trinidad-impl/src/main/java/org/apache/myfaces/trinidadinternal/renderkit/core/ppr/PPRResponseWriter.java - myfaces-trinidad - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */
 package org.apache.myfaces.trinidadinternal.renderkit.core.ppr;


 import java.io.IOException;
 import java.io.Writer;

 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;

 import javax.faces.component.UIComponent;
 import javax.faces.context.ExternalContext;
 import javax.faces.context.FacesContext;
 import javax.faces.context.PartialResponseWriter;
 import javax.faces.context.ResponseWriter;

 import org.apache.myfaces.trinidad.context.PartialPageContext;
 import org.apache.myfaces.trinidad.context.RenderingContext;
 import org.apache.myfaces.trinidad.logging.TrinidadLogger;
 import org.apache.myfaces.trinidad.render.ExtendedRenderKitService;
 import org.apache.myfaces.trinidad.render.RenderUtils;
 import org.apache.myfaces.trinidad.util.Service;

 import org.apache.myfaces.trinidadinternal.io.ResponseWriterDecorator;
 import org.apache.myfaces.trinidadinternal.renderkit.core.pages.GenericEntry;
 import org.apache.myfaces.trinidadinternal.util.StateUtils;

 /**
  * Write out a PPR response in the following form:
  * <content action="http://new-action-url">
  *   <fragment><![CDATA[....html....]]></fragment>
  *   <fragment><![CDATA[....more html....]]></fragment
  * </content>
  *
  * TODO: write out fragments only once we've detected the
  * ID, to avoid sending unnecessary fragments
  */
 public class PPRResponseWriter extends ScriptBufferingResponseWriter
 {
   public PPRResponseWriter(ResponseWriter     out,
                            RenderingContext   rc,
                            boolean            bufferScripts)
   {
     super(out, bufferScripts);
     PartialPageContext pprContext = rc.getPartialPageContext();
     if (!(pprContext instanceof PartialPageContextImpl))
         throw new IllegalArgumentException();

     _state = new State((PartialPageContextImpl) pprContext);
     _xml        = new XmlResponseWriter(out, out.getCharacterEncoding());
     _bufferScripts = bufferScripts;
   }

   /**
    * Constructor for use when cloning.
    */
   PPRResponseWriter(ResponseWriter out,
                     PPRResponseWriter base)
   {
     super(out, base._bufferScripts);
     // New XmlResponseWriter
     _xml        = new XmlResponseWriter(out, out.getCharacterEncoding());
     // But the rest of the state is shared
     _state = base._state;
     _bufferScripts = base._bufferScripts;
   }


   public ResponseWriter cloneWithWriter(Writer writer)
   {
     PPRResponseWriter ppr = new PPRResponseWriter(
       getResponseWriter().cloneWithWriter(writer),
       this);

     // BIG HACK: The JSF 1.1
     // ViewTag is going to clone the ResponseWriter so that
     // it can write its BodyContent out.  But that'll clone a
     // PPRResponseWriter, which then will adamantly refuse to write
     // out any content!  To "fix" this, we make the lousy assumption
     // that if we're being cloned, and our element depth is zero,
     // then we're probably being used in this way, and we should just
     // let everything through.
     // HOWEVER, in Facelets, cloneWithWriter() is called eaaaaarly.
     // Catch that by ignoring this unless we've at least had a call
     // to startDocument()
     _state.forceInsideTarget = (_state.documentStarted &&
                                  (_state.elementDepth == 0));
     return ppr;
   }

   public void startDocument() throws IOException
   {
     // Mark that we've started the document, so cloneWithWriter()
     // can start activating "forceInsideTarget" correctly
     _state.documentStarted = true;

     // Mark that we're in the middle of starting the document,
     // so that _disableIfNeeded() can do its thing - see that
     // function for more info
     _state.documentStarting = true;

     // We force the encoding to be text/xml in XmlHttpServletResponse
     // because setContentType is ignored when inside an included page (bug 5591124)
     _xml.startDocument();

     // Stick another PI indicating that this is a rich reponse
     // Used for an Iframe based communication channel, since it cannot
     // read response headers
     // TODO: Do we need this?
     // _xml.write("<?Tr-XHR-Response-Type ?>\n");

     _xml.startElement(_ELEMENT_PARTIAL_RESPONSE, null);

     // TODO: Portlet support for PPR?
     // TODO: PS - Not sure why this extra space is being written out, but this causes an 'malformed
     // XML error to be thrown by JSF 2 Ajax. Commented out the line.
     // _xml.writeText(" ", null);

     _state.documentStarting = false;
   }

   public void endDocument() throws IOException
   {
     _writeFormActionScript();

     // Write out any buffered <script src=""> or inline scripts
     if (_bufferScripts)
       writeBufferedScripts();

     // Write out all of the framework-level scripts
     writeFrameworkScripts();

     _endChanges();
     _xml.endElement(_ELEMENT_PARTIAL_RESPONSE);
     _xml.endDocument();

