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+--- Thread: Server Sent Events With Codeigniter 4 (/showthread.php?tid=78263)
Server Sent Events With Codeigniter 4 - midhunlalkc - 12-24-2020
I am trying to update the progress of a long running php script on frontend using server sent events.
But am only receiving first few eventstreams and thereafter there is error. I am Sharing code below;
Html View:
Code:
<a href="#" onclick="startScraping()" >START SCRAPING</a>
<a href="#" onclick="stopScraping()" >STOP SCRAPING</a>
<script>
var source = 'THE SOURCE';
function startScraping()
{
if(typeof(EventSource) !== "undefined") {
source = new EventSource('<?= route_to('start-scraping') ?>');
source.addEventListener('message' , function(e)
{
var result = JSON.parse( e.data );
addLog(result.message);
var el = document.getElementById('progressBar');
el.style.width = result.progress + '%';
el.setAttribute('aria-valuenow', result.progress);
if(e.data.search('TERMINATE') != -1)
{
addLog('Received TERMINATE closing');
source.close();
}
});
source.addEventListener('error' , function(e)
{
addLog('eventSource: error occurred');
if (this.readyState == EventSource.CONNECTING) {
console.log('eventSource: reconnecting (readyState=${this.readyState})...');
} else {
console.log("eventSource: connection failed");
}
source.close();
});
} else {
document.getElementById("result").innerHTML = "Sorry, your browser does not support server-sent events...";
}
}
function stopScraping()
{
source.close();
addLog('Interrupted');
}
function addLog(message)
{
var r = document.getElementById('results');
r.innerHTML += message + '<br>';
r.scrollTop = r.scrollHeight;
}
</script>Home Controller:
PHP Code:
<?php namespace App\Controllers;
class Home extends BaseController
{
public function __construct(){}
/**
* Function to start web scraping
*/
public function startScraping()
{
header("Content-Type: text/event-stream");
header("Cache-Control: no-cache");
while (ob_get_level() > 0) {
ob_end_flush();
}
ini_set('max_execution_time', 0);
$serverTime = time();
for ($i=1; $i < 10000 ; $i++) {
$percent = intval(($i/10000) * 100);
sendMsg($serverTime, $i.' row(s) Processed.' , $percent);
sleep(1);
}
sendMsg($serverTime, 'TERMINATE',100);
flush();
exit;
}
}
Common.php file:
PHP Code:
function sendMsg($id, $message, $progress)
{
$d = array('message' => $message, 'progress' => $progress);
echo "id:". $id . PHP_EOL;
echo "data:". json_encode($d) . PHP_EOL;
echo PHP_EOL;
ob_end_flush();
flush();
}
Here this loop is not fully executed. I am only receiving first few rows as response. There after am getting this error
id:1608816937
data:{"message":"1 row(s) Processed.","progress":0}
<br />
<b>Fatal error</b>: Uncaught ErrorException: Cannot modify header information - headers already sent by (output started at /var/www/webScraper/app/Common.php:130) in /var/www/webScraper/system/Debug/Exceptions.php:164
Stack trace:
#0 [internal function]: CodeIgniter\Debug\Exceptions->errorHandler(2, 'Cannot modify h...', '/var/www/webScr...', 164, Array)
#1 /var/www/webScraper/system/Debug/Exceptions.php(164): header('HTTP/1.1 500 In...', true, 500)
#2 [internal function]: CodeIgniter\Debug\Exceptions->exceptionHandler(Object(ErrorException))
#3 {main}
thrown in <b>/var/www/webScraper/system/Debug/Exceptions.php</b> on line <b>164</b><br />
<br />
<b>Fatal error</b>: Uncaught ErrorException: Cannot modify header information - headers already sent by (output started at /var/www/webScraper/app/Common.php:130) in /var/www/webScraper/system/Debug/Exceptions.php:164
Stack trace:
#0 [internal function]: CodeIgniter\Debug\Exceptions->errorHandler(2, 'Cannot modify h...', '/var/www/webScr...', 164, Array)
#1 /var/www/webScraper/system/Debug/Exceptions.php(164): header('HTTP/1.1 500 In...', true, 500)
#2 /var/www/webScraper/system/Debug/Exceptions.php(224): CodeIgniter\Debug\Exceptions->exceptionHandler(Object(ErrorException))
#3 [internal function]: CodeIgniter\Debug\Exceptions->shutdownHandler()
#4 {main}
thrown in <b>/var/www/webScraper/system/Debug/Exceptions.php</b> on line <b>164</b><br />
What am i doing wrong?
RE: Server Sent Events With Codeigniter 4 - InsiteFX - 12-24-2020
Sounds like your re-sending the headers again hard to tell by the code fragments.
Check your headers they should only be sent once.
RE: Server Sent Events With Codeigniter 4 - includebeer - 12-24-2020
PHP Code:
headers already sent by (output started at /var/www/webScraper/app/Common.php:130)
Often the error for header already sent means there’s an error message that was printed.
What do you have on line 130?
RE: Server Sent Events With Codeigniter 4 - midhunlalkc - 12-25-2020
(12-24-2020, 01:30 PM)includebeer Wrote:PHP Code:headers already sent by (output started at /var/www/webScraper/app/Common.php:130)
Often the error for header already sent means there’s an error message that was printed.
What do you have on line 130?
echo "id:". $id . PHP_EOL;
this is the code i have on line 130 on common.php file. complete function is as below
PHP Code:
function sendMsg($id, $message, $progress)
{
$d = array('message' => $message, 'progress' => $progress);
echo "id:". $id . PHP_EOL; // Line number 130
echo "data:". json_encode($d) . PHP_EOL;
echo PHP_EOL;
//PUSH THE data out by all FORCE POSSIBLE
ob_end_flush();
flush();
}