convert php code into .net 2.0 of chat application

Question

hello sir,
can u plz help me its very urgent for me.....
i want to add chat facility in my project web site which is in asp.net 2.0 with c#.
one chat application i downloaded which is in php, i try to convert this but not converted its connection code.
the code is :
<?php
define ('DBPATH','localhost');
define ('DBUSER','root');
define ('DBPASS','password');
define ('DBNAME','chat');
session_start();
global $dbh;
$dbh = mysql_connect(DBPATH,DBUSER,DBPASS);
mysql_selectdb(DBNAME,$dbh);
if ($_GET['action'] == "chatheartbeat") { chatHeartbeat(); }
if ($_GET['action'] == "sendchat") { sendChat(); }
if ($_GET['action'] == "closechat") { closeChat(); }
if ($_GET['action'] == "startchatsession") { startChatSession(); }
if (!isset($_SESSION['chatHistory'])) {
 $_SESSION['chatHistory'] = array(); 
}
if (!isset($_SESSION['openChatBoxes'])) {
 $_SESSION['openChatBoxes'] = array(); 
}
function chatHeartbeat() {
 
 $sql = "select * from chat where (chat.to = '".mysql_real_escape_string($_SESSION['username'])."' AND recd = 0) order by id ASC";
 $query = mysql_query($sql);
 $items = '';
 $chatBoxes = array();
 while ($chat = mysql_fetch_array($query)) {
  if (!isset($_SESSION['openChatBoxes'][$chat['from']]) && isset($_SESSION['chatHistory'][$chat['from']])) {
   $items = $_SESSION['chatHistory'][$chat['from']];
  }
  $chat['message'] = sanitize($chat['message']);
  $items .= <<<EOD
        {
   "s": "0",
   "f": "{$chat['from']}",
   "m": "{$chat['message']}"
    },
EOD;
 if (!isset($_SESSION['chatHistory'][$chat['from']])) {
  $_SESSION['chatHistory'][$chat['from']] = '';
 }
 $_SESSION['chatHistory'][$chat['from']] .= <<<EOD
         {
   "s": "0",
   "f": "{$chat['from']}",
   "m": "{$chat['message']}"
    },
EOD;
  
  unset($_SESSION['tsChatBoxes'][$chat['from']]);
  $_SESSION['openChatBoxes'][$chat['from']] = $chat['sent'];
 }
 if (!empty($_SESSION['openChatBoxes'])) {
 foreach ($_SESSION['openChatBoxes'] as $chatbox => $time) {
  if (!isset($_SESSION['tsChatBoxes'][$chatbox])) {
   $now = time()-strtotime($time);
   $time = date('g:iA M dS', strtotime($time));
   $message = "Sent at $time";
   if ($now > 180) {
    $items .= <<<EOD
{
"s": "2",
"f": "$chatbox",
"m": "{$message}"
},
EOD;
 if (!isset($_SESSION['chatHistory'][$chatbox])) {
  $_SESSION['chatHistory'][$chatbox] = '';
 }
 $_SESSION['chatHistory'][$chatbox] .= <<<EOD
  {
"s": "2",
"f": "$chatbox",
"m": "{$message}"
},
EOD;
   $_SESSION['tsChatBoxes'][$chatbox] = 1;
  }
  }
 }
}
 $sql = "update chat set recd = 1 where chat.to = '".mysql_real_escape_string($_SESSION['username'])."' and recd = 0";
 $query = mysql_query($sql);
 if ($items != '') {
  $items = substr($items, 0, -1);
 }
header('Content-type: application/json');
?>
{
  "items": [
   <?php echo $items;?>
        ]
}
<?php
   exit(0);
}
function chatBoxSession($chatbox) {
 
 $items = '';
 
 if (isset($_SESSION['chatHistory'][$chatbox])) {
  $items = $_SESSION['chatHistory'][$chatbox];
 }
 return $items;
}
function startChatSession() {
 $items = '';
 if (!empty($_SESSION['openChatBoxes'])) {
  foreach ($_SESSION['openChatBoxes'] as $chatbox => $void) {
   $items .= chatBoxSession($chatbox);
  }
 }

 if ($items != '') {
  $items = substr($items, 0, -1);
 }
header('Content-type: application/json');
?>
{
  "username": "<?php echo $_SESSION['username'];?>",
  "items": [
   <?php echo $items;?>
        ]
}
<?php

 exit(0);
}
function sendChat() {
 $from = $_SESSION['username'];
 $to = $_POST['to'];
 $message = $_POST['message'];
 $_SESSION['openChatBoxes'][$_POST['to']] = date('Y-m-d H:i:s', time());
 
 $messagesan = sanitize($message);
 if (!isset($_SESSION['chatHistory'][$_POST['to']])) {
  $_SESSION['chatHistory'][$_POST['to']] = '';
 }
 $_SESSION['chatHistory'][$_POST['to']] .= <<<EOD
        {
   "s": "1",
   "f": "{$to}",
   "m": "{$messagesan}"
    },
EOD;

 unset($_SESSION['tsChatBoxes'][$_POST['to']]);
 $sql = "insert into chat (chat.from,chat.to,message,sent) values ('".mysql_real_escape_string($from)."', '".mysql_real_escape_string($to)."','".mysql_real_escape_string($message)."',NOW())";
 $query = mysql_query($sql);
 echo "1";
 exit(0);
}
function closeChat() {
 unset($_SESSION['openChatBoxes'][$_POST['chatbox']]);
 
 echo "1";
 exit(0);
}
function sanitize($text) {
 $text = htmlspecialchars($text, ENT_QUOTES);
 $text = str_replace("\n\r","\n",$text);
 $text = str_replace("\r\n","\n",$text);
 $text = str_replace("\n","<br>",$text);
 return $text;
}
 
this code i downloaded from this site : http://anantgarg.com/2009/05/13/gmail-facebook-style-jquery-chat/
plz sir help becoz its very urgent for me.... send me solution on my email id [email protected]
thank you sir....