     // Force "inside target mode" - this is for Facelets,
     // where the state is rendered after endDocument() is called
     _state.forceInsideTarget = true;
   }

   public void writeComment(Object text) throws IOException
   {
     if (_isInsideTarget())
       super.writeComment(text);
   }


   public void writeText(Object text, String property) throws IOException
   {
     if (_isInsideTarget())
       super.writeText(text, property);
   }

   public void writeText(
                         char[]      text,
                         int         start,
                         int         length) throws IOException
   {
     if (_isInsideTarget())
       super.writeText(text, start, length);
   }


   public void write(String text) throws IOException
   {
     _disableIfNeeded();
     if (_isInsideTarget())
       super.write(text);
   }

   public void write(
                     char[]      text,
                     int         start,
                     int         length) throws IOException
   {
     _disableIfNeeded();
     if (_isInsideTarget())
       super.write(text, start, length);
   }

   public void write(int ch) throws IOException
   {
     if (_isInsideTarget())
       super.write(ch);
   }

   @Override
   public void write(char[] c) throws IOException
   {
     _disableIfNeeded();
     if (_isInsideTarget())
       super.write(c);
   }

   @Override
   public void write(String text, int off, int len) throws IOException
   {
     _disableIfNeeded();
     if (_isInsideTarget())
       super.write(text, off, len);
   }

   @Override
   public void writeDoctype(String doctype) throws IOException {
     if (_isInsideTarget()) {
       super.writeDoctype(doctype);
     }
   }

   @Override
   public void writeText(Object      text,
                         UIComponent component,
                         String      propertyName) throws IOException
   {
     if (_isInsideTarget() && (text != null))
       super.writeText(text, component, propertyName);
   }

   public void startElement(String name, UIComponent component)
      throws IOException
   {
     _state.elementDepth++;
     _pushPartialTarget(component, name);

     if (_isInsideTarget())
     {
       if (_LOG.isFinest())
       {
         _LOG.finest("PPR: Using element {0} in component {1}",
                     new Object[]{name, component});
       }

       super.startElement(name, component);
     }
     else
     {
       if (_LOG.isFinest())
       {
         _LOG.finest("PPR: Ignoring element {0} in component {1}",
                     new Object[]{name, component});
       }
     }
   }


   public void endElement(String name) throws IOException
   {
     _state.elementDepth--;
     if (_isInsideTarget())
       super.endElement(name);

     _popPartialTarget(name);
     super.flush();
   }

   public void writeAttribute(String     name,
                              Object     value,
                              String     property) throws IOException
   {
     if (value == null)
       return;

     // Write out attributes when we're inside a target and outputting
     // normally
     if (_isInsideTarget())
     {
       _handleIdAttribute(name, value);

       super.writeAttribute(name, value, property);
     }
   }

   public void writeURIAttribute(
                                 String     name,
                                 Object     value,
                                 String     property) throws IOException
   {
     // Write out attributes when we're inside a target and outputting
     // normally
     if (_isInsideTarget())
     {
       // We actually use writeURIAttribute() to write out the "id"
       // of our links, because "name" is actually kind of a URI
       // property, and "id" is required to be the same as "name".
       // A strange decision that should be revisited, but for now,
       // trap writeURIAttribute() too
       _handleIdAttribute(name, value);

       super.writeURIAttribute(name, value, property);
     }
   }

   public void writeViewState(String state) throws IOException
   {
     _startChanges();
     _xml.startElement(_ELEMENT_CHANGES_UPDATE, null);
     //_xml.writeAttribute(_ATTRIBUTE_ID, PartialResponseWriter.VIEW_STATE_MARKER, null);
     _xml.writeAttribute(_ATTRIBUTE_ID, StateUtils.getViewStateId(FacesContext.getCurrentInstance()), null);
     _xml.startCDATA();
     _xml.write(state);
     _xml.endCDATA();
     _xml.endElement(_ELEMENT_CHANGES_UPDATE);
     _xml.flush();
   }

   /*
    * Allows subclasses to retrieve the underlying response writer and bypass PPR logic
    * allowing content to be written only by partial targets
    * @return underlying ResponseWriter
    */
   protected ResponseWriter getXmlResponseWriter()
   {
     return _xml;
   }

   /*
    * Writes out buffered inline scripts and script libraries
    */

   protected void writeBufferedScripts() throws IOException
   {
     List<String> libraries = getBufferedLibraries();
     if (libraries != null)
     {
       for (String library : libraries)
       {
         _xml.startElement(_ELEMENT_EXTENSION, null);
         _xml.writeAttribute(_ATTRIBUTE_ID, "tr-script-library", null);
         _xml.writeText(library, null);
         _xml.endElement(_ELEMENT_EXTENSION);
       }
     }

     List<String> scripts = getBufferedScripts();
     if (scripts != null)
     {
       for (String script : scripts)
       {
         _xml.startElement(_ELEMENT_EVAL, null);
         _xml.startCDATA();
         _xml.write(script);
         _xml.endCDATA();
         _xml.endElement(_ELEMENT_EVAL);
       }
     }

