Added IsSupportingRTP function to simplify detecting when STUN supports RTP

[pwlib.git] / src / ptclib / vxml.cxx

/*
 * vxml.cxx
 *
 * VXML engine for pwlib library
 *
 * Copyright (C) 2002 Equivalence Pty. Ltd.
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.0 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is Portable Windows Library.
 *
 * The Initial Developer of the Original Code is Equivalence Pty. Ltd.
 *
 * Contributor(s): ______________________________________.
 *
 * $Log$
 * Revision 1.53  2004/08/09 11:10:34  csoutheren
 * Changed SetTextToSpeech to return ptr to new engine
 *
 * Revision 1.52  2004/07/28 02:01:51  csoutheren
 * Removed deadlock in some call shutdown scenarios
 *
 * Revision 1.51  2004/07/27 05:26:46  csoutheren
 * Fixed recording
 *
 * Revision 1.50  2004/07/27 00:00:41  csoutheren
 * Allowed Close to set closed flag before attepting lock of channels
 *
 * Revision 1.49  2004/07/26 07:25:02  csoutheren
 * Fixed another problem with thread starvation due to delaying inside a mutex lock
 *
 * Revision 1.48  2004/07/26 00:40:41  csoutheren
 * Fixed thread starvation problem under Linux by splitting channelMutex
 * into seperate read and write mutexes
 *
 * Revision 1.47  2004/07/23 00:59:26  csoutheren
 * Check in latest changes
 *
 * Revision 1.46  2004/07/17 09:44:12  rjongbloed
 * Fixed missing set of last write count if not actually writing frames.
 *
 * Revision 1.45  2004/07/15 03:12:42  csoutheren
 * Migrated changes from crs_vxnml_devel branch into main trunk
 *
 * Revision 1.42.2.7  2004/07/13 08:13:05  csoutheren
 * Lots of implementation of factory-based PWAVFile
 *
 * Revision 1.42.2.6  2004/07/12 08:30:17  csoutheren
 * More fixes for abstract factory implementation of PWAVFile
 *
 * Revision 1.42.2.5  2004/07/08 04:58:11  csoutheren
 * Exposed VXML playable classes to allow descendants
 *
 * Revision 1.42.2.4  2004/07/07 07:07:43  csoutheren
 * Changed PWAVFile to use abstract factories (extensively)
 * Removed redundant blocking/unblocking when using G.723.1
 * More support for call transfer
 *
 * Revision 1.42.2.3  2004/07/06 01:38:57  csoutheren
 * Changed PVXMLChannel to use PDelayChannel
 * Fixed bug where played files were deleted after playing
 *
 * Revision 1.42.2.2  2004/07/02 07:22:40  csoutheren
 * Updated for latest factory changes
 *
 * Revision 1.42.2.1  2004/06/20 11:18:03  csoutheren
 * Rewrite of resource cacheing to cache text-to-speech output
 *
 * Revision 1.42  2004/06/19 07:21:08  csoutheren
 * Change TTS engine registration to use abstract factory code
 * Started disentanglement of PVXMLChannel from PVXMLSession
 * Fixed problem with VXML session closing if played data file is not exact frame size multiple
 * Allowed PVXMLSession to be used without a VXML script
 * Changed PVXMLChannel to handle "file:" URLs
 * Numerous other small improvements and optimisations
 *
 * Revision 1.41  2004/06/02 08:29:28  csoutheren
 * Added new code from Andreas Sikkema to implement various VXML features
 *
 * Revision 1.40  2004/06/02 06:16:48  csoutheren
 * Removed unnecessary buffer copying and removed potential busy loop
 *
 * Revision 1.39  2004/05/02 05:14:43  rjongbloed
 * Fixed possible deadlock in shutdown of VXML channel/session.
 *
 * Revision 1.38  2004/04/24 06:27:56  rjongbloed
 * Fixed GCC 3.4.0 warnings about PAssertNULL and improved recoverability on
 *   NULL pointer usage in various bits of code.
 *
 * Revision 1.37  2004/03/23 04:48:42  csoutheren
 * Improved ability to start VXML scripts as needed
 *
 * Revision 1.36  2003/11/12 20:38:16  csoutheren
 * Fixed problem with incorrect sense of ContentLength header detection thanks to Andreas Sikkema
 *
 * Revision 1.35  2003/05/14 01:12:53  rjongbloed
 * Fixed test for SID frames in record silence detection on G.723.1A
 *
 * Revision 1.34  2003/04/23 11:54:53  craigs
 * Added ability to record audio
 *
 * Revision 1.33  2003/04/10 04:19:43  robertj
 * Fixed incorrect timing on G.723.1 (framed codec)
 * Fixed not using correct codec file suffix for non PCM/G.723.1 codecs.
 *
 * Revision 1.32  2003/04/08 05:09:14  craigs
 * Added ability to use commands as an audio source
 *
 * Revision 1.31  2003/03/17 08:03:07  robertj
 * Combined to the separate incoming and outgoing substream classes into
 *   a single class to make it easier to produce codec aware descendents.
 * Added G.729 substream class.
 *
 * Revision 1.30  2002/12/03 22:39:14  robertj
 * Removed get document that just returns a content length as the chunked
 *   transfer encoding makes this very dangerous.
 *
 * Revision 1.29  2002/11/19 10:36:30  robertj
 * Added functions to set anf get "file:" URL. as PFilePath and do the right
 *   things with platform dependent directory components.
 *
 * Revision 1.28  2002/11/08 03:39:27  craigs
 * Fixed problem with G.723.1 files
 *
 * Revision 1.27  2002/09/24 13:47:41  robertj
 * Added support for more vxml commands, thanks Alexander Kovatch
 *
 * Revision 1.26  2002/09/18 06:37:40  robertj
 * Added functions to load vxml directly, via file or URL. Old function
 *   intelligently picks which one to use.
 *
 * Revision 1.25  2002/09/03 04:38:14  craigs
 * Added VXML 2.0 time attribute to <break>
 *
 * Revision 1.24  2002/09/03 04:11:37  craigs
 * More changes from Alexander Kovatch
 *
 * Revision 1.23  2002/08/30 07:33:16  craigs
 * Added extra initialisations
 *
 * Revision 1.22  2002/08/30 05:05:54  craigs
 * Added changes for PVXMLGrammar from Alexander Kovatch
 *
 * Revision 1.21  2002/08/29 00:16:12  craigs
 * Fixed typo, thanks to Peter Robinson
 *
 * Revision 1.20  2002/08/28 08:05:16  craigs
 * Reorganised VXMLSession class as per code from Alexander Kovatch
 *
 * Revision 1.19  2002/08/28 05:10:57  craigs
 * Added ability to load resources via URI
 * Added cache
 *
 * Revision 1.18  2002/08/27 02:46:56  craigs
 * Removed need for application to call AllowClearCall
 *
 * Revision 1.17  2002/08/27 02:20:09  craigs
 * Added <break> command in prompt blocks
 * Fixed potential deadlock
 * Added <prompt> command in top level fields, thanks to Alexander Kovatch
 *
 * Revision 1.16  2002/08/15 04:11:16  robertj
 * Fixed shutdown problems with closing vxml session, leaks a thread.
 * Fixed potential problems with indirect channel Close() function.
 *
 * Revision 1.15  2002/08/15 02:13:10  craigs
 * Fixed problem with handle leak (maybe) and change tts files back to autodelete
 *
 * Revision 1.14  2002/08/14 15:18:07  craigs
 * Improved random filename generation
 *
 * Revision 1.13  2002/08/08 01:03:06  craigs
 * Added function to re-enable automatic call clearing on script end
 *
 * Revision 1.12  2002/08/07 13:38:14  craigs
 * Fixed bug in calculating lengths of G.723.1 packets
 *
 * Revision 1.11  2002/08/06 07:45:28  craigs
 * Added lots of stuff from OpalVXML
 *
 * Revision 1.10  2002/07/29 15:08:50  craigs
 * Added autodelete option to PlayFile
 *
 * Revision 1.9  2002/07/29 15:03:36  craigs
 * Added access to queue functions
 * Added autodelete option to AddFile
 *
 * Revision 1.8  2002/07/29 14:16:05  craigs
 * Added asynchronous VXML execution
 *
 * Revision 1.7  2002/07/17 08:34:25  craigs
 * Fixed deadlock problems
 *
 * Revision 1.6  2002/07/17 06:08:23  craigs
 * Added additional "sayas" classes
 *
 * Revision 1.5  2002/07/10 13:15:20  craigs
 * Moved some VXML classes from Opal back into PTCLib
 * Fixed various race conditions
 *
 * Revision 1.4  2002/07/05 06:28:07  craigs
 * Added OnEmptyAction callback
 *
 * Revision 1.3  2002/07/02 06:24:53  craigs
 * Added recording functions
 *
 * Revision 1.2  2002/06/28 01:30:29  robertj
 * Fixed ability to compile if do not have expat library.
 *
 * Revision 1.1  2002/06/27 05:27:49  craigs
 * Initial version
 *
 *
 */

#ifdef __GNUC__
#pragma implementation "vxml.h"
#endif

#include <ptlib.h>

#define P_DISABLE_FACTORY_INSTANCES

#if P_EXPAT

#include <ptlib/pfactory.h>
#include <ptclib/vxml.h>
#include <ptclib/memfile.h>
#include <ptclib/random.h>
#include <ptclib/http.h>

#define SMALL_BREAK_MSECS   1000
#define MEDIUM_BREAK_MSECS  2500
#define LARGE_BREAK_MSECS   5000

// LATER: Lookup what this value should be
#define DEFAULT_TIMEOUT     10000

//////////////////////////////////////////////////////////

static PString GetContentType(const PFilePath & fn)
{
  PString type = fn.GetType();

  if (type *= ".vxml")
    return "text/vxml";

  if (type *= ".wav")
    return "audio/x-wav";

  return PString::Empty();
}

///////////////////////////////////////////////////////////////

BOOL PVXMLPlayableFilename::Open(PVXMLChannel & chan, const PString & _fn, PINDEX _delay, PINDEX _repeat, BOOL _autoDelete)
{ 
  fn = _fn; 
  arg = _fn;
  if (!PFile::Exists(chan.AdjustWavFilename(fn)))
    return FALSE;

  return PVXMLPlayable::Open(chan, _delay, _repeat, _autoDelete); 
}

void PVXMLPlayableFilename::Play(PVXMLChannel & outgoingChannel)
{
  PChannel * chan = NULL;

  // check the file extension and open a .wav or a raw (.sw or .g723) file
  if ((fn.Right(4)).ToLower() == ".wav")
    chan = outgoingChannel.CreateWAVFile(fn);
  else {
    PFile * fileChan = new PFile(fn);
    if (fileChan->Open(PFile::ReadOnly))
      chan = fileChan;
    else {
      delete fileChan;
    }
  }

  if (chan == NULL)
    PTRACE(3, "PVXML\tCannot open file \"" << fn << "\"");
  else {
    PTRACE(3, "PVXML\tPlaying file \"" << fn << "\"");
    outgoingChannel.SetReadChannel(chan, TRUE);
  }
}

void PVXMLPlayableFilename::OnStop() 
{
  if (autoDelete) {
    PTRACE(3, "PVXML\tDeleting file \"" << fn << "\"");
    PFile::Remove(fn); 
  }
}

