I did something similar not too long ago. I wrote a function that logs the progress to a text file as a JSON object. Then I wrote a PHP function that returns that JSON object to the browser at certain intervals as requested by jQuery.
My PHP code looks similar to this:
function logProgress($task, $status, $progress) {
$basedir = "/var/www/" . SITE_ROOT . "/";
$log_file = $basedir . "logs/progress.log";
$logFileContent = file_get_contents($mrp_log_file);
if($logFileContent){
$logFileArray = json_decode($logFileContent, TRUE);
} else {
$logFileArray = array();
}
$logFileArray[$task]=array('task'=>$task,'status'=>$status,'progress'=>$progress);
$logFile = fopen($log_file, 'w+') or error_log("Failed to open progress file $mrp_log_file for writing");
fwrite($logFile, json_encode($logFileArray));
fclose($logFile);
}
Retrieving the data is as simple as this:
function readProgressLog() {
//Returns a JSON object stored in the progress log.
$basedir = "/var/www/" . SITE_ROOT . "/";
$log_file = $basedir . "logs/progress.log";
$logFileContents = file_get_contents($log_file);
return $logFileContents;
}
From jQuery, you would make two AJAX calls, one to initiate your process, and one to poll the text file. My javascript for the polling call looks like this:
function updateProgress() {
var data = {
action:'getProgressUpdate'};
var settings = {success: function(json){
var done = false;
if(json!=null) {
//Put your code to update the progress bar here.
//I look for a JSON property called Done to flag the process as completed.
if(json.Done==null) {
var t2 = setTimeout("updateProgress()", 1000);
} else {
clearTimeout(t2);
done = true;
clearProgressLog();
}
} else {
var t2 = setTimeout("updateProgress()", 1000);
}
},
data:data,
cache:false,
type: 'POST',
dataType:"json"};
$.ajax('/ajax/polling.ajax.php', settings);
}
One thing I noticed is that you should make sure your polling AJAX call uses a different PHP file than your process AJAX call, otherwise your polling call won't finish until the process call is finished.