     // Clear out any buffered scripts/libraries
     clearBufferedContents();
   }

   /*
    * Writes out framework-level scripts
    */
   protected void writeFrameworkScripts() throws IOException
   {
     ResponseWriter old = _facesContext.getResponseWriter();

     // ExtendedRenderKitService will write out a <script> element.
     // We want to replace it with <eval> and surround the script with CDATA
     // All attributes will be ignored
     ResponseWriter xml = new ResponseWriterDecorator(_xml)
       {
         public void startElement(String name, UIComponent component) throws IOException
         {
           if ("script".equalsIgnoreCase(name))
           {
             _xml.startElement(_ELEMENT_EVAL, null);
           }
         }
         public void endElement(String name) throws IOException
         {
           if ("script".equalsIgnoreCase(name))
           {
             _xml.endElement(_ELEMENT_EVAL);
           }
         }
         public void writeAttribute(String name, Object value, String attrName) throws IOException
         {
         }
       };

     _facesContext.setResponseWriter(xml);
     try
     {
       // And also encode ExtendedRenderKitService scripts.  (ERKS
       // renders its own script wrapper element.)
       ExtendedRenderKitService erks =
         Service.getService(_facesContext.getRenderKit(),
                            ExtendedRenderKitService.class);
       if (erks != null)
         erks.encodeScripts(_facesContext);
     }
     finally
     {
       _facesContext.setResponseWriter(old);
     }
   }

   // We need to set form action URL by writing out a JS call because the response
   // may be processed by jsf.ajax
   private void _writeFormActionScript() throws IOException
   {
     String viewId = _facesContext.getViewRoot().getViewId();
     // HACK: don't write out an "action" for PPR on a GenericEntry page
     // (basically entirely for the InlineDatePicker case)
     if (!GenericEntry.getViewId().equals(viewId))
     {
       _xml.startElement(_ELEMENT_EVAL, null);
       _xml.startCDATA();


       StringBuilder script = new StringBuilder(128);
       script.append("TrPage.getInstance().__handlePprResponseAction('");

       String actionURL = _facesContext.getApplication().
         getViewHandler().getActionURL(_facesContext, viewId);
       ExternalContext external = _facesContext.getExternalContext();

       script.append(external.encodeActionURL(actionURL));
       script.append("');");

       _xml.write(script.toString());

       _xml.endCDATA();
       _xml.endElement(_ELEMENT_EVAL);
     }
   }

   private void _pushPartialTarget(
     UIComponent component,
     String      elementName)
     throws IOException
   {
     PPRTag tag = null;

     // If we're already inside a target, don't bother
     if (!_isInsideTarget())
     {
       if (component != null)
       {
         String clientId = component.getClientId(_facesContext);
         String renderedClientId = RenderUtils.getRendererClientId(_facesContext, component);
         if (_state.pprContext.isPartialTarget(clientId))
         {
           tag = new PPRTag(clientId, renderedClientId);
           _state.enteringPPR = component;
         }
       }
     }

     if (tag != null)
     {
       super.flush();
       tag.startUpdate(_state.pprContext, elementName);
     }

     _state.componentStack.add(tag);
   }

   private void _popPartialTarget(String elementName) throws IOException
   {
     List<PPRTag> componentStack = _state.componentStack;
     int pos = componentStack.size() - 1;
     PPRTag tag = componentStack.get(pos);
     componentStack.remove(pos);

     if (tag != null)
       tag.finishUpdate(_state.pprContext, elementName);
   }

   private boolean _isInsideTarget()
   {
     // Only use the real ResponseWriter when we are rendering
     // a partial target subtree.  Otherwise, we discard all
     // output.
     return _state.forceInsideTarget ||
            _state.pprContext.isInsidePartialTarget();
   }


   //
   // Facelets - as of version 1.1.11 - does something
   // very strange with its ResponseWriter stack.
   // It starts with an ordinary stack (which will have
   // a PPRResponseWriter around an HtmlResponseWriter).
   // Then it treats that *as an ordinary Writer*, and
   // wraps it in a "StateWriter" class, which merely
   // is used to switch between passing output through
   // and buffering it.  Then it takes that StateWriter
   // and uses it to cloneWithWriter() a new ResponseWriter
   // stack!  As a result, we have the following stack
   // outermost to innermost:
   //   PPRResponseWriter
   //   HtmlResponseWriter
   //   StateWriter
   //   PPRResponseWriter
   //   HtmlResponseWriter
   //   ServletResponse's Writer
   // In the end, we have to get that "inner" PPRResponseWriter
   // to just cut it out and pass everything through.  Hence,
   // this hack!  So If I get a "write" call while we're
   // inside of startDocument(), assume that I must be an
   // abused PPRResponseWriter, and just put myself in
   // pass-everything-through mode
   //
   private void _disableIfNeeded()
   {
     if (_state.documentStarting)
     {
       _state = new State(_state.pprContext);
       _state.forceInsideTarget = true;
     }
   }

   private void _handleIdAttribute(String name, Object value)
   {
     if ((_state.enteringPPR != null) && "id".equals(name))
     {
       if (_LOG.isFine())
       {
         _LOG.fine("Using id {1} for element of {0}",
                   new Object[]{_state.enteringPPR, value});
       }

