A Beginners Tutorial
--------------------
$Revision$


- GET Queries

	The HttpRequest class can be used to execute any HTTP request method.
	The following example shows a simple GET request where a few query
	parameters are supplied.  Additionally potential cookies will be
	read from and written to a file.

<?php
$r = new HttpRequest('http://www.google.com');

// store Googles cookies in a dedicated file
$r->setOptions(
	array(	'cookiestore'	=> '../cookies/google.txt',
	)
);

$r->setQueryData(
	array(	'q'		=> '+"pecl_http" -msg -cvs -list',
			'hl'	=> 'de'
	)
);

// HttpRequest::send() returns an HttpMessage object
// of type HttpMessage::RESPONSE or throws an exception
try {
	print $r->send()->getBody();
} catch (HttpException $e) {
	print $e;
}
?>

- Multipart Posts

	The following example shows an multipart POST request, with two form
	fields and an image that's supposed to be uploaded to the server.
	It's a bad habit as well as common practice to issue a redirect after
	an received POST request, so we'll allow a redirect by enabling the
	redirect option.

<?php
$r = new HttpRequest('http://dev.iworks.at/.print_request.php', HTTP_POST);

// if redirects is set to true, a single redirect is allowed;
// one can set any reasonable count of allowed redirects
$r->setOptions(
	array(	'cookies'	=> array('MyCookie' => 'has a value'),
			'redirect'	=> true,
	)
);

// common form data
$r->setPostFields(
	array(	'name'	=> 'Mike',
			'mail'	=> 'mike@php.net',
	)
);
// add the file to post (form name, file name, file type)
$r->addPostFile('image', 'profile.jpg', 'image/jpeg');

try {
	print $r->send()->getBody();
} catch (HttpException $e) {
	print $e;
}
?>

- Parallel Requests

	It's possible to execute several HttpRequests in parallel with the
	HttpRequestPool class.  HttpRequests to send, do not need to perform
	the same request method, but can only be attached to one HttpRequestPool
	at the same time.

<?php
try {
	$p = new HttpRequestPool;
	// if you want to set _any_ options of the HttpRequest object,
	// you need to do so *prior attaching* to the request pool!
	$p->attach(new HttpRequest('http://pear.php.net', HTTP_HEAD));
	$p->attach(new HttpRequest('http://pecl.php.net', HTTP_HEAD));
} catch (HttpException $e) {
	print $e;
	exit;
}

try {
	$p->send();
	// HttpRequestPool implements an iterator over attached HttpRequest objects
	foreach ($p as $r) {
		print "Checking ", $r->getUrl(), " reported ", $r->getResponseCode(), "\n";
	}
} catch (HttpException $e) {
	print $e;
}
?>

- Parallel Requests?

	You can use a more advanced approach by using the protected interface of
	the HttpRequestPool class.  This allows you to perform some other tasks
	while the requests are executed.

<?php
class Pool extends HttpRequestPool
{
	public function __construct()
	{
		parent::__construct(
			new HttpRequest('http://pear.php.net', HTTP_HEAD),
			new HttpRequest('http://pecl.php.net', HTTP_HEAD)
		);

		// HttpRequestPool methods socketPerform() and socketSelect() are
		// protected;  one could use this approach to do something else
		// while the requests are being executed
		print "Executing requests";
		for ($i = 0; $this->socketPerform(); $i++) {
			$i % 3 or print ".";
			if (!$this->socketSelect()) {
				throw new HttpException("Socket error!");
			}
		}
		print "\nDone!\n";
	}
}

try {
	foreach (new Pool as $r) {
		print "Checking ", $r->getUrl(), " reported ", $r->getResponseCode(), "\n";
	}
} catch (HttpException $ex) {
	print $e;
}
?>

- Cached Responses

	One of the main key features of HttpResponse is HTTP caching.  HttpResponse
	will calculate an ETag based on the http.etag_mode INI setting as well as
	it will determine the last modification time of the sent entity.  It uses
	those two indicators to decide if the cache entry on the client side is
	still valid and will emit an "304 Not Modified" response if applicable.