PFactory<PVXMLPlayable>::Worker<PVXMLPlayableFilename> vxmlPlayableFilenameFactory("File");

///////////////////////////////////////////////////////////////

BOOL PVXMLPlayableFilenameList::Open(PVXMLChannel & chan, const PStringArray & _list, PINDEX _delay, PINDEX _repeat, BOOL _autoDelete)
{ 
  for (PINDEX i = 0; i < _list.GetSize(); ++i) {
    PString fn = chan.AdjustWavFilename(_list[i]);
    if (PFile::Exists(fn))
      filenames.AppendString(fn);
  }

  if (filenames.GetSize() == 0)
    return FALSE;

  currentIndex = 0;

  return PVXMLPlayable::Open(chan, _delay, ((_repeat >= 0) ? _repeat : 1) * filenames.GetSize(), _autoDelete); 
}

void PVXMLPlayableFilenameList::OnRepeat(PVXMLChannel & outgoingChannel)
{
  PFilePath fn = filenames[currentIndex++ % filenames.GetSize()];

  PChannel * chan = NULL;

  // check the file extension and open a .wav or a raw (.sw or .g723) file
  if ((fn.Right(4)).ToLower() == ".wav")
    chan = outgoingChannel.CreateWAVFile(fn);
  else {
    PFile * fileChan = new PFile(fn);
    if (fileChan->Open(PFile::ReadOnly))
      chan = fileChan;
    else {
      delete fileChan;
    }
  }

  if (chan == NULL)
    PTRACE(3, "PVXML\tCannot open file \"" << fn << "\"");
  else {
    PTRACE(3, "PVXML\tPlaying file \"" << fn << "\"");
    outgoingChannel.SetReadChannel(chan, TRUE);
  }
}

void PVXMLPlayableFilenameList::OnStop() 
{
  if (autoDelete)  {
    for (PINDEX i = 0; i < filenames.GetSize(); ++i) {
      PTRACE(3, "PVXML\tDeleting file \"" << filenames[i] << "\"");
      PFile::Remove(filenames[i]); 
    }
  }
}

PFactory<PVXMLPlayable>::Worker<PVXMLPlayableFilenameList> vxmlPlayableFilenameListFactory("FileList");

///////////////////////////////////////////////////////////////

PVXMLPlayableCommand::PVXMLPlayableCommand()
{ 
  pipeCmd = NULL; 
}

void PVXMLPlayableCommand::Play(PVXMLChannel & outgoingChannel)
{
  arg.Replace("%s", PString(PString::Unsigned, sampleFrequency));
  arg.Replace("%f", format);

  // execute a command and send the output through the stream
  pipeCmd = new PPipeChannel;
  if (!pipeCmd->Open(arg, PPipeChannel::ReadOnly)) {
    PTRACE(3, "PVXML\tCannot open command " << arg);
    delete pipeCmd;
    return;
  }

  if (pipeCmd == NULL)
    PTRACE(3, "PVXML\tCannot open command \"" << arg << "\"");
  else {
    pipeCmd->Execute();
    PTRACE(3, "PVXML\tPlaying command \"" << arg << "\"");
    outgoingChannel.SetReadChannel(pipeCmd, TRUE);
  }
}

void PVXMLPlayableCommand::OnStop() 
{
  if (pipeCmd != NULL) {
    pipeCmd->WaitForTermination();
    delete pipeCmd;
  }
}

PFactory<PVXMLPlayable>::Worker<PVXMLPlayableCommand> vxmlPlayableCommandFactory("Command");

///////////////////////////////////////////////////////////////

BOOL PVXMLPlayableData::Open(PVXMLChannel & chan, const PString & /*_fn*/, PINDEX _delay, PINDEX _repeat, BOOL v)
{ 
  return PVXMLPlayable::Open(chan, _delay, _repeat, v); 
}

void PVXMLPlayableData::SetData(const PBYTEArray & _data)
{ 
  data = _data; 
}

void PVXMLPlayableData::Play(PVXMLChannel & outgoingChannel)
{
  PMemoryFile * chan = new PMemoryFile(data);
  PTRACE(3, "PVXML\tPlaying " << data.GetSize() << " bytes");
  outgoingChannel.SetReadChannel(chan, TRUE);
}

PFactory<PVXMLPlayable>::Worker<PVXMLPlayableData> vxmlPlayableDataFactory("PCM Data");

///////////////////////////////////////////////////////////////

BOOL PVXMLPlayableURL::Open(PVXMLChannel & chan, const PString & _url, PINDEX _delay, PINDEX _repeat, BOOL autoDelete)
{ 
  url = arg = _url; 
  return PVXMLPlayable::Open(chan, _delay, _repeat, autoDelete); 
}

void PVXMLPlayableURL::Play(PVXMLChannel & outgoingChannel)
{
  // open the resource
  PHTTPClient * client = new PHTTPClient;
  PMIMEInfo outMIME, replyMIME;
  int code = client->GetDocument(url, outMIME, replyMIME, FALSE);
  if ((code != 200) || (replyMIME(PHTTP::TransferEncodingTag) *= PHTTP::ChunkedTag))
    delete client;
  else {
    outgoingChannel.SetReadChannel(client, TRUE);
  }
}

PFactory<PVXMLPlayable>::Worker<PVXMLPlayableURL> vxmlPlayableURLFactory("URL");

///////////////////////////////////////////////////////////////

BOOL PVXMLRecordableFilename::Open(const PString & _arg)
{ 
  fn = _arg;
  consecutiveSilence = 0;
  return TRUE;
}

void PVXMLRecordableFilename::Record(PVXMLChannel & outgoingChannel)
{
  PChannel * chan = NULL;

  // check the file extension and open a .wav or a raw (.sw or .g723) file
  if ((fn.Right(4)).ToLower() == ".wav")
    chan = outgoingChannel.CreateWAVFile(fn, TRUE);
  else {
    PFile * fileChan = new PFile(fn);
    if (fileChan->Open(PFile::WriteOnly))
      chan = fileChan;
    else {
      delete fileChan;
    }
  }

  if (chan == NULL)
    PTRACE(3, "PVXML\tCannot open file \"" << fn << "\"");
  else {
    PTRACE(3, "PVXML\tRecording to file \"" << fn << "\"");
    outgoingChannel.SetWriteChannel(chan, TRUE);
  }

  recordStart  = PTime();
  silenceStart = PTime();
  consecutiveSilence = 0;
}

BOOL PVXMLRecordableFilename::OnFrame(BOOL isSilence)
{
  if (!isSilence) {
    silenceStart = PTime();
    consecutiveSilence = 0;
  } else {
    consecutiveSilence++;
    if ( ((consecutiveSilence % 20) == 0) &&
        (
          ((finalSilence > 0) && ((PTime() - silenceStart).GetMilliSeconds() >= finalSilence)) || 
          ((maxDuration  > 0) && ((PTime() - recordStart).GetMilliSeconds() >= maxDuration))
          )
       )
      return TRUE;
  }

  return FALSE;
}

///////////////////////////////////////////////////////////////

PVXMLCache::PVXMLCache(const PDirectory & _directory)
  : directory(_directory)
{
  if (!directory.Exists())
    directory.Create();
}

static PString MD5AsHex(const PString & str)
{
  PMessageDigest::Result digest;
  PMessageDigest5::Encode(str, digest);

  PString hexStr;
  const BYTE * data = digest.GetPointer();
  for (PINDEX i = 0; i < digest.GetSize(); ++i)
    hexStr.sprintf("%02x", (unsigned)data[i]);
  return hexStr;
}


PFilePath PVXMLCache::CreateFilename(const PString & prefix, const PString & key, const PString & fileType)
{
  PString md5   = MD5AsHex(key);
  PString md5_2 = MD5AsHex(key);

  return directory + ((prefix + "_") + md5 + fileType);
}

BOOL PVXMLCache::Get(const PString & prefix,
                     const PString & key, 
                     const PString & fileType, 
                           PString & contentType, 
                         PFilePath & dataFn)
{
  PWaitAndSignal m(*this);

  dataFn = CreateFilename(prefix, key, "." + fileType);
  PFilePath typeFn = CreateFilename(prefix, key, "_type.txt");
  if (!PFile::Exists(dataFn) || !PFile::Exists(typeFn)) {
    PTRACE(4, "Key \"" << key << "\" not found in cache");
    return FALSE;
  }

  PTextFile typeFile(typeFn, PFile::ReadOnly);
  if (!typeFile.IsOpen()) {
    PTRACE(4, "Cannot find type for cached key " << key << " in cache");
    PFile::Remove(dataFn);
    return FALSE;
  }

  typeFile.ReadLine(contentType);
  contentType.Trim();
  if (contentType.IsEmpty())
    contentType = GetContentType(dataFn);

  return TRUE;
}

void PVXMLCache::Put(const PString & prefix,
                     const PString & key, 
                     const PString & fileType, 
                     const PString & contentType,       
                   const PFilePath & fn, 
                         PFilePath & dataFn)
{
  PWaitAndSignal m(*this);

  // create the filename for the cache files
  dataFn = CreateFilename(prefix, key, "." + fileType);
  PFilePath typeFn = CreateFilename(prefix, key, "_type.txt");

  // write the content type file
  PTextFile typeFile(typeFn, PFile::WriteOnly);
  if (contentType.IsEmpty())
    typeFile.WriteLine(GetContentType(fn));
  else
    typeFile.WriteLine(contentType);

  // rename the file to the correct name
  PFile::Rename(fn, dataFn.GetFileName(), TRUE);
}

PVXMLCache & PVXMLCache::GetResourceCache()
{
  static PVXMLCache cache(PDirectory() + "cache");
  return cache;
}


PFilePath PVXMLCache::GetRandomFilename(const PString & prefix, const PString & fileType)
{
  PFilePath fn;

  // create a random temporary filename
  PRandom r;
  for (;;) {
    fn = directory + psprintf("%s_%i.%s", (const char *)prefix, r.Generate() % 1000000, (const char *)fileType);
    if (!PFile::Exists(fn))
      break;
  }

  return fn;
}

//////////////////////////////////////////////////////////

PVXMLSession::PVXMLSession(PTextToSpeech * _tts, BOOL autoDelete)
{
  vxmlThread       = NULL;
  vxmlChannel      = NULL;
  finishWhenEmpty  = TRUE;
  textToSpeech     = NULL;

  SetTextToSpeech(_tts, autoDelete);

  Initialise();
}

void PVXMLSession::Initialise()
{
  recording        = FALSE;
  allowFinish      = FALSE;
  listening        = FALSE;
  activeGrammar    = NULL;
  listening        = FALSE;
  forceEnd         = FALSE;
  currentForm      = NULL;
  currentNode      = NULL;
}