       _state.pprContext.addRenderedPartialTarget(value.toString());
       _state.enteringPPR = null;
     }
   }

   private void _startChanges() throws IOException
   {
     if (!_state.changesStarted)
     {
       _xml.startElement(_ELEMENT_CHANGES, null);
       _state.changesStarted = true;
     }
   }

   private void _endChanges()
     throws IOException
   {
     if (_state.changesStarted)
     {
       _xml.endElement("changes");
       _state.changesStarted = false;
     }
   }

   @Override
   public void startCDATA()
     throws IOException
   {
     _xml.startCDATA();
   }

   @Override
   public void endCDATA()
     throws IOException
   {
     _xml.endCDATA();
   }

   //
   // Class representing PPR behavior associated with a tag.  The
   // base class simply tells PPR when it's working with a partial target
   //
   private class PPRTag
   {
     private PPRTag(String id, String renderedId)
     {
       _id = id;
       _renderedId = renderedId != null ? renderedId : id;
     }

     public void startUpdate(
       PartialPageContextImpl pprContext,
       String             elementName) throws IOException
     {
       if (_id != null)
       {
         _startChanges();
         pprContext.pushRenderedPartialTarget(_id);
         _xml.startElement(_ELEMENT_CHANGES_UPDATE, null);
         _xml.writeAttribute(_ATTRIBUTE_ID, _renderedId, null);
         _xml.startCDATA();
         _xml.flush(); // NEW

         if (_LOG.isFine())
         {
           _LOG.fine("Entering partial target id {0}", _id);
         }

         // Write out wrapper elements needed to ensure valid HTML
         _startWrapperElements(elementName);
       }
     }

     public void finishUpdate(
       PartialPageContextImpl pprContext,
       String             elementName) throws IOException
     {
       if (_id != null)
       {
         if (_state.enteringPPR != null)
         {
           _LOG.warning("NO_PPR_CAPABLE_ID_FOUND_FOR_COMPONENT",
                        _state.enteringPPR);
           _state.enteringPPR = null;
         }

         // Close up wrapper elements needed to ensure valid HTML
         _endWrapperElements(elementName);

         PPRResponseWriter.super.flush();

         _xml.endCDATA();
         _xml.endElement(_ELEMENT_CHANGES_UPDATE);
         _xml.flush();

         pprContext.popRenderedPartialTarget();
         _LOG.finer("Leaving partial target id {0}", _id);
       }
     }

     // Write out wrapper elements needed to generate valid HTML content
     private void _startWrapperElements(String elementName) throws IOException
     {
       // If the partial target has <tr>/<td> as its root element, we
       // need to wrap these contents such that the root element is
       // a <table>.  This allows us to shove this content into a
       // div as innerHTML on the client to produce the DOM tree.  Without
       // this, the resulting HTML is invalid and the DOM tree is not
       // produced.
       boolean isTR = "tr".equalsIgnoreCase(elementName);
       boolean isTD = "td".equalsIgnoreCase(elementName);

       if (isTR || isTD)
       {
         PPRResponseWriter.super.startElement("table", null);

         if (isTD)
           PPRResponseWriter.super.startElement("tr", null);
       }
     }

     // Close up wrapper elements needed to generate valid HTML content
     private void _endWrapperElements(String elementName) throws IOException
     {
       // Close up <table>/<tr> tags if necessary.
       boolean isTR = "tr".equalsIgnoreCase(elementName);
       boolean isTD = "td".equalsIgnoreCase(elementName);
       if (isTR || isTD)
       {
         if (isTD)
           PPRResponseWriter.super.endElement("tr");

         PPRResponseWriter.super.endElement("table");
       }
     }

     private String _id;
     private String _renderedId;
   }


   static private class State
   {
     public State(PartialPageContextImpl pprContext)
     {
       this.pprContext = pprContext;
     }

     public UIComponent    enteringPPR;
     public boolean       forceInsideTarget;
     public int           elementDepth;
     public boolean       documentStarted;
     public boolean       documentStarting;
     public boolean       changesStarted;
     public final List<PPRTag> componentStack = new ArrayList<PPRTag>(50);
     public final PartialPageContextImpl pprContext;
   }

   private State _state;
   private ResponseWriter _xml;
   private boolean _bufferScripts;
   private final FacesContext _facesContext = FacesContext.getCurrentInstance();

   static private final TrinidadLogger _LOG = TrinidadLogger.createTrinidadLogger(PPRResponseWriter.class);
   private static final String _ELEMENT_PARTIAL_RESPONSE = "partial-response";
   private static final String _ELEMENT_CHANGES = "changes";
   private static final String _ELEMENT_CHANGES_UPDATE = "update";
   private static final String _ELEMENT_EVAL = "eval";
   private static final String _ELEMENT_EXTENSION = "extension";
   private static final String _ATTRIBUTE_ID = "id";
   private static final List<String> _allowedIds = Arrays.asList(PartialResponseWriter.VIEW_STATE_MARKER);

