HTTP_Request_Listener
Introduction to HTTP_Request_Listener
HTTP_Request_Listener is an abstract class that can be extended to capture events and respond to them as they occur. Included with HTTP_Request is an example of a console-based progress bar. To implement this, the HTTP_Request_DownloadListener class is used, which uses the Console_ProgressBar package to display a download progress meter.
Example usage of HTTP_Request_Listener
In order to use a listener, it must attach to the specific HTTP_Request or HTTP_Response object that you want to monitor. The attach code is shown at the bottom of the example. As you can see, the event listener is propagated from the HTTP_Request object to any child HTTP_Response objects, and attaching only need happen to the first HTTP_Request object.
Download progress bar with HTTP_Request_Listener
<?php
/**
* An example of Listener usage with HTTP_Request. This downloads and saves
* the file displaying the progress bar in the process.
*
* Note two things:
* 1) The file should be run in console, not in browser;
* 2) You should turn output buffering OFF for this to work properly.
*/
require_once 'HTTP/Request.php';
require_once 'HTTP/Request/Listener.php';
require_once 'Console/ProgressBar.php';
PEAR::setErrorHandling(PEAR_ERROR_DIE);
set_time_limit(0);
class HTTP_Request_DownloadListener extends HTTP_Request_Listener
{
/**
* Handle for the target file
* @var int
*/
var $_fp;
/**
* Console_ProgressBar intance used to display the indicator
* @var object
*/
var $_bar;
/**
* Name of the target file
* @var string
*/
var $_target;
/**
* Number of bytes received so far
* @var int
*/
var $_size = 0;
function HTTP_Request_DownloadListener()
{
$this->HTTP_Request_Listener();
}
/**
* Opens the target file
* @param string Target file name
* @throws PEAR_Error
*/
function setTarget($target)
{
$this->_target = $target;
$this->_fp = @fopen($target, 'wb');
if (!$this->_fp) {
PEAR::raiseError("Cannot open '{$target}'");
}
}
function update(&$subject, $event, $data = null)
{
switch ($event) {
case 'sentRequest':
$this->_target = basename($subject->_url->path);
break;
case 'gotHeaders':
if (isset($data['content-disposition']) &&
preg_match('/filename="([^"]+)"/', $data['content-disposition'], $matches)) {
$this->setTarget(basename($matches[1]));
} else {
$this->setTarget($this->_target);
}
$this->_bar =& new Console_ProgressBar(
'* ' . $this->_target . ' %fraction% KB [%bar%] %percent%', '=>', '-',
79, (isset($data['content-length'])? round($data['content-length'] / 1024): 100)
);
$this->_size = 0;
break;
case 'tick':
$this->_size += strlen($data);
$this->_bar->update(round($this->_size / 1024));
fwrite($this->_fp, $data);
break;
case 'gotBody':
fclose($this->_fp);
break;
case 'connect':
case 'disconnect':
break;
default:
PEAR::raiseError("Unhandled event '{$event}'");
} // switch
}
}
// Try using any other package if you like, but choose the bigger ones
// to be able to see the progress bar
$url = 'http://pear.php.net/get/HTML_QuickForm-stable';
$req =& new HTTP_Request($url);
$download =& new HTTP_Request_DownloadListener();
$req->attach($download);
$req->sendRequest(false);
?>
Events that can be caught
The HTTP_Request class sends these events:
-
connect- upon server connection, this event is sent -
sentRequest- after the request was sent, this event is sent -
disconnect- after server disconnect, this event is sent
The HTTP_Response class sends these events:
-
gotHeaders- this event is sent after receiving response headers (headers are passed in $data as an associative array) -
tick- this event is sent on receiving a part of response body (the part is passed in $data as a string) -
gzTick- this event is sent on receiving a part of response body that is gzip-compressed (the part is passed in $data as a string) -
gotBody- this event is sent on after receiving the complete response body (the decoded body is passed as a string in $data if it was gzipped)