PVXMLSession::~PVXMLSession()
{
  Close();

  if ((textToSpeech != NULL) && autoDeleteTextToSpeech)
    delete textToSpeech;
}

PTextToSpeech * PVXMLSession::SetTextToSpeech(PTextToSpeech * _tts, BOOL autoDelete)
{
  PWaitAndSignal m(sessionMutex);

  if (autoDeleteTextToSpeech && (textToSpeech != NULL))
    delete textToSpeech;

  autoDeleteTextToSpeech = autoDelete;
  textToSpeech = _tts;
  return textToSpeech;
}

PTextToSpeech * PVXMLSession::SetTextToSpeech(const PString & ttsName)
{
  PWaitAndSignal m(sessionMutex);

  if (autoDeleteTextToSpeech && (textToSpeech != NULL))
    delete textToSpeech;

  autoDeleteTextToSpeech = TRUE;
  textToSpeech = PFactory<PTextToSpeech>::CreateInstance(ttsName);
  return textToSpeech;
}

BOOL PVXMLSession::Load(const PString & source)
{
  // Lets try and guess what was passed, if file exists then is file
  PFilePath file = source;
  if (PFile::Exists(file))
    return LoadFile(file);

  // see if looks like URL
  PINDEX pos = source.Find(':');
  if (pos != P_MAX_INDEX) {
    PString scheme = source.Left(pos);
    if ((scheme *= "http") || (scheme *= "https") || (scheme *= "file"))
      return LoadURL(source);
  }

  // See if is actual VXML
  if (PCaselessString(source).Find("<vxml") != P_MAX_INDEX)
    return LoadVXML(source);

  return FALSE;
}


BOOL PVXMLSession::LoadFile(const PFilePath & filename)
{
  // create a file URL from the filename
  return LoadURL(filename);
}


BOOL PVXMLSession::LoadURL(const PURL & url)
{
  // retreive the document (may be a HTTP get)
  PFilePath fn;
  PString contentType;
  if (!RetreiveResource(url, contentType, fn, FALSE)) {
    PTRACE(1, "PVXML\tCannot load document " << url);
    return FALSE;
  }

  PTextFile file(fn, PFile::ReadOnly);
  if (!file.IsOpen()) {
    PTRACE(1, "PVXML\tCannot read data from " << fn);
    return FALSE;
  }

  off_t len = file.GetLength();
  PString text;
  file.Read(text.GetPointer(len+1), len);
  len = file.GetLastReadCount();
  text.SetSize(len+1);
  text[(PINDEX)len] = '\0';

  if (!LoadVXML(text)) {
    PTRACE(1, "PVXML\tCannot load VXML in " << url);
    return FALSE;
  }

  rootURL = url;
  return TRUE;
}

BOOL PVXMLSession::LoadVXML(const PString & xmlText)
{
  PWaitAndSignal m(sessionMutex);

  allowFinish = loaded = FALSE;
  rootURL = PString::Empty();

  // parse the XML
  xmlFile.RemoveAll();
  if (!xmlFile.Load(xmlText)) {
    PTRACE(1, "PVXML\tCannot parse root document: " << GetXMLError());
    return FALSE;
  }  

  PXMLElement * root = xmlFile.GetRootElement();
  if (root == NULL)
    return FALSE;

  // reset interpeter state
  Initialise();

  // find the first form
  if ((currentForm = FindForm(PString::Empty())) == NULL)
    return FALSE;

  // start processing with this <form> element
  currentNode = currentForm;

  loaded = TRUE;
  return TRUE;
}

PURL PVXMLSession::NormaliseResourceName(const PString & src)
{
  // if resource name has a scheme, then use as is
  PINDEX pos = src.Find(':');
  if ((pos != P_MAX_INDEX) && (pos < 5))
    return src;

  if (rootURL.IsEmpty())
    return "file:" + src;

  // else use scheme and path from root document
  PURL url = rootURL;
  PStringArray path = url.GetPath();
  PString pathStr;
  if (path.GetSize() > 0) {
    pathStr += path[0];
    PINDEX i;
    for (i = 1; i < path.GetSize()-1; i++)
      pathStr += "/" + path[i];
    pathStr += "/" + src;
    url.SetPathStr(pathStr);
  }

  return url;
}


BOOL PVXMLSession::RetreiveResource(const PURL & url, 
                                       PString & contentType, 
                                     PFilePath & dataFn,
                                            BOOL useCache)
{
  BOOL stat = FALSE;

  // files on the local file system get loaded locally
  if (url.GetScheme() *= "file") {
    dataFn = url.AsFilePath();
    if (contentType.IsEmpty())
      contentType = GetContentType(dataFn);
    stat = TRUE;
  }

  // do a HTTP get when appropriate
  else if ((url.GetScheme() *= "http") || (url.GetScheme() *= "https")) {

    PFilePath fn;
    PString fileType = url.AsFilePath().GetType();

    BOOL inCache = FALSE;
    if (useCache)
      inCache = PVXMLCache::GetResourceCache().Get("url", url.AsString(), fileType, contentType, dataFn);

    if (!inCache) {

      // get a random filename
      fn = PVXMLCache::GetResourceCache().GetRandomFilename("url", fileType);

      // get the resource header information
      PHTTPClient client;
      PMIMEInfo outMIME, replyMIME;
      if (!client.GetDocument(url, outMIME, replyMIME)) {
        PTRACE(2, "PVXML\tCannot load resource " << url);
        stat =FALSE;
      } 
      
      else {

        // Get the body of the response in a PBYTEArray (might be binary data)
        PBYTEArray incomingData;
        client.ReadContentBody(replyMIME, incomingData);
        contentType = replyMIME(PHTTPClient::ContentTypeTag);

        // write the data in the file
        PFile cacheFile(fn, PFile::WriteOnly);
        cacheFile.Write(incomingData.GetPointer(), incomingData.GetSize() );

        // if we have a cache and we are using it, then save the data
        if (useCache) 
          PVXMLCache::GetResourceCache().Put("url", url.AsString(), fileType, contentType, fn, dataFn);

        // data is loaded
        stat = TRUE;
      }
    }
  }

  // files on the local file system get loaded locally
  else if (url.GetScheme() *= "file") {
    dataFn = url.AsFilePath();
    stat = TRUE;
  }

  // unknown schemes give an error
  else 
    stat = FALSE;

  return stat;
}


PXMLElement * PVXMLSession::FindForm(const PString & id)
{
  // NOTE: should have some flag to know if it is loaded
  PXMLElement * root = xmlFile.GetRootElement();
  if (root == NULL)
    return NULL;
  
  // Only handle search of top level nodes for <form> element
  PINDEX i;
  for (i = 0; i < root->GetSize(); i++) {
    PXMLObject * xmlObject = root->GetElement(i); 
    if (xmlObject->IsElement()) {
      PXMLElement * xmlElement = (PXMLElement*)xmlObject;
      if (
          (xmlElement->GetName() *= "form") && 
          (id.IsEmpty() || (xmlElement->GetAttribute("id") *= id))
         )
        return xmlElement;
    }
  }
  return NULL;
}


BOOL PVXMLSession::Open(BOOL isPCM)
{
  if (isPCM)
    return Open(VXML_PCM16);
  else
    return Open(VXML_G7231);
}

BOOL PVXMLSession::Open(const PString & _mediaFormat)
{
  mediaFormat = _mediaFormat;

  PVXMLChannel * chan = PFactory<PVXMLChannel>::CreateInstance(mediaFormat);
  if (chan == NULL) {
    PTRACE(1, "VXML\tCannot create VXML channel with format " << mediaFormat);
    return FALSE;
  }

  Close();

  // set the underlying channel
  if (!PIndirectChannel::Open(chan, chan))
    return FALSE;

  // start the VXML session in another thread
  {
    PWaitAndSignal m(sessionMutex);
    if (!chan->Open(this))
      return FALSE;
    vxmlChannel = chan;
  }

  return Execute();
}

BOOL PVXMLSession::Execute()
{
  PWaitAndSignal m(sessionMutex);

  // cannot open if no data is loaded
  if (loaded && vxmlThread == NULL) {
    threadRunning = TRUE;
    vxmlThread = PThread::Create(PCREATE_NOTIFIER(VXMLExecute), 0, PThread::NoAutoDeleteThread);
  }

  return TRUE;
}


BOOL PVXMLSession::Close()
{
  {
    PWaitAndSignal m(sessionMutex);
    if (vxmlThread != NULL) {

      // Stop condition for thread
      threadRunning = FALSE;
      forceEnd      = TRUE;
      waitForEvent.Signal();

      // Signal all syncpoints that could be waiting for things
      transferSync.Signal();
      answerSync.Signal();
      vxmlChannel->Close();

      vxmlThread->WaitForTermination();
      delete vxmlThread;
      vxmlThread = NULL;
    }

    vxmlChannel = NULL;
  }

  return PIndirectChannel::Close();
}


void PVXMLSession::VXMLExecute(PThread &, INT)
{
  while (!forceEnd && threadRunning) {

    // process current node in the VXML script
    ExecuteDialog();

    // wait for something to happen
    if (currentNode == NULL || IsPlaying())
      waitForEvent.Wait();
  }

  // Make sure the script has been run to the end so
  // submit actions etc. can be performed
  // record and audio and other user interaction commands should be skipped
  if (forceEnd) {
    PTRACE(1, "Fast forwarding through script because of forceEnd" );
    while (currentNode != NULL)
      ExecuteDialog();
  }

  OnEndSession();

  //PWaitAndSignal m(sessionMutex);
  if (vxmlChannel != NULL)
    vxmlChannel->Close();

  return;
}

void PVXMLSession::ProcessUserInput()
{
  char ch;
  {
    PWaitAndSignal m(userInputMutex);
    if (userInputQueue.size() == 0)
      return;
    ch = userInputQueue.front();
    userInputQueue.pop();
  }

  PTRACE(3, "VXML\tHandling user input " << ch);

  // recording
  if (recording) {
    if (recordDTMFTerm)
      RecordEnd();
  } 

  // playback
  else {
    if (activeGrammar != NULL)
      activeGrammar->OnUserInput(ch);
  }
}

void PVXMLSession::ExecuteDialog()
{
  // check for user input
  ProcessUserInput();

  // process any active grammars
  ProcessGrammar();

  // process current node in the VXML script
  ProcessNode();

  // Wait for the buffer to complete before continuing to the next node
  if (currentNode == NULL) {
    if (IsPlaying())
      return;
  }

  // if the current node has children, then process the first child
  else if (currentNode->IsElement() && (((PXMLElement *)currentNode)->GetElement(0) != NULL))
    currentNode = ((PXMLElement *)currentNode)->GetElement(0);