 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/
	package org.apache.myfaces.trinidadinternal.renderkit.core.ppr;


	import java.io.IOException;
	import java.io.Writer;

	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.List;

	import javax.faces.component.UIComponent;
	import javax.faces.context.ExternalContext;
	import javax.faces.context.FacesContext;
	import javax.faces.context.PartialResponseWriter;
	import javax.faces.context.ResponseWriter;

	import org.apache.myfaces.trinidad.context.PartialPageContext;
	import org.apache.myfaces.trinidad.context.RenderingContext;
	import org.apache.myfaces.trinidad.logging.TrinidadLogger;
	import org.apache.myfaces.trinidad.render.ExtendedRenderKitService;
	import org.apache.myfaces.trinidad.render.RenderUtils;
	import org.apache.myfaces.trinidad.util.Service;

	import org.apache.myfaces.trinidadinternal.io.ResponseWriterDecorator;
	import org.apache.myfaces.trinidadinternal.renderkit.core.pages.GenericEntry;
	import org.apache.myfaces.trinidadinternal.util.StateUtils;

	/**
	* Write out a PPR response in the following form:
	* <content action="http://new-action-url">
	* <fragment><![CDATA[....html....]]></fragment>
	* <fragment><![CDATA[....more html....]]></fragment
	* </content>
	*
	* TODO: write out fragments only once we've detected the
	* ID, to avoid sending unnecessary fragments
	*/
	public class PPRResponseWriter extends ScriptBufferingResponseWriter
	{
	public PPRResponseWriter(ResponseWriter out,
	RenderingContext rc,
	boolean bufferScripts)
	{
	super(out, bufferScripts);
	PartialPageContext pprContext = rc.getPartialPageContext();
	if (!(pprContext instanceof PartialPageContextImpl))
	throw new IllegalArgumentException();

	_state = new State((PartialPageContextImpl) pprContext);
	_xml = new XmlResponseWriter(out, out.getCharacterEncoding());
	_bufferScripts = bufferScripts;
	}

	/**
	* Constructor for use when cloning.
	*/
	PPRResponseWriter(ResponseWriter out,
	PPRResponseWriter base)
	{
	super(out, base._bufferScripts);
	// New XmlResponseWriter
	_xml = new XmlResponseWriter(out, out.getCharacterEncoding());
	// But the rest of the state is shared
	_state = base._state;
	_bufferScripts = base._bufferScripts;
	}


	public ResponseWriter cloneWithWriter(Writer writer)
	{
	PPRResponseWriter ppr = new PPRResponseWriter(
	getResponseWriter().cloneWithWriter(writer),
	this);

	// BIG HACK: The JSF 1.1
	// ViewTag is going to clone the ResponseWriter so that
	// it can write its BodyContent out. But that'll clone a
	// PPRResponseWriter, which then will adamantly refuse to write
	// out any content! To "fix" this, we make the lousy assumption
	// that if we're being cloned, and our element depth is zero,
	// then we're probably being used in this way, and we should just
	// let everything through.
	// HOWEVER, in Facelets, cloneWithWriter() is called eaaaaarly.
	// Catch that by ignoring this unless we've at least had a call
	// to startDocument()
	_state.forceInsideTarget = (_state.documentStarted &&
	(_state.elementDepth == 0));
	return ppr;
	}

	public void startDocument() throws IOException
	{
	// Mark that we've started the document, so cloneWithWriter()
	// can start activating "forceInsideTarget" correctly
	_state.documentStarted = true;

	// Mark that we're in the middle of starting the document,
	// so that _disableIfNeeded() can do its thing - see that
	// function for more info
	_state.documentStarting = true;

	// We force the encoding to be text/xml in XmlHttpServletResponse
	// because setContentType is ignored when inside an included page (bug 5591124)
	_xml.startDocument();

	// Stick another PI indicating that this is a rich reponse
	// Used for an Iframe based communication channel, since it cannot
	// read response headers
	// TODO: Do we need this?
	// _xml.write("<?Tr-XHR-Response-Type ?>\n");

	_xml.startElement(_ELEMENT_PARTIAL_RESPONSE, null);

	// TODO: Portlet support for PPR?
	// TODO: PS - Not sure why this extra space is being written out, but this causes an 'malformed
	// XML error to be thrown by JSF 2 Ajax. Commented out the line.
	// _xml.writeText(" ", null);

	_state.documentStarting = false;
	}

	public void endDocument() throws IOException
	{
	_writeFormActionScript();

	// Write out any buffered <script src=""> or inline scripts
	if (_bufferScripts)
	writeBufferedScripts();

	// Write out all of the framework-level scripts
	writeFrameworkScripts();

	_endChanges();
	_xml.endElement(_ELEMENT_PARTIAL_RESPONSE);
	_xml.endDocument();

