Progressive display - UK Web Hosting | Dedicated Server Windows and Linux VPS Forum

**Coomkeen** · #1 (**permalink**) 12-01-2008, 11:00

Now I'm baffled.

How come, when you have a slow connection say, or the server is rather busy, that some sites display part of the page, then another bit, and then more, until it's finished?

But when I try:

<html>
<head>
</head>
<body>
Test<br>
</body>
</html>
<?php
$i=1;
while($i <= 5){
echo("Wait " . $i . "<br>");
sleep(1);
$i++;
}
?>

Nothing happens until the whole page processing has finished.
And then it displays the php bit, apparently taking no notice of the </html> etc.

Any idea what's going on here?

Ron

**Rock** · #2 (**permalink**) 12-01-2008, 23:33

Hello Ron, Where are you running this PHP from ? I've had this tested on most our servers [Windows & Linux] & it worked well for me. When run, it started to process the whole page along with the PHP inside, starting from test :

Quote:

Test
Wait 1
Wait 2
Wait 3
Wait 4
Wait 5

Once it was done, the page stopped loading. I doubt this being a network latency issue, hence the timeout on your end.
Please email our support dept, with your complete details, in case you face any similar issue on your account hosted with us, we'd get this fixed for you.

**Coomkeen** · #3 (**permalink**) 13-01-2008, 07:25

Hello Rock,

Yes it works OK. No problem there.
But what puzzles me is why, when the </html> is met by the browser, it still continues to obey the other html commands.
As far as the browser is concerned the </html> seems to have no significance.

Does Apache feed out the file contents, and php generated html, bit by bit, or does it wait until it's finished all the processing before sending the whole thing?

Ultimately, what I'm after, is to be able to display an html page on the browser, and still let the server php continue processing a long job.
This would enable the user to, say, click a link to go away from the page, but still leave the php on that page processing.

As it stands, it seems that the html in the file only appears on the browser after all php processing has finished.

Ron.

**mephisto** · #4 (**permalink**) 19-01-2008, 20:50

I think your talking about flushing the current output to the browser, you need to use output buffering and then flush it to the browser.

eg.

PHP Code:


			
<?

if (ob_get_level() == 0) ob_start();

for($i = 0; $i < 10; $i++) {

    echo "<br/>$i";  // your output

 

    ob_flush();

    flush();  // needed ob_flush

    usleep(50000);// delay minimum of .05 seconds to allow ie to flush to screen

}

?>

**Coomkeen** · #5 (**permalink**) 19-01-2008, 20:57

Ah yes that's it.
Many thanks Mephisto.

Apache seems to be set to send at 4096 as default.
So forcing a flush is the thing.

Thanks again.

Ron