  // else process the next sibling
  else {
    // Keep moving up the parents until we find a next sibling
    while ((currentNode != NULL) && currentNode->GetNextObject() == NULL) {
      currentNode = currentNode->GetParent();
      // if we are on the backwards traversal through a <field> then wait
      // for a grammar recognition and throw events if necessary
      if (currentNode != NULL && (currentNode->IsElement() == TRUE) && (((PXMLElement*)currentNode)->GetName() *= "field")) {
        listening = TRUE;
        PlaySilence(timeout);
      }
    }

    if (currentNode != NULL)
      currentNode = currentNode->GetNextObject();
  }

  // Determine if we should quit
  if ((currentNode == NULL) && (activeGrammar == NULL) && !IsPlaying() && !IsRecording() && allowFinish && finishWhenEmpty) {
    threadRunning = FALSE;
    waitForEvent.Signal();
  }
}


void PVXMLSession::ProcessGrammar()
{
  if (activeGrammar == NULL)
    return;

  BOOL processGrammar(FALSE);

  // Stop if we've matched a grammar or have a failed recognition
  if (activeGrammar->GetState() == PVXMLGrammar::FILLED || activeGrammar->GetState() == PVXMLGrammar::NOMATCH)
    processGrammar = TRUE;

  // Stop the grammar if we've timed out
  else if (listening && !IsPlaying())   {
    activeGrammar->Stop();
    processGrammar = TRUE;
  }

  // Let the loop run again if we're still waiting to time out and haven't resolved the grammar one way or the other
  if (!processGrammar && listening)
    return;

  if (processGrammar)
  {
    PVXMLGrammar::GrammarState state = activeGrammar->GetState();
    grammarResult = activeGrammar->GetValue();
    LoadGrammar(NULL);
    listening = FALSE;

    // Stop any playback
    if (vxmlChannel != NULL) {
      vxmlChannel->FlushQueue();
      vxmlChannel->EndRecording();
    }

    // Check we're not in a menu
    if (eventName.IsEmpty()) {

      // Figure out what happened
      switch (state)
      {
      case PVXMLGrammar::FILLED:
        eventName = "filled";
        break;
      case PVXMLGrammar::NOINPUT:
        eventName = "noinput";
        break;
      case PVXMLGrammar::NOMATCH:
        eventName = "nomatch";
        break;
      default:
        ; //ERROR - unexpected grammar state
      }

      // Find the handler and move there
      PXMLElement * handler = FindHandler(eventName);
      if (handler != NULL)
        currentNode = handler;
    }
  }
}


void PVXMLSession::ProcessNode()
{
  if (currentNode == NULL)
    return;

  if (!currentNode->IsElement()) {
    if (!forceEnd)
      TraverseAudio();
    else
      currentNode = NULL;
  }

  else {
    PXMLElement * element = (PXMLElement*)currentNode;
    PCaselessString nodeType = element->GetName();
    PTRACE(3, "PVXML\t**** Processing VoiceXML element: <" << nodeType << "> ***");

    if (nodeType *= "audio") {
      if (!forceEnd)
        TraverseAudio();
    }

    else if (nodeType *= "block") {
      // check 'cond' attribute to see if this element's children are to be skipped
      // go on and process the children
    }

    else if (nodeType *= "break")
      TraverseAudio();

    else if (nodeType *= "disconnect")
      currentNode = NULL;

    else if (nodeType *= "field") {
      currentField = (PXMLElement*)currentNode;
      timeout = DEFAULT_TIMEOUT;
      TraverseGrammar();  // this will set activeGrammar
    }

    else if (nodeType *= "form") {
      // this is now the current element - go on
      currentForm = element;
      currentField = NULL;  // no active field in a new form
    }

    else if (nodeType *= "goto")
      TraverseGoto();

    else if (nodeType *= "grammar")
      TraverseGrammar();  // this will set activeGrammar

    else if (nodeType *= "record") {
      if (!forceEnd)
                  TraverseRecord();             
    }

    else if (nodeType *= "prompt") {
      if (!forceEnd) {
        // LATER:
        // check 'cond' attribute to see if the children of this node should be processed
        // check 'count' attribute to see if this node should be processed
        // flush all prompts if 'bargein' attribute is set to false

        // Update timeout of current recognition (if 'timeout' attribute is set)
        if (element->HasAttribute("timeout")) {
          PTimeInterval timeout = StringToTime(element->GetAttribute("timeout"));
        }
      }
    }

    else if (nodeType *= "say-as") {
      if (!forceEnd) {
      }
    }

    else if (nodeType *= "value") {
      if (!forceEnd)
        TraverseAudio();
    }

    else if (nodeType *= "var")
      TraverseVar();

    else if (nodeType *= "if") 
      TraverseIf();

    else if (nodeType *= "exit") 
      TraverseExit();

    else if (nodeType *= "menu")  {
      if (!forceEnd) {
        TraverseMenu();
        eventName = "menu";
      }
    }

    else if (nodeType *= "choice") {
      if (!TraverseChoice(grammarResult))
        defaultDTMF++;
      else {
        // If the correct choice has been found, 
        /// make sure everything is reset correctly
        eventName.MakeEmpty();
        grammarResult.MakeEmpty();
        defaultDTMF = 1;
      }
    }

    else if (nodeType *= "transfer") {
      if (!forceEnd) 
        TraverseTransfer();
    }

    else if (nodeType *= "submit")
      TraverseSubmit();

    else if (nodeType *= "property")
      TraverseProperty();
  }
}

BOOL PVXMLSession::OnUserInput(const PString & str)
{
  {
    PWaitAndSignal m(userInputMutex);
    for (PINDEX i = 0; i < str.GetLength(); i++)
      userInputQueue.push(str[i]);
  }
  waitForEvent.Signal();
  return TRUE;
}

BOOL PVXMLSession::TraverseRecord()
{
  if (currentNode->IsElement()) {
    
    PString strName;
    PXMLElement * element = (PXMLElement *)currentNode;
    
    // Get the name (name)
    if (element->HasAttribute("name"))
      strName = element->GetAttribute("name");
    else if (element->HasAttribute("id"))
      strName = element->GetAttribute("id");
    
    // Get the destination filename (dest)
    PString strDest;
    if (element->HasAttribute("dest")) 
      strDest = element->GetAttribute("dest");
    
    // see if we need a beep
    if (element->GetAttribute("beep").ToLower() *= "true") {
      PBYTEArray beepData;
      GetBeepData(beepData, 1000);
      if (beepData.GetSize() != 0)
        PlayData(beepData);
    }

    if (strDest.IsEmpty()) {
      PTime now;
      strDest = GetVar("session.telephone.dnis" ) + "_" + GetVar( "session.telephone.ani" ) + "_" + now.AsString( "yyyyMMdd_hhmmss") + ".wav";
    }
    
    // For some reason, if the file is there the create 
    // seems to fail. 
    PFile::Remove(strDest);
    PFilePath file(strDest);
    
    // Get max record time (maxtime)
    PTimeInterval maxTime = PMaxTimeInterval;
    if (element->HasAttribute("maxtime")) 
      maxTime = StringToTime(element->GetAttribute("maxtime"));
    
    // Get terminating silence duration (finalsilence)
    PTimeInterval termTime(3000);
    if (element->HasAttribute("finalsilence")) 
      termTime = StringToTime(element->GetAttribute("finalsilence"));
    
    // Get dtmf term (dtmfterm)
    BOOL dtmfTerm = TRUE;
    if (element->HasAttribute("dtmfterm"))
      dtmfTerm = !(element->GetAttribute("dtmfterm").ToLower() *= "false");
    
    // create a semaphore, and then wait for the recording to terminate
    StartRecording(file, dtmfTerm, maxTime, termTime);
    recordSync.Wait(maxTime);
    
    if (!recordSync.Wait(maxTime)) {
      // The Wait() has timed out, to signal that the record timed out.
      // This is VXML version 2 property, but nice.
      // So it's possible to detect if the record timed out from within the 
      // VXML script
      SetVar(strName + "$.maxtime", "true");
    }
    else {
      // Normal hangup before timeout
      SetVar( strName + "$.maxtime", "false");
    }

    // when this returns, we are done
    EndRecording();
  }
  
  return TRUE;
}

PString PVXMLSession::GetXMLError() const
{
  return psprintf("(%i:%i) ", xmlFile.GetErrorLine(), xmlFile.GetErrorColumn()) + xmlFile.GetErrorString();
}

PString PVXMLSession::EvaluateExpr(const PString & oexpr)
{
  PString expr = oexpr.Trim();

  // see if all digits
  PINDEX i;
  BOOL allDigits = TRUE;
  for (i = 0; i < expr.GetLength(); i++) {
    allDigits = allDigits && isdigit(expr[i]);
  }

  if (allDigits)
    return expr;

  return GetVar(expr);
}

PString PVXMLSession::GetVar(const PString & ostr) const
{
  PString str = ostr;
  PString scope;

  // get scope
  PINDEX pos = str.Find('.');
  if (pos != P_MAX_INDEX) {
    scope = str.Left(pos);
    str   = str.Mid(pos+1);
  }

  // process session scope
  if (scope.IsEmpty() || (scope *= "session")) {
    if (sessionVars.Contains(str))
      return sessionVars(str);
  }

  // assume any other scope is actually document or application
  return documentVars(str);
}

void PVXMLSession::SetVar(const PString & ostr, const PString & val)
{
  PString str = ostr;
  PString scope;

  // get scope
  PINDEX pos = str.Find('.');
  if (pos != P_MAX_INDEX) {
    scope = str.Left(pos);
    str   = str.Mid(pos+1);
  }

  // do session scope
  if (scope.IsEmpty() || (scope *= "session")) {
    sessionVars.SetAt(str, val);
    return;
  }

  PTRACE(3, "PVXML\tDocument: " << str << " = \"" << val << "\"");

  // assume any other scope is actually document or application
  documentVars.SetAt(str, val);
}

BOOL PVXMLSession::PlayFile(const PString & fn, PINDEX repeat, PINDEX delay, BOOL autoDelete)
{
  if (vxmlChannel == NULL || !vxmlChannel->QueueFile(fn, repeat, delay, autoDelete))
    return FALSE;

  AllowClearCall();

  return TRUE;
}

BOOL PVXMLSession::PlayCommand(const PString & cmd, PINDEX repeat, PINDEX delay)
{
  if (vxmlChannel == NULL || !vxmlChannel->QueueCommand(cmd, repeat, delay))
    return FALSE;

  AllowClearCall();

  return TRUE;
}

BOOL PVXMLSession::PlayData(const PBYTEArray & data, PINDEX repeat, PINDEX delay)
{
  if (vxmlChannel == NULL || !vxmlChannel->QueueData(data, repeat, delay))
    return FALSE;

  AllowClearCall();

  return TRUE;
}


void PVXMLSession::GetBeepData(PBYTEArray & data, unsigned ms)
{
  if (vxmlChannel != NULL)
    vxmlChannel->GetBeepData(data, ms);
}

BOOL PVXMLSession::PlaySilence(const PTimeInterval & timeout)
{
  return PlaySilence((PINDEX)timeout.GetMilliSeconds());
}

BOOL PVXMLSession::PlaySilence(PINDEX msecs)
{
  PBYTEArray nothing;
  if (vxmlChannel == NULL || !vxmlChannel->QueueData(nothing, 1, msecs))
    return FALSE;