	// Force "inside target mode" - this is for Facelets,
	// where the state is rendered after endDocument() is called
	_state.forceInsideTarget = true;
	}

	public void writeComment(Object text) throws IOException
	{
	if (_isInsideTarget())
	super.writeComment(text);
	}


	public void writeText(Object text, String property) throws IOException
	{
	if (_isInsideTarget())
	super.writeText(text, property);
	}

	public void writeText(
	char[] text,
	int start,
	int length) throws IOException
	{
	if (_isInsideTarget())
	super.writeText(text, start, length);
	}


	public void write(String text) throws IOException
	{
	_disableIfNeeded();
	if (_isInsideTarget())
	super.write(text);
	}

	public void write(
	char[] text,
	int start,
	int length) throws IOException
	{
	_disableIfNeeded();
	if (_isInsideTarget())
	super.write(text, start, length);
	}

	public void write(int ch) throws IOException
	{
	if (_isInsideTarget())
	super.write(ch);
	}

	@Override
	public void write(char[] c) throws IOException
	{
	_disableIfNeeded();
	if (_isInsideTarget())
	super.write(c);
	}

	@Override
	public void write(String text, int off, int len) throws IOException
	{
	_disableIfNeeded();
	if (_isInsideTarget())
	super.write(text, off, len);
	}

	@Override
	public void writeDoctype(String doctype) throws IOException {
	if (_isInsideTarget()) {
	super.writeDoctype(doctype);
	}
	}

	@Override
	public void writeText(Object text,
	UIComponent component,
	String propertyName) throws IOException
	{
	if (_isInsideTarget() && (text != null))
	super.writeText(text, component, propertyName);
	}

	public void startElement(String name, UIComponent component)
	throws IOException
	{
	_state.elementDepth++;
	_pushPartialTarget(component, name);

	if (_isInsideTarget())
	{
	if (_LOG.isFinest())
	{
	_LOG.finest("PPR: Using element {0} in component {1}",
	new Object[]{name, component});
	}

	super.startElement(name, component);
	}
	else
	{
	if (_LOG.isFinest())
	{
	_LOG.finest("PPR: Ignoring element {0} in component {1}",
	new Object[]{name, component});
	}
	}
	}


	public void endElement(String name) throws IOException
	{
	_state.elementDepth--;
	if (_isInsideTarget())
	super.endElement(name);

	_popPartialTarget(name);
	super.flush();
	}

	public void writeAttribute(String name,
	Object value,
	String property) throws IOException
	{
	if (value == null)
	return;

	// Write out attributes when we're inside a target and outputting
	// normally
	if (_isInsideTarget())
	{
	_handleIdAttribute(name, value);

	super.writeAttribute(name, value, property);
	}
	}

	public void writeURIAttribute(
	String name,
	Object value,
	String property) throws IOException
	{
	// Write out attributes when we're inside a target and outputting
	// normally
	if (_isInsideTarget())
	{
	// We actually use writeURIAttribute() to write out the "id"
	// of our links, because "name" is actually kind of a URI
	// property, and "id" is required to be the same as "name".
	// A strange decision that should be revisited, but for now,
	// trap writeURIAttribute() too
	_handleIdAttribute(name, value);

	super.writeURIAttribute(name, value, property);
	}
	}

	public void writeViewState(String state) throws IOException
	{
	_startChanges();
	_xml.startElement(_ELEMENT_CHANGES_UPDATE, null);
	//_xml.writeAttribute(_ATTRIBUTE_ID, PartialResponseWriter.VIEW_STATE_MARKER, null);
	_xml.writeAttribute(_ATTRIBUTE_ID, StateUtils.getViewStateId(FacesContext.getCurrentInstance()), null);
	_xml.startCDATA();
	_xml.write(state);
	_xml.endCDATA();
	_xml.endElement(_ELEMENT_CHANGES_UPDATE);
	_xml.flush();
	}

	/*
	* Allows subclasses to retrieve the underlying response writer and bypass PPR logic
	* allowing content to be written only by partial targets
	* @return underlying ResponseWriter
	*/
	protected ResponseWriter getXmlResponseWriter()
	{
	return _xml;
	}

	/*
	* Writes out buffered inline scripts and script libraries
	*/

	protected void writeBufferedScripts() throws IOException
	{
	List<String> libraries = getBufferedLibraries();
	if (libraries != null)
	{
	for (String library : libraries)
	{
	_xml.startElement(_ELEMENT_EXTENSION, null);
	_xml.writeAttribute(_ATTRIBUTE_ID, "tr-script-library", null);
	_xml.writeText(library, null);
	_xml.endElement(_ELEMENT_EXTENSION);
	}
	}

	List<String> scripts = getBufferedScripts();
	if (scripts != null)
	{
	for (String script : scripts)
	{
	_xml.startElement(_ELEMENT_EVAL, null);
	_xml.startCDATA();
	_xml.write(script);
	_xml.endCDATA();
	_xml.endElement(_ELEMENT_EVAL);
	}
	}

