 * Returns true if the portlet mode or the window state has changed since.
082 * The values stored previously (during an action request) are compared to
083 * the current values.
084 */
085
086 boolean isStateChange(IRequestCycle cycle)
087 {
088 String expectedPortletMode = cycle
089 .getParameter(PortletConstants.PORTLET_MODE);
090 String expectedWindowState = cycle
091 .getParameter(PortletConstants.WINDOW_STATE);
092
093 return !(_request.getPortletMode().toString().equals(
094 expectedPortletMode) && _request.getWindowState().toString()
095 .equals(expectedWindowState));
096
097 }
098
099 public String getName()
100 {
101 return PortletConstants.RENDER_SERVICE;
102 }
103
104 public void setPortletRenderer(PortletRenderer portletRenderer)
105 {
106 _portletRenderer = portletRenderer;
107 }
108
109 public void setRequest(PortletRequest request)
110 {
111 _request = request;
112 }
113
114 public void setPageResolver(PortletPageResolver pageResolver)
115 {
116 _pageResolver = pageResolver;
117 }
118 }