  AllowClearCall();

  return TRUE;
}

BOOL PVXMLSession::PlayResource(const PURL & url, PINDEX repeat, PINDEX delay)
{
  if (vxmlChannel == NULL || !vxmlChannel->QueueResource(url, repeat, delay))
    return FALSE;

  AllowClearCall();

  return TRUE;
}

BOOL PVXMLSession::LoadGrammar(PVXMLGrammar * grammar)
{
  if (activeGrammar != NULL) {
    delete activeGrammar;
    activeGrammar = FALSE;
  }

  activeGrammar = grammar;

  return TRUE;
}

BOOL PVXMLSession::PlayText(const PString & _text, 
                    PTextToSpeech::TextType type, 
                                     PINDEX repeat, 
                                     PINDEX delay)
{
  PStringArray list;
  BOOL useCache = !(GetVar("caching") *= "safe");
  if (!ConvertTextToFilenameList(_text, type, list, useCache) || (list.GetSize() == 0)) {
    PTRACE(1, "PVXML\tCannot convert text to speech");
    return FALSE;
  }

  PVXMLPlayableFilenameList * playable = new PVXMLPlayableFilenameList;
  if (!playable->Open(*vxmlChannel, list, delay, repeat, !useCache)) {
    delete playable;
    PTRACE(1, "PVXML\tCannot create playable for filename list");
    return FALSE;
  }

  return vxmlChannel->QueuePlayable(playable);
}

BOOL PVXMLSession::ConvertTextToFilenameList(const PString & _text, PTextToSpeech::TextType type, PStringArray & filenameList, BOOL useCache)
{
  PString prefix = psprintf("tts%i", type);

  PStringArray lines = _text.Lines();
  for (PINDEX i = 0; i < lines.GetSize(); i++) {

    PString text = lines[i].Trim();
    if (text.IsEmpty())
      continue;

    BOOL spoken = FALSE;
    PFilePath dataFn;

    // see if we have converted this text before
    PString contentType;
    if (useCache)
      spoken = PVXMLCache::GetResourceCache().Get(prefix, text, "wav", contentType, dataFn);

    // if not cached, then use the text to speech converter
    if (!spoken) {
      PFilePath tmpfname;
      if (textToSpeech != NULL) {
        tmpfname = PVXMLCache::GetResourceCache().GetRandomFilename("tts", "wav");
        if (!textToSpeech->OpenFile(tmpfname)) {
          PTRACE(2, "PVXML\tcannot open file " << tmpfname);
        } else {
          spoken = textToSpeech->Speak(text, type);
          if (!textToSpeech->Close()) {
            PTRACE(2, "PVXML\tcannot close TTS engine");
          }
        }
        textToSpeech->Close();
        if (useCache)
          PVXMLCache::GetResourceCache().Put(prefix, text, "wav", contentType, tmpfname, dataFn);
        else
          dataFn = tmpfname;
      }
    }

    if (!spoken) {
      PTRACE(2, "PVXML\tcannot speak text using TTS engine");
    } else 
      filenameList.AppendString(dataFn);
  }

  return filenameList.GetSize() > 0;
}

void PVXMLSession::SetPause(BOOL _pause)
{
  if (vxmlChannel != NULL)
    vxmlChannel->SetPause(_pause);
}


BOOL PVXMLSession::IsPlaying() const
{
  return (vxmlChannel != NULL) && vxmlChannel->IsPlaying();
}

BOOL PVXMLSession::StartRecording(const PFilePath & /*_recordFn*/, 
                                               BOOL /*_recordDTMFTerm*/, 
                              const PTimeInterval & /*_recordMaxTime*/, 
                              const PTimeInterval & /*_recordFinalSilence*/)
{
  /*
  recording          = TRUE;
  recordFn           = _recordFn;
  recordDTMFTerm     = _recordDTMFTerm;
  recordMaxTime      = _recordMaxTime;
  recordFinalSilence = _recordFinalSilence;

  if (incomingChannel != NULL) {
    PXMLElement* element = (PXMLElement*) currentNode;
    if ( element->HasAttribute("name")) {
      PString chanName = element->GetAttribute("name");
      incomingChannel->SetName(chanName);
    }
    return incomingChannel->StartRecording(recordFn, (unsigned )recordFinalSilence.GetMilliSeconds());
  }

  */

  return FALSE;
}

void PVXMLSession::RecordEnd()
{
  if (recording)
    recordSync.Signal();
}

BOOL PVXMLSession::EndRecording()
{
  if (recording) {
          recording = FALSE;
    if (vxmlChannel != NULL)
      return vxmlChannel->EndRecording();
  }

  return FALSE;
}


BOOL PVXMLSession::IsRecording() const
{
  return (vxmlChannel != NULL) && vxmlChannel->IsRecording();
}

PWAVFile * PVXMLSession::CreateWAVFile(const PFilePath & fn, PFile::OpenMode mode, int opts, unsigned fmt)
{ 
  if (!fn.IsEmpty())
    return new PWAVFile(fn, mode, opts, fmt);

  return new PWAVFile(mode, opts, fmt); 
}

void PVXMLSession::AllowClearCall()
{
  allowFinish = TRUE;
}

BOOL PVXMLSession::TraverseAudio()
{
  if (!currentNode->IsElement()) {
    PlayText(((PXMLData *)currentNode)->GetString());
  }

  else {
    PXMLElement * element = (PXMLElement *)currentNode;

    if (element->GetName() *= "value") {
      PString className = element->GetAttribute("class");
      PString value = EvaluateExpr(element->GetAttribute("expr"));
      SayAs(className, value);
    }

    else if (element->GetName() *= "sayas") {
      PString className = element->GetAttribute("class");
      PXMLObject * object = element->GetElement();
      if (!object->IsElement()) {
        PString text = ((PXMLData *)object)->GetString();
        SayAs(className, text);
      }
    }

    else if (element->GetName() *= "break") {

      // msecs is VXML 1.0
      if (element->HasAttribute("msecs"))
        PlaySilence(element->GetAttribute("msecs").AsInteger());

      // time is VXML 2.0
      else if (element->HasAttribute("time")) {
        PTimeInterval time = StringToTime(element->GetAttribute("time"));
        PlaySilence(time);
      }
      
      else if (element->HasAttribute("size")) {
        PString size = element->GetAttribute("size");
        if (size *= "none")
          ;
        else if (size *= "small")
          PlaySilence(SMALL_BREAK_MSECS);
        else if (size *= "large")
          PlaySilence(LARGE_BREAK_MSECS);
        else 
          PlaySilence(MEDIUM_BREAK_MSECS);
      } 
      
      // default to medium pause
      else {
        PlaySilence(MEDIUM_BREAK_MSECS);
      }
    }

    else if (element->GetName() *= "audio") {
      BOOL loaded = FALSE;

      if (element->HasAttribute("src")) {

        PString str = element->GetAttribute("src").Trim();
        if (!str.IsEmpty() && (str[0] == '|')) {
          loaded = TRUE;
          PlayCommand(str.Mid(1));
        } 
        
        else {
          // get a normalised name for the resource
          PFilePath fn; 
          PURL url = NormaliseResourceName(str);

          // load the resource from the cache
          PString contentType;
          BOOL useCache = !(GetVar("caching") *= "safe") && !(element->GetAttribute("caching") *= "safe");
          if (RetreiveResource(url, contentType, fn, useCache)) {
            PWAVFile * wavFile = vxmlChannel->CreateWAVFile(fn);
            if (wavFile == NULL)
              PTRACE(3, "PVXML\tCannot create audio file " + fn);
            else if (!wavFile->IsOpen())
              delete wavFile;
            else {
              loaded = TRUE;
              PlayFile(fn, 0, 0, !useCache);   // make sure we delete the file if not cacheing
            }
          }
        }

        if (loaded) {
          // skip to the next node
          if (element->HasSubObjects())
                                          currentNode = element->GetElement(element->GetSize() - 1);
        }
      }
    }

    else 
      PTRACE(3, "PVXML\tUnknown audio tag " << element->GetName() << " encountered");
  }

  return TRUE;
}


BOOL PVXMLSession::TraverseGoto()               // <goto>
{
  PAssert(currentNode != NULL, "ProcessGotoElement(): Expected valid node");
  if (currentNode == NULL)
    return FALSE;
  
  // LATER: handle expr, expritem, fetchaudio, fetchhint, fetchtimeout, maxage, maxstale
  
  PAssert(currentNode->IsElement(), "ProcessGotoElement(): Expected element");
  
  // nextitem
  PString nextitem = ((PXMLElement*)currentNode)->GetAttribute("nextitem");
  if (!nextitem.IsEmpty()) {
    // LATER: Take out the optional #
    currentForm = FindForm(nextitem);
    currentNode = currentForm;
    if (currentForm == NULL) {
      // LATER: throw "error.semantic" or "error.badfetch" -- lookup which
      return FALSE;
    }
    return TRUE;
  }
  
  // next
  PString next = ((PXMLElement*)currentNode)->GetAttribute("next");
  // LATER: fixup filename to prepend path
  if (!next.IsEmpty()) { 
    if (next[0] == '#') {
      next = next.Right( next.GetLength() -1 );
      currentForm = FindForm(next);
      currentNode = currentForm;
      // LATER: throw "error.semantic" or "error.badfetch" -- lookup which
      return currentForm != NULL;
    }
    else {
      PURL url = NormaliseResourceName(next);
      return LoadURL(url) && (currentForm != NULL);
    }
  }
  return FALSE;
}

BOOL PVXMLSession::TraverseGrammar()            // <grammar>
{
  // LATER: A bunch of work to do here!

  // For now we only support the builtin digits type and do not parse any grammars.