	// Clear out any buffered scripts/libraries
	clearBufferedContents();
	}

	/*
	* Writes out framework-level scripts
	*/
	protected void writeFrameworkScripts() throws IOException
	{
	ResponseWriter old = _facesContext.getResponseWriter();

	// ExtendedRenderKitService will write out a <script> element.
	// We want to replace it with <eval> and surround the script with CDATA
	// All attributes will be ignored
	ResponseWriter xml = new ResponseWriterDecorator(_xml)
	{
	public void startElement(String name, UIComponent component) throws IOException
	{
	if ("script".equalsIgnoreCase(name))
	{
	_xml.startElement(_ELEMENT_EVAL, null);
	}
	}
	public void endElement(String name) throws IOException
	{
	if ("script".equalsIgnoreCase(name))
	{
	_xml.endElement(_ELEMENT_EVAL);
	}
	}
	public void writeAttribute(String name, Object value, String attrName) throws IOException
	{
	}
	};

	_facesContext.setResponseWriter(xml);
	try
	{
	// And also encode ExtendedRenderKitService scripts. (ERKS
	// renders its own script wrapper element.)
	ExtendedRenderKitService erks =
	Service.getService(_facesContext.getRenderKit(),
	ExtendedRenderKitService.class);
	if (erks != null)
	erks.encodeScripts(_facesContext);
	}
	finally
	{
	_facesContext.setResponseWriter(old);
	}
	}

	// We need to set form action URL by writing out a JS call because the response
	// may be processed by jsf.ajax
	private void _writeFormActionScript() throws IOException
	{
	String viewId = _facesContext.getViewRoot().getViewId();
	// HACK: don't write out an "action" for PPR on a GenericEntry page
	// (basically entirely for the InlineDatePicker case)
	if (!GenericEntry.getViewId().equals(viewId))
	{
	_xml.startElement(_ELEMENT_EVAL, null);
	_xml.startCDATA();


	StringBuilder script = new StringBuilder(128);
	script.append("TrPage.getInstance().__handlePprResponseAction('");

	String actionURL = _facesContext.getApplication().
	getViewHandler().getActionURL(_facesContext, viewId);
	ExternalContext external = _facesContext.getExternalContext();

	script.append(external.encodeActionURL(actionURL));
	script.append("');");

	_xml.write(script.toString());

	_xml.endCDATA();
	_xml.endElement(_ELEMENT_EVAL);
	}
	}

	private void _pushPartialTarget(
	UIComponent component,
	String elementName)
	throws IOException
	{
	PPRTag tag = null;

	// If we're already inside a target, don't bother
	if (!_isInsideTarget())
	{
	if (component != null)
	{
	String clientId = component.getClientId(_facesContext);
	String renderedClientId = RenderUtils.getRendererClientId(_facesContext, component);
	if (_state.pprContext.isPartialTarget(clientId))
	{
	tag = new PPRTag(clientId, renderedClientId);
	_state.enteringPPR = component;
	}
	}
	}

	if (tag != null)
	{
	super.flush();
	tag.startUpdate(_state.pprContext, elementName);
	}

	_state.componentStack.add(tag);
	}

	private void _popPartialTarget(String elementName) throws IOException
	{
	List<PPRTag> componentStack = _state.componentStack;
	int pos = componentStack.size() - 1;
	PPRTag tag = componentStack.get(pos);
	componentStack.remove(pos);

	if (tag != null)
	tag.finishUpdate(_state.pprContext, elementName);
	}

	private boolean _isInsideTarget()
	{
	// Only use the real ResponseWriter when we are rendering
	// a partial target subtree. Otherwise, we discard all
	// output.
	return _state.forceInsideTarget \|\|
	_state.pprContext.isInsidePartialTarget();
	}


	//
	// Facelets - as of version 1.1.11 - does something
	// very strange with its ResponseWriter stack.
	// It starts with an ordinary stack (which will have
	// a PPRResponseWriter around an HtmlResponseWriter).
	// Then it treats that as an ordinary Writer, and
	// wraps it in a "StateWriter" class, which merely
	// is used to switch between passing output through
	// and buffering it. Then it takes that StateWriter
	// and uses it to cloneWithWriter() a new ResponseWriter
	// stack! As a result, we have the following stack
	// outermost to innermost:
	// PPRResponseWriter
	// HtmlResponseWriter
	// StateWriter
	// PPRResponseWriter
	// HtmlResponseWriter
	// ServletResponse's Writer
	// In the end, we have to get that "inner" PPRResponseWriter
	// to just cut it out and pass everything through. Hence,
	// this hack! So If I get a "write" call while we're
	// inside of startDocument(), assume that I must be an
	// abused PPRResponseWriter, and just put myself in
	// pass-everything-through mode
	//
	private void _disableIfNeeded()
	{
	if (_state.documentStarting)
	{
	_state = new State(_state.pprContext);
	_state.forceInsideTarget = true;
	}
	}

	private void _handleIdAttribute(String name, Object value)
	{
	if ((_state.enteringPPR != null) && "id".equals(name))
	{
	if (_LOG.isFine())
	{
	_LOG.fine("Using id {1} for element of {0}",
	new Object[]{_state.enteringPPR, value});
	}

