automatically update xml feed from mysql db without refresh the page

Question

I have to develop one xml feed from mysql database using php code..here i have to insert or update any data on my mysql database means that inserted and updated data automatically change and insert on my xml feed also without refresh the page.how can i develop this.please help me.

i have used below code:

$catname=func_query_first_cell("select status from $sql_tbl[orders] where status='Q'");
     $file= fopen("orderdetails1.xml", "w");        
     $_xml ="<?xml version=\"1.0\" encoding=\"ISO-8859-1\" ?>\r\n"; 
     $_xml .="\t<Feed>\r\n";
     $_xml .="\t<order>\r\n";

$_xml .="\t<status>" .htmlspecialchars($catname,ENT_QUOTES). "</status>\r\n";   
$page = (int) (!isset($_GET["page"]) ? 1 : $_GET["page"]);
$limit = 2;
$startpoint = ($page * $limit) - $limit;
$statement = "`xcart_orders` where `active` = 1";    
$counterr=0;
$r=func_query("select * from $sql_tbl[orders] LIMIT {$startpoint}, {$limit}");
foreach($r as $n)
 {
$products=func_query_first("select * from $sql_tbl[orders] where status='Q'");
 $products=func_query_first("select product from $sql_tbl[order_details] where orderid=$n[orderid]");

$infeed_counter++;

 echo $manufacturer."=====";

if($row[avail]>0)
                $avail='Y'; 
            else 
                $avail='N'; 


$_xml .="\t<Order>\r\n";
  $_xml .="\t<orderid>" .$n[orderid]. "</orderid>\r\n";
   $_xml .="\t<login>" .  htmlspecialchars(strip_tags(substr($n[login],0,50)) , ENT_QUOTES ). "</login>\r\n";   
$_xml .="\t<total>" . $n[total]. "</total>\r\n";
    $_xml .="\t<product>" .  $products[product]. "</product>\r\n";
    $_xml .="\t</Order>\r\n";   
}

    $_xml .="\t</order>\r\n";   
    $_xml .="\t</Feed>\r\n";    
fwrite($file, $_xml);       
 fclose($file);     
echo "XML version of products available here with $infeed_counter products.  <a href=\"orderdetails1.xml?page=$page\">View the XML.</a>";
     exit;
     ?>

Now i got the below xml feed:

<Feed>
<order>
<status>Q</status>
<Order>
   <orderid>1</orderid>
        <login>krishna</login>
        <total>399.99</total>
        <product>Designing Web Usability</product>
</Order>
 <Order>
        <orderid>65</orderid>
        <login>krishna</login>
        <total>399.99</total>
        <product>Three Stone Princess Cut Diamond Ring</product>
  </Order>
 <Order>
          <orderid>2</orderid>
          <login>krishna</login>
          <total>34.65</total>
           <product>Three Stone Princess Cut Diamond Ring</product>
</Order>

Now i wish to change the total 399.99 to 500.00 for orderid=1 on my mysql database means have to refresh the page.then only my xml feed is changed here.but i wish to need the solution is the database change is automatically update on my xml feed without refresh the page.please help me.how can i develop this.

Answer 1

Try like this: feed.php

$catname = func_query_first_cell("select status from $sql_tbl[orders] where status='Q'");
$file = fopen("orderdetails1.xml", "w");
$_xml = "<?xml version=\"1.0\" encoding=\"ISO-8859-1\" ?>";
$_xml .= "<Feed>";
$_xml .= "<order>";

$_xml .= "<status>" . htmlspecialchars($catname, ENT_QUOTES) . "</status>";
$page = (int)(!isset($_GET["page"]) ? 1 : $_GET["page"]);
$limit = 2;
$startpoint = ($page * $limit) - $limit;
$statement = "`xcart_orders` where `active` = 1";
$counterr = 0;
$r = func_query("select * from $sql_tbl[orders] LIMIT {$startpoint}, {$limit}");
foreach ($r as $n)
{
    $products = func_query_first("select * from $sql_tbl[orders] where status='Q'");
    $products = func_query_first("select product from $sql_tbl[order_details] where orderid=$n[orderid]");

    $infeed_counter++;

    // echo $manufacturer."=====";

    if ($row[avail] > 0)
        $avail = 'Y';
    else
        $avail = 'N';


    $_xml .= "<Order>";
    $_xml .= "<orderid>" . $n[orderid] . "</orderid>";
    $_xml .= "<login>" . htmlspecialchars(strip_tags(substr($n[login], 0, 50)), ENT_QUOTES) . "</login>";
    $_xml .= "<total>" . $n[total] . "</total>";
    $_xml .= "<product>" . $products[product] . "</product>";
    $_xml .= "</Order>";
}

$_xml .= "</order>";
$_xml .= "</Feed>";

header ("Content-Type:text/xml"); 
echo $_xml;

in the XML feed URL access like this:

http://www.exampleyourdoamin/feed.php

Answer 2

You need to use a technique called long polling. Long polling keeps a connection open for certain amount of time. During this time it checks if there is any change in database. If yes, it breaks the connection and sends those changes to frontend. And then immediately starts another connection. You will find more information here. http://techoctave.com/c7/posts/60-simple-long-polling-example-with-javascript-and-jquery