  // NOTE: For now we will process both <grammar> and <field> here.
  // NOTE: Later there needs to be a check for <grammar> which will pull
  //       out the text and process a grammar like '1 | 2'

  // Right now we only support one active grammar.
  if (activeGrammar != NULL) {
    PTRACE(2, "PVXML\tWarning: can only process one grammar at a time, ignoring previous grammar");
    delete activeGrammar;
    activeGrammar = NULL;
  }

  PVXMLGrammar * newGrammar = NULL;

  // Is this a built-in type?
  PString type = ((PXMLElement*)currentNode)->GetAttribute("type");
  if (!type.IsEmpty()) {
    PStringArray tokens = type.Tokenise("?;", TRUE);
    PString builtintype;
    if (tokens.GetSize() > 0)
      builtintype = tokens[0];

    if (builtintype *= "digits") {
      PINDEX minDigits(1);
      PINDEX maxDigits(100);

      // look at each parameter
      for (PINDEX i(1); i < tokens.GetSize(); i++) {
        PStringArray params = tokens[i].Tokenise("=", TRUE);
        if (params.GetSize() == 2) {
          if (params[0] *= "minlength") {
            minDigits = params[1].AsInteger();
          }
          else if (params[0] *= "maxlength") {
            maxDigits = params[1].AsInteger();
          }
          else if (params[0] *= "length") {
            minDigits = maxDigits = params[1].AsInteger();
          }
        }
        else {
          // Invalid parameter skipped
          // LATER: throw 'error.semantic'
        }
      }
      newGrammar = new PVXMLDigitsGrammar((PXMLElement*)currentNode, minDigits, maxDigits, "");
    }
    else {
      // LATER: throw 'error.unsupported'
      return FALSE;
    }
  }

  if (newGrammar != NULL)
    return LoadGrammar(newGrammar);

  return TRUE;
}

// Finds the proper event hander for 'noinput', 'filled', 'nomatch' and 'error'
// by searching the scope hiearchy from the current from
PXMLElement * PVXMLSession::FindHandler(const PString & event)
{
  PAssert(currentNode->IsElement(), "Expected 'PXMLElement' in PVXMLSession::FindHandler");
  PXMLElement * tmp = (PXMLElement *)currentNode;
  PXMLElement * handler = NULL;

  // Look in all the way up the tree for a handler either explicitly or in a catch
  while (tmp != NULL) {
    // Check for an explicit hander - i.e. <error>, <filled>, <noinput>, <nomatch>, <help>
    if ((handler = tmp->GetElement(event)) != NULL)
      return handler;

    // Check for a <catch>
    if ((handler = tmp->GetElement("catch")) != NULL) {
      PString strCond = handler->GetAttribute("cond");
      if (strCond.Find(event))
        return handler;
    }

    tmp = tmp->GetParent();
  }

  return NULL;
}

void PVXMLSession::SayAs(const PString & className, const PString & _text)
{
  PString text = _text.Trim();
  if (!text.IsEmpty()) {
    PTextToSpeech::TextType type = PTextToSpeech::Literal;

    if (className *= "digits")
      type = PTextToSpeech::Digits;

    else if (className *= "literal")
      type = PTextToSpeech::Literal;

    else if (className *= "number")
      type = PTextToSpeech::Number;

    else if (className *= "currency")
      type = PTextToSpeech::Currency;

    else if (className *= "time")
      type = PTextToSpeech::Time;

    else if (className *= "date")
      type = PTextToSpeech::Date;

    else if (className *= "phone")
      type = PTextToSpeech::Phone;

    else if (className *= "ipaddress")
      type = PTextToSpeech::IPAddress;

    else if (className *= "duration")
      type = PTextToSpeech::Duration;

    else
      PlayText(text, type);
  }
}

PTimeInterval PVXMLSession::StringToTime(const PString & str)
{
  PTimeInterval timeout;

  long msecs = str.AsInteger();
  if (str.Find("ms") != P_MAX_INDEX)
    ;
  else if (str.Find("s") != P_MAX_INDEX)
    msecs = msecs * 1000;

  return PTimeInterval(msecs);
}

BOOL PVXMLSession::TraverseTransfer()
{
  PVXMLTransferOptions opts;

  PAssert(currentNode != NULL, "TraverseTransfer(): Expected valid node");
  if (currentNode == NULL)
    return FALSE;

  PAssert(currentNode->IsElement(), "TraverseTransfer(): Expected element");
  
  // Retreive parameters
  PString dest = ((PXMLElement*)currentNode)->GetAttribute("dest");
  PString source = ((PXMLElement*)currentNode)->GetAttribute("source");
  PString connectTimeoutStr = ((PXMLElement*)currentNode)->GetAttribute("connecttimeout");
  PString bridgeStr = ((PXMLElement*)currentNode)->GetAttribute("dest");
  
  BOOL bridge = bridgeStr *= "true";
  PINDEX connectTimeout = connectTimeoutStr.AsInteger();

  if ((connectTimeout < 2) && (connectTimeout > 30))
    connectTimeout = 30;

  if (dest.Find("phone://") == P_MAX_INDEX)
    return FALSE;
  dest.Delete(0, 8);

  if (source.Find("phone://") == P_MAX_INDEX)
    return FALSE;
  source.Delete(0, 8);

  opts.SetCallingToken(callingCallToken );
  opts.SetDestinationDNR(dest);
  opts.SetSourceDNR(source);
  opts.SetTimeout(connectTimeout);
  opts.SetBridge(bridge);

  DoTransfer(opts);

  // Wait for the transfer result signal
  transferSync.Wait();

  return TRUE;
}

void PVXMLSession::OnTransfer(const PVXMLTransferResult & args)
{
  // transfer has ended, save result
  SetVar(args.GetName(), args);

  // Signal transfer initiator that the transfer has ended and the VXML can 
  // continue
  transferSync.Signal();
}

BOOL PVXMLSession::TraverseIf()
{
  // If 'cond' parameter evaluates to true, enter child entities, else
  // go to next element.

  PString condition = ((PXMLElement*)currentNode)->GetAttribute("cond");

  // Find comparison type
  PINDEX location = condition.Find("==");
  BOOL isEqual = (location < condition.GetSize());

  if (isEqual) {
    // Find var name
    PString varname = condition.Left(location);

    // Find value, skip '=' signs
    PString cond_value = condition.Right(condition.GetSize() - (location + 3));
    
    // check if var value equals value from condition and if not skip child elements
    PString value = GetVar(varname);
    if (cond_value == value) {
      PTRACE( 3, "VXMLSess\t\tCondition matched \"" << condition << "\"" );
    } else {
      PTRACE( 3, "VXMLSess\t\tCondition \"" << condition << "\"did not match, " << varname << " == " << value );
      if (currentNode->IsElement()) {
        PXMLElement* element = (PXMLElement*) currentNode;
        if (element->HasSubObjects()) {
          // Step to last child element (really last element is NULL?)
          currentNode = element->GetElement(element->GetSize() - 1);
        }
      }
    }
  }

  else {
    PTRACE( 1, "\tPVXMLSession, <if> element contains condition with operator other than ==, not implemented" );
    return FALSE;
  }

  return TRUE;
}

BOOL PVXMLSession::TraverseExit()
{
  currentNode = NULL;
  forceEnd    = TRUE;
  waitForEvent.Signal();
  return TRUE;
}


BOOL PVXMLSession::TraverseSubmit()
{
  BOOL result = FALSE;

  // Do HTTP client stuff here

  // Find out what to submit, for now, only support a WAV file
  PXMLElement * element = (PXMLElement *)currentNode;

  if (!element->HasAttribute("namelist")){
    PTRACE(1, "VXMLSess\t<submit> does not contain \"namelist\" parameter");
    return FALSE;
  }

  PString name = element->GetAttribute("namelist");

  if (name.Find(" ") < name.GetSize()) {
    PTRACE(1, "VXMLSess\t<submit> does not support more than one value in \"namelist\" parameter");
    return FALSE;
  }

  if (!element->HasAttribute("next")) {
    PTRACE(1, "VXMLSess\t<submit> does not contain \"next\" parameter");
    return FALSE;
  }

  PString url = element->GetAttribute("next");

  if (url.Find( "http://" ) > url.GetSize()) {
    PTRACE(1, "VXMLSess\t<submit> needs a full url as the \"next\" parameter");
    return FALSE;
  }

  if (!(GetVar(name + ".type") == "audio/x-wav" )) {
    PTRACE(1, "VXMLSess\t<submit> does not (yet) support submissions of types other than \"audio/x-wav\"");
    return FALSE;
  }

  PString fileName = GetVar(name + ".filename");

  if (!(element->HasAttribute("method"))) {
    PTRACE(1, "VXMLSess\t<submit> does not (yet) support default method type \"get\"");
    return FALSE;
  }

  if ( !PFile::Exists(fileName )) {
    PTRACE(1, "VXMLSess\t<submit> cannot find file " << fileName);
    return FALSE;
  }

  PString fileNameOnly;
  int pos = fileName.FindLast( "/" );
  if (pos < fileName.GetLength()) {
    fileNameOnly = fileName.Right( ( fileName.GetLength() - pos ) - 1 );
  }
  else {
    pos = fileName.FindLast("\\");
    if (pos < fileName.GetSize()) {
      fileNameOnly = fileName.Right((fileName.GetLength() - pos) - 1);
    }
    else {
      fileNameOnly = fileName;
    }
  }

  PHTTPClient client;
  PMIMEInfo sendMIME, replyMIME;

  if (element->GetAttribute("method") *= "post") {

    //                            1         2         3        4123
    PString boundary = "--------012345678901234567890123458VXML";

    sendMIME.SetAt( PHTTP::ContentTypeTag, "multipart/form-data; boundary=" + boundary);
    sendMIME.SetAt( PHTTP::UserAgentTag, "PVXML TraverseSubmit" );
    sendMIME.SetAt( "Accept", "text/html" );

    // After this all boundaries have a "--" prepended
    boundary = "--" + boundary;

    // Create the mime header
    // First set the primary boundary
    PString mimeHeader = boundary + "\r\n";

    // Add content disposition
    mimeHeader += "Content-Disposition: form-data; name=\"voicemail\"; filename=\"" + fileNameOnly + "\"\r\n";

    // Add content type
    mimeHeader += "Content-Type: audio/wav\r\n\r\n";

    // Create the footer and add the closing of the content with a CR/LF
    PString mimeFooter = "\r\n";

    // Copy the header, buffer and footer together in one PString

    // Load the WAV file into memory
    PFile file( fileName, PFile::ReadOnly );
    int size = file.GetLength();
    PString mimeThing;

    // Make PHP happy?
    // Anyway, this shows how to add more variables, for when namelist containes more elements
    PString mimeMaxFileSize = boundary + "\r\nContent-Disposition: form-data; name=\"MAX_FILE_SIZE\"\r\n\r\n3000000\r\n";

    // Finally close the body with the boundary again, but also add "--"
    // to show this is the final boundary
    boundary = boundary + "--";
    mimeFooter += boundary + "\r\n";
    mimeHeader = mimeMaxFileSize + mimeHeader;
    mimeThing.SetSize( mimeHeader.GetSize() + size + mimeFooter.GetSize() );

    // Copy the header to the result
    memcpy( mimeThing.GetPointer(), mimeHeader.GetPointer(), mimeHeader.GetLength());

    // Copy the contents of the file to the mime result
    file.Read( mimeThing.GetPointer() + mimeHeader.GetLength(), size );

    // Copy the footer to the result
    memcpy( mimeThing.GetPointer() + mimeHeader.GetLength() + size, mimeFooter.GetPointer(), mimeFooter.GetLength());

    // Send the POST request to the server
    result = client.PostData( url, sendMIME, mimeThing, replyMIME );

    // TODO, Later:
    // Remove file?
    // Load reply from server as new VXML docuemnt ala <goto>
  }

  else {
    if (element->GetAttribute("method") != "get") {
      PTRACE(1, "VXMLSess\t<submit> does not (yet) support method type \"" << element->GetAttribute( "method" ) << "\"");
      return FALSE;
    }