	_state.pprContext.addRenderedPartialTarget(value.toString());
	_state.enteringPPR = null;
	}
	}

	private void _startChanges() throws IOException
	{
	if (!_state.changesStarted)
	{
	_xml.startElement(_ELEMENT_CHANGES, null);
	_state.changesStarted = true;
	}
	}

	private void _endChanges()
	throws IOException
	{
	if (_state.changesStarted)
	{
	_xml.endElement("changes");
	_state.changesStarted = false;
	}
	}

	@Override
	public void startCDATA()
	throws IOException
	{
	_xml.startCDATA();
	}

	@Override
	public void endCDATA()
	throws IOException
	{
	_xml.endCDATA();
	}

	//
	// Class representing PPR behavior associated with a tag. The
	// base class simply tells PPR when it's working with a partial target
	//
	private class PPRTag
	{
	private PPRTag(String id, String renderedId)
	{
	_id = id;
	_renderedId = renderedId != null ? renderedId : id;
	}

	public void startUpdate(
	PartialPageContextImpl pprContext,
	String elementName) throws IOException
	{
	if (_id != null)
	{
	_startChanges();
	pprContext.pushRenderedPartialTarget(_id);
	_xml.startElement(_ELEMENT_CHANGES_UPDATE, null);
	_xml.writeAttribute(_ATTRIBUTE_ID, _renderedId, null);
	_xml.startCDATA();
	_xml.flush(); // NEW

	if (_LOG.isFine())
	{
	_LOG.fine("Entering partial target id {0}", _id);
	}

	// Write out wrapper elements needed to ensure valid HTML
	_startWrapperElements(elementName);
	}
	}

	public void finishUpdate(
	PartialPageContextImpl pprContext,
	String elementName) throws IOException
	{
	if (_id != null)
	{
	if (_state.enteringPPR != null)
	{
	_LOG.warning("NO_PPR_CAPABLE_ID_FOUND_FOR_COMPONENT",
	_state.enteringPPR);
	_state.enteringPPR = null;
	}

	// Close up wrapper elements needed to ensure valid HTML
	_endWrapperElements(elementName);

	PPRResponseWriter.super.flush();

	_xml.endCDATA();
	_xml.endElement(_ELEMENT_CHANGES_UPDATE);
	_xml.flush();

	pprContext.popRenderedPartialTarget();
	_LOG.finer("Leaving partial target id {0}", _id);
	}
	}

	// Write out wrapper elements needed to generate valid HTML content
	private void _startWrapperElements(String elementName) throws IOException
	{
	// If the partial target has <tr>/<td> as its root element, we
	// need to wrap these contents such that the root element is
	// a <table>. This allows us to shove this content into a
	// div as innerHTML on the client to produce the DOM tree. Without
	// this, the resulting HTML is invalid and the DOM tree is not
	// produced.
	boolean isTR = "tr".equalsIgnoreCase(elementName);
	boolean isTD = "td".equalsIgnoreCase(elementName);

	if (isTR \|\| isTD)
	{
	PPRResponseWriter.super.startElement("table", null);

	if (isTD)
	PPRResponseWriter.super.startElement("tr", null);
	}
	}

	// Close up wrapper elements needed to generate valid HTML content
	private void _endWrapperElements(String elementName) throws IOException
	{
	// Close up <table>/<tr> tags if necessary.
	boolean isTR = "tr".equalsIgnoreCase(elementName);
	boolean isTD = "td".equalsIgnoreCase(elementName);
	if (isTR \|\| isTD)
	{
	if (isTD)
	PPRResponseWriter.super.endElement("tr");

	PPRResponseWriter.super.endElement("table");
	}
	}

	private String _id;
	private String _renderedId;
	}


	static private class State
	{
	public State(PartialPageContextImpl pprContext)
	{
	this.pprContext = pprContext;
	}

	public UIComponent enteringPPR;
	public boolean forceInsideTarget;
	public int elementDepth;
	public boolean documentStarted;
	public boolean documentStarting;
	public boolean changesStarted;
	public final List<PPRTag> componentStack = new ArrayList<PPRTag>(50);
	public final PartialPageContextImpl pprContext;
	}

	private State _state;
	private ResponseWriter _xml;
	private boolean _bufferScripts;
	private final FacesContext _facesContext = FacesContext.getCurrentInstance();

	static private final TrinidadLogger _LOG = TrinidadLogger.createTrinidadLogger(PPRResponseWriter.class);
	private static final String _ELEMENT_PARTIAL_RESPONSE = "partial-response";
	private static final String _ELEMENT_CHANGES = "changes";
	private static final String _ELEMENT_CHANGES_UPDATE = "update";
	private static final String _ELEMENT_EVAL = "eval";
	private static final String _ELEMENT_EXTENSION = "extension";
	private static final String _ATTRIBUTE_ID = "id";
	private static final List<String> _allowedIds = Arrays.asList(PartialResponseWriter.VIEW_STATE_MARKER);

	}