    PString getURL = url + "?" + name + "=" + GetVar( name );

    client.GetDocument( url, sendMIME, replyMIME );
    // TODO, Later:
    // Load reply from server as new VXML document ala <goto>
  }

  if (!result) {
    PTRACE( 1, "VXMLSess\t<submit> to server failed with "
        << client.GetLastResponseCode() << " "
        << client.GetLastResponseInfo() );
  }

  return result;
}

BOOL PVXMLSession::TraverseProperty()
{
  PXMLElement* element = (PXMLElement *) currentNode;
  if (element->HasAttribute("name"))
    SetVar(element->GetAttribute("name"), element->GetAttribute("value"));

  return TRUE;
}


BOOL PVXMLSession::TraverseMenu()
{
  BOOL result = FALSE;
  PVXMLGrammar * newGrammar = new PVXMLDigitsGrammar((PXMLElement*) currentNode, 1, 1, "" );
  LoadGrammar(newGrammar);
  result = TRUE;
  return result;
}

BOOL PVXMLSession::TraverseChoice(const PString & grammarResult)
{
  // Iterate over all choice elements starting at currentnode
  BOOL result = FALSE;

  PXMLElement* element = (PXMLElement *) currentNode;
  // Current node is a choice element

  PString dtmf = element->GetAttribute( "dtmf" );

  if (dtmf.IsEmpty())
    dtmf = PString(PString::Unsigned, defaultDTMF);

  // Check if DTMF value for grammarResult matches the DTMF value for the choice
  if (dtmf == grammarResult) {

    // Find the form at next parameter
    PString formID = element->GetAttribute( "next" );

    PTRACE(2, "VXMLsess\tFound form id " << formID );

    if (!formID.IsEmpty()) {
      formID = formID.Right( formID.GetLength() - 1 );
      currentNode = FindForm( formID );
      if (currentNode != NULL)
        result = TRUE;
    }
  }
  return result;
}

BOOL PVXMLSession::TraverseVar()
{
  BOOL result = FALSE;

  PXMLElement* element = (PXMLElement *) currentNode;

  PString name = element->GetAttribute( "name" );
  PString expr = element->GetAttribute( "expr" );

  if (name.IsEmpty() || expr.IsEmpty()) {
    PTRACE( 1, "VXMLSess\t<var> has a problem with its parameters, name=\"" << name << "\", expr=\"" << expr << "\"" );
  }
  else {
    SetVar(name, expr);
    result = TRUE;
  }

  return result;
}


void PVXMLSession::OnEndRecording(const PString & /*channelName*/)
{
  //SetVar(channelName + ".size", PString(incomingChannel->GetWAVFile()->GetDataLength() ) );
  //SetVar(channelName + ".type", "audio/x-wav" );
  //SetVar(channelName + ".filename", incomingChannel->GetWAVFile()->GetName() );
}


void PVXMLSession::Trigger()
{
  waitForEvent.Signal();
}



/////////////////////////////////////////////////////////////////////////////////////////

PVXMLGrammar::PVXMLGrammar(PXMLElement * _field)
  : field(_field), state(PVXMLGrammar::NOINPUT)
{
}

//////////////////////////////////////////////////////////////////

PVXMLMenuGrammar::PVXMLMenuGrammar(PXMLElement * _field)
  : PVXMLGrammar(_field)
{
}

//////////////////////////////////////////////////////////////////

PVXMLDigitsGrammar::PVXMLDigitsGrammar(PXMLElement * _field, PINDEX _minDigits, PINDEX _maxDigits, PString _terminators)
  : PVXMLGrammar(_field),
  minDigits(_minDigits),
  maxDigits(_maxDigits),
  terminators(_terminators)
{
  PAssert(_minDigits <= _maxDigits, "Error - invalid grammar parameter");
}

BOOL PVXMLDigitsGrammar::OnUserInput(const char ch)
{
  // Ignore any other keys if we've already filled the grammar
  if (state == PVXMLGrammar::FILLED || state == PVXMLGrammar::NOMATCH)
    return TRUE;

  // is this char the terminator?
  if (terminators.Find(ch) != P_MAX_INDEX) {
    state = (value.GetLength() >= minDigits && value.GetLength() <= maxDigits) ? 
      PVXMLGrammar::FILLED : 
      PVXMLGrammar::NOMATCH;
    return TRUE;
  }

  // Otherwise add to the grammar and check to see if we're done
  value += ch;
  if (value.GetLength() == maxDigits) {
    state = PVXMLGrammar::FILLED;   // the grammar is filled!
    return TRUE;
  }

  return FALSE;
}


void PVXMLDigitsGrammar::Stop()
{
  // Stopping recognition here may change the state if something was
  // recognized but it didn't fill the number of digits requested
  if (!value.IsEmpty())
    state = PVXMLGrammar::NOMATCH;
  // otherwise the state will stay as NOINPUT
}

//////////////////////////////////////////////////////////////////

PVXMLChannel::PVXMLChannel(unsigned _frameDelay, PINDEX frameSize)
  : PDelayChannel(DelayReadsAndWrites, _frameDelay, frameSize)
{
  vxmlInterface = NULL; 

  sampleFrequency = 8000;
  closed          = FALSE;

  recording       = FALSE;
  recordable      = NULL;

  playing         = FALSE;
  silentCount     = 20;         // wait 20 frames before playing the OGM
  paused          = FALSE;
}

BOOL PVXMLChannel::Open(PVXMLChannelInterface * _vxmlInterface)
{
  vxmlInterface = _vxmlInterface;
  return TRUE;
}

PVXMLChannel::~PVXMLChannel()
{
  EndRecording();
}

BOOL PVXMLChannel::IsOpen() const
{
  return !closed;
}

BOOL PVXMLChannel::Close()
{ 
  closed = TRUE; 

  PDelayChannel::Close(); 
  return TRUE; 
}

PString PVXMLChannel::AdjustWavFilename(const PString & ofn)
{
  if (wavFilePrefix.IsEmpty())
    return ofn;

  PString fn = ofn;

  // add in suffix required for channel format, if any
  PINDEX pos = ofn.FindLast('.');
  if (pos == P_MAX_INDEX) {
    if (fn.Right(wavFilePrefix.GetLength()) != wavFilePrefix)
      fn += wavFilePrefix;
  }
  else {
    PString basename = ofn.Left(pos);
    PString ext      = ofn.Mid(pos+1);
    if (basename.Right(wavFilePrefix.GetLength()) != wavFilePrefix)
      basename += wavFilePrefix;
    fn = basename + "." + ext;
  }
  return fn;
}

PWAVFile * PVXMLChannel::CreateWAVFile(const PFilePath & fn, BOOL recording)
{ 
  PWAVFile * wav = PWAVFile::format(mediaFormat);
  if (wav == NULL) {
    PTRACE(1, "VXML\tWAV file format " << mediaFormat << " not known");
    return NULL;
  }

  wav->SetAutoconvert();
  if (!wav->Open(AdjustWavFilename(fn), 
                 recording ? PFile::WriteOnly : PFile::ReadOnly,
                 PFile::ModeDefault))
    PTRACE(1, "VXML\tCould not open WAV file " << wav->GetName());

  else if (recording) {
    wav->SetChannels(1);
    wav->SetSampleRate(8000);
    wav->SetSampleSize(16);
    return wav;
  } 
  
  else if (!wav->IsValid())
    PTRACE(1, "VXML\tWAV file header invalid for " << wav->GetName());

  else if (wav->GetSampleRate() != sampleFrequency)
    PTRACE(1, "VXML\tWAV file has unsupported sample frequency " << wav->GetSampleRate());

  else if (wav->GetChannels() != 1)
    PTRACE(1, "VXML\tWAV file has unsupported channel count " << wav->GetChannels());

  else {
    wav->SetAutoconvert();   /// enable autoconvert
    PTRACE(4, "VXML\tOpened WAV file " << wav->GetName());
    return wav;
  }

  delete wav;
  return NULL;
}


BOOL PVXMLChannel::Write(const void * buf, PINDEX len)
{
  if (closed)
    return FALSE;

  channelWriteMutex.Wait();

  // let the recordable do silence detection
  if (recordable != NULL && recordable->OnFrame(IsSilenceFrame(buf, len))) {
    PTRACE(1, "VXML\tRecording finished due to silence");
    EndRecording();
  }

  // if nothing is capturing incoming data, then fake the timing and return
  if ((recordable == NULL) && (GetBaseWriteChannel() == NULL)) {
    lastWriteCount = len;
    channelWriteMutex.Signal();
    PDelayChannel::Wait(len, nextWriteTick);
    return TRUE;
  }

  // write the data and do the correct delay
  if (!WriteFrame(buf, len)) 
    EndRecording();
  else
    totalData += lastWriteCount;

  channelWriteMutex.Signal();

  return TRUE;
}

BOOL PVXMLChannel::StartRecording(const PFilePath & fn, unsigned _finalSilence, unsigned _maxDuration)
{
  PVXMLRecordableFilename * recordable = new PVXMLRecordableFilename();
  if (!recordable->Open(fn)) {
    delete recordable;
    return FALSE;
  }

  recordable->SetFinalSilence(_finalSilence);
  recordable->SetMaxDuration(_maxDuration);
  return QueueRecordable(recordable);
}

BOOL PVXMLChannel::QueueRecordable(PVXMLRecordable * newItem)
{  
  totalData = 0;

  // shutdown any existing recording
  EndRecording();

  // insert the new recordable
  PWaitAndSignal mutex(channelWriteMutex);
  recordable = newItem;
  recording = TRUE;
  totalData = 0;
  newItem->OnStart();
  newItem->Record(*this);
  SetReadTimeout(frameDelay);
  return TRUE;
}


BOOL PVXMLChannel::EndRecording()
{
  PWaitAndSignal mutex(channelWriteMutex);

  if (recordable != NULL) {
    PTRACE(3, "PVXML\tFinished recording " << totalData << " bytes");

    PDelayChannel::Close();
    recordable->OnStop();
    delete recordable;
    recordable = NULL;
    PTRACE(3, "PVXML\tRecording finished");
  }

  return TRUE;
}

BOOL PVXMLChannel::Read(void * buffer, PINDEX amount)
{
  // assume we are returning silence
  BOOL silenceStuff = FALSE;
  BOOL delayDone = FALSE;

  {
    if (closed)
      return FALSE;

    PWaitAndSignal m(channelReadMutex);

    // if we are paused or in a delay, then do return silence
    if (paused || delayTimer.IsRunning())
      silenceStuff = TRUE;

    // if we are returning silence frames, then decrement the frame count
    // and contine returning silence
    else if (silentCount > 0) {
      silenceStuff = TRUE;
      silentCount--;
    }

    // if underlying channel is open, then read from the channel
    else if (GetBaseReadChannel() != NULL)
      silenceStuff = FALSE;

    // if underlying channel is not open, then see if there is anything in the queue
    else {
      PINDEX qSize;
      {
        PWaitAndSignal m(queueMutex);
        qSize = playQueue.GetSize();
      }

      // if nothing in queue, then return silence
      if (qSize == 0) 
        silenceStuff = TRUE;

      // otherwise queue the next data item
      else {
        {
          PWaitAndSignal m(queueMutex);
          PVXMLPlayable * qItem = (PVXMLPlayable *)playQueue.GetAt(0);
          qItem->OnStart();
          qItem->Play(*this);
          SetWriteTimeout(frameDelay);
        }
        silenceStuff = FALSE;
        totalData = 0;
        playing = TRUE;
      }
    }

    // if not doing silence, try and read more data
    // from the underlying channel

    if (!silenceStuff) {

      if (ReadFrame(buffer, amount)) {
        totalData += amount;
        delayDone = TRUE;
      } 

      else if (GetErrorCode(LastReadError) == Timeout)
        silenceStuff = TRUE;
    
      else {

        PTRACE(3, "PVXML\tFinished playing " << totalData << " bytes");
        PDelayChannel::Close();

        playing = FALSE;
        silenceStuff = TRUE;

        // get the item that was just playing
        PINDEX delay;
        {
          PWaitAndSignal m(queueMutex);
          PVXMLPlayable * qItem = (PVXMLPlayable *)playQueue.GetAt(0);
          if (qItem == NULL)
            delay = 0;
          else
            delay = qItem->GetDelay();

          // if the repeat count is non-zero, then repeat entry
          if (qItem->GetRepeat() > 1) {
            qItem->SetRepeat(qItem->GetRepeat()-1);
            qItem->OnRepeat(*this);
          } else {
            qItem->OnStop();
            delete playQueue.Dequeue();
          }
        }

        // if delay required, then setup the delay
        if (delay != 0) {
          PTRACE(3, "PVXML\tDelaying for " << delay);
          delayTimer = delay;
        }

        // if no delay, then check the queue size 
        else {
          PINDEX qSize;
          {
            PWaitAndSignal m(queueMutex);
            qSize = playQueue.GetSize();
          }
          // if nothing in the queue, trigger the main loop to perhaps send more data
          if (qSize == 0)
            vxmlInterface->Trigger();
        }
      }
    }
  }
  
  // start silence frame if required
  // note that this always requires a delay
  if (silenceStuff) {
    lastReadCount = CreateSilenceFrame(buffer, amount);
  }

  // make sure we always do the correct delay
  if (!delayDone)
    Wait(amount, nextReadTick);

  return TRUE;
}

BOOL PVXMLChannel::QueuePlayable(const PString & type,
                                 const PString & arg, 
                                 PINDEX repeat, 
                                 PINDEX delay, 
                                 BOOL autoDelete)
{
  PTRACE(3, "PVXML\tEnqueueing playable " << type << " with arg " << arg << " for playing");
  PVXMLPlayable * item = PFactory<PVXMLPlayable>::CreateInstance(type);
  if (item == NULL) {
    PTRACE(1, "VXML\tCannot find playable of type " << type);
    delete item;
    return FALSE;
  }

  if (!item->Open(*this, arg, delay, repeat, autoDelete)) {
    PTRACE(1, "VXML\tCannot open playable of type " << type << " with arg " << arg);
    delete item;
    return FALSE;
  }

  if (QueuePlayable(item))
    return TRUE;

  delete item;
  return FALSE;
}

BOOL PVXMLChannel::QueuePlayable(PVXMLPlayable * newItem)
{
  newItem->SetSampleFrequency(sampleFrequency);
  PWaitAndSignal mutex(queueMutex);
  playQueue.Enqueue(newItem);
  return TRUE;
}

BOOL PVXMLChannel::QueueResource(const PURL & url, PINDEX repeat, PINDEX delay)
{
  if (url.GetScheme() *= "file")
    return QueuePlayable("File", url.AsFilePath(), repeat, delay, FALSE);
  else
    return QueuePlayable("URL", url.AsString(), repeat, delay);
}

BOOL PVXMLChannel::QueueData(const PBYTEArray & data, PINDEX repeat, PINDEX delay)
{
  PTRACE(3, "PVXML\tEnqueueing " << data.GetSize() << " bytes for playing");
  PVXMLPlayableData * item = dynamic_cast<PVXMLPlayableData *>(PFactory<PVXMLPlayable>::CreateInstance("PCM Data"));
  if (item != NULL) {
    PTRACE(1, "VXML\tCannot find playable of type 'PCM Data'");
    delete item;
    return FALSE;
  }

  if (!item->Open(*this, "", delay, repeat, TRUE)) {
    PTRACE(1, "VXML\tCannot open playable of type 'PCM Data'");
    delete item;
    return FALSE;
  }

  if (QueuePlayable(item))
    return TRUE;

  delete item;
  return FALSE;
}

void PVXMLChannel::FlushQueue()
{
  PWaitAndSignal mutex(channelReadMutex);

  if (GetBaseReadChannel() != NULL)
    PDelayChannel::Close();

  PWaitAndSignal m(queueMutex);
  PVXMLPlayable * qItem;
  while ((qItem = playQueue.Dequeue()) != NULL)
    delete qItem;
}

///////////////////////////////////////////////////////////////

class PVXMLChannelPCM : public PVXMLChannel
{
  PCLASSINFO(PVXMLChannelPCM, PVXMLChannel);

  public:
    PVXMLChannelPCM();

  protected:
    // overrides from PVXMLChannel
    virtual BOOL WriteFrame(const void * buf, PINDEX len);
    virtual BOOL ReadFrame(void * buffer, PINDEX amount);
    virtual PINDEX CreateSilenceFrame(void * buffer, PINDEX amount);
    virtual BOOL IsSilenceFrame(const void * buf, PINDEX len) const;
    virtual void GetBeepData(PBYTEArray & data, unsigned ms);
};

PFactory<PVXMLChannel>::Worker<PVXMLChannelPCM> pcmVXMLChannelFactory(VXML_PCM16);

PVXMLChannelPCM::PVXMLChannelPCM()
  : PVXMLChannel(30, 480)
{
  mediaFormat    = VXML_PCM16;
  wavFilePrefix  = PString::Empty();
}

BOOL PVXMLChannelPCM::WriteFrame(const void * buf, PINDEX len)
{
  return PDelayChannel::Write(buf, len);
}

BOOL PVXMLChannelPCM::ReadFrame(void * buffer, PINDEX amount)
{
  PINDEX len = 0;
  while (len < amount)  {
    if (!PDelayChannel::Read(len + (char *)buffer, amount-len))
      return FALSE;

    len += GetLastReadCount();
  }

  return TRUE;
}

PINDEX PVXMLChannelPCM::CreateSilenceFrame(void * buffer, PINDEX amount)
{
  memset(buffer, 0, amount);
  return amount;
}

BOOL PVXMLChannelPCM::IsSilenceFrame(const void * buf, PINDEX len) const
{
  // Calculate the average signal level of this frame
  int sum = 0;

  const short * pcm = (const short *)buf;
  const short * end = pcm + len/2;
  while (pcm != end) {
    if (*pcm < 0)
      sum -= *pcm++;
    else
      sum += *pcm++;
  }

  // calc average
  unsigned level = sum / (len / 2);

  return level < 500; // arbitrary level
}

static short beepData[] = { 0, 18784, 30432, 30400, 18784, 0, -18784, -30432, -30400, -18784 };


void PVXMLChannelPCM::GetBeepData(PBYTEArray & data, unsigned ms)
{
  data.SetSize(0);
  while (data.GetSize() < (PINDEX)((ms * 8) / 2)) {
    PINDEX len = data.GetSize();
    data.SetSize(len + sizeof(beepData));
    memcpy(len + data.GetPointer(), beepData, sizeof(beepData));
  }
}

///////////////////////////////////////////////////////////////

class PVXMLChannelG7231 : public PVXMLChannel
{
  PCLASSINFO(PVXMLChannelG7231, PVXMLChannel);
  public:
    PVXMLChannelG7231();

    // overrides from PVXMLChannel
    virtual BOOL WriteFrame(const void * buf, PINDEX len);
    virtual BOOL ReadFrame(void * buffer, PINDEX amount);
    virtual PINDEX CreateSilenceFrame(void * buffer, PINDEX amount);
    virtual BOOL IsSilenceFrame(const void * buf, PINDEX len) const;
};

PFactory<PVXMLChannel>::Worker<PVXMLChannelG7231> g7231VXMLChannelFactory(VXML_G7231);

PVXMLChannelG7231::PVXMLChannelG7231()
  : PVXMLChannel(30, 0)
{
  mediaFormat     = VXML_G7231;
  wavFilePrefix  = "_g7231";
}

static const PINDEX g7231Lens[] = { 24, 20, 4, 1 };

BOOL PVXMLChannelG7231::WriteFrame(const void * buffer, PINDEX actualLen)
{
  PINDEX len = g7231Lens[(*(BYTE *)buffer)&3];
  if (len > actualLen)
    return FALSE;

  return PDelayChannel::Write(buffer, len);
}

BOOL PVXMLChannelG7231::ReadFrame(void * buffer, PINDEX /*amount*/)
{
  if (!PDelayChannel::Read(buffer, 1))
    return FALSE;

  PINDEX len = g7231Lens[(*(BYTE *)buffer)&3];
  if (len != 1) {
    if (!PIndirectChannel::Read(1+(BYTE *)buffer, len-1))
      return FALSE;
    lastReadCount++;
  } 

  return TRUE;
}

PINDEX PVXMLChannelG7231::CreateSilenceFrame(void * buffer, PINDEX /* len */)
{


  ((BYTE *)buffer)[0] = 2;
  memset(((BYTE *)buffer)+1, 0, 3);
  return 4;
}

BOOL PVXMLChannelG7231::IsSilenceFrame(const void * buf, PINDEX len) const
{
  if (len == 4)
    return TRUE;
  if (buf == NULL)
    return FALSE;
  return ((*(const BYTE *)buf)&3) == 2;
}

///////////////////////////////////////////////////////////////

class PVXMLChannelG729 : public PVXMLChannel
{
  PCLASSINFO(PVXMLChannelG729, PVXMLChannel);
  public:
    PVXMLChannelG729();

    // overrides from PVXMLChannel
    virtual BOOL WriteFrame(const void * buf, PINDEX len);
    virtual BOOL ReadFrame(void * buffer, PINDEX amount);
    virtual PINDEX CreateSilenceFrame(void * buffer, PINDEX amount);
    virtual BOOL IsSilenceFrame(const void * buf, PINDEX len) const;
};

PFactory<PVXMLChannel>::Worker<PVXMLChannelG729> g729VXMLChannelFactory(VXML_G729);

PVXMLChannelG729::PVXMLChannelG729()
  : PVXMLChannel(10, 0)
{
  mediaFormat    = VXML_G729;
  wavFilePrefix  = "_g729";
}

BOOL PVXMLChannelG729::WriteFrame(const void * buf, PINDEX /*len*/)
{
  return PDelayChannel::Write(buf, 10);
}

BOOL PVXMLChannelG729::ReadFrame(void * buffer, PINDEX /*amount*/)
{
  return PDelayChannel::Read(buffer, 10);
}

PINDEX PVXMLChannelG729::CreateSilenceFrame(void * buffer, PINDEX /* len */)
{
  memset(buffer, 0, 10);
  return 10;
}

BOOL PVXMLChannelG729::IsSilenceFrame(const void * /*buf*/, PINDEX /*len*/) const
{
  return FALSE;
}


#endif   // P_EXPAT

///////////////////////////////////////////////////////////////