<?php
HttpResponse::setCacheControl('public');
HttpResponse::setCache(true);
HttpResponse::capture();

print "This will be cached until content changes!\n";
print "Note that this approach will only save the clients download time.\n";
?>

- Bandwidth Throttling

	HttpResponse supports a basic throttling mechanism, which is enabled by
	setting a throttle delay and a buffer size.  PHP will sleep the specified
	amount of seconds after each sent chunk of specified bytes.

<?php
// send 5000 bytes every 0.2 seconds, i.e. max ~25kByte/s
HttpResponse::setThrottleDelay(0.2);
HttpResponse::setBufferSize(5000);
HttpResponse::setCache(true);
HttpResponse::setContentType('application/x-zip');
HttpResponse::setFile('../archive.zip');
HttpResponse::send();
?>

Exemplar Use Cases
------------------

- KISS XMLRPC Client

<?php
class XmlRpcClient
{
	public $namespace;
	protected $request;

	public function __construct($url, $namespace = '')
	{
		$this->namespace = $namespace;
		$this->request = new HttpRequest($url, HTTP_POST);
		$this->request->setContentType('text/xml');
	}

	public function setOptions($options = array())
	{
		return $this->request->setOptions($options);
	}

	public function addOptions($options)
	{
		return $this->request->addOptions($options);
	}

	public function __call($method, $params)
	{
		if ($this->namespace) {
			$method = $this->namespace .'.'. $method;
		}
		$this->request->setPostData(xmlrpc_encode_request($method, $params));
		$response = $this->request->send();
		if ($response->getResponseCode() != 200) {
			throw new Exception($response->getBody(), $response->getResponseCode());
		}
		return xmlrpc_decode($response->getBody(), 'utf-8');
	}
	
	public function getHistory()
	{
		return $this->request->getHistory();
	}
}

?>

- Simple Feed Aggregator

<?php
class FeedAggregator
{
	public $directory;
	protected $feeds = array();

	public function __construct($directory = 'feeds')
	{
		$this->setDirectory($directory);
	}

	public function setDirectory($directory)
	{
		$this->directory = $directory;
		foreach (glob($this->directory .'/*.xml') as $feed) {
			$this->feeds[basename($feed, '.xml')] = filemtime($feed);
		}
	}

	public function url2name($url)
	{
		return preg_replace('/[^\w\.-]+/', '_', $url);
	}
	
	public function hasFeed($url)
	{
		return isset($this->feeds[$this->url2name($url)]);
	}

	public function addFeed($url)
	{
		$r = $this->setupRequest($url);
		$r->send();
		$this->handleResponse($r);
	}

	public function addFeeds($urls)
	{
		$pool = new HttpRequestPool;
		foreach ($urls as $url) {
			$pool->attach($this->setupRequest($url));
		}
		$pool->send();

		foreach ($pool as $request) {
			$this->handleResponse($request);
		}
	}

	public function getFeed($url)
	{
		$this->addFeed($url);
		return $this->loadFeed($this->url2name($url));
	}

	public function getFeeds($urls)
	{
		$feeds = array();
		$this->addFeeds($urls);
		foreach ($urls as $url) {
			$feeds[] = $this->loadFeed($this->url2name($url));
		}
		return $feeds;
	}

	protected function saveFeed($file, $contents)
	{
		if (file_put_contents($this->directory .'/'. $file .'.xml', $contents)) {
			$this->feeds[$file] = time();
		} else {
			throw new Exception("Could not save feed contents to $file.xml");
		}
	}

	protected function loadFeed($file)
	{
		if (isset($this->feeds[$file]) {
			if ($data = file_get_contents($this->directory .'/'. $file .'.xml')) {
				return $data;
			} else {
				throw new Exception("Could not load feed contents from $file.xml");
			}
		} else {
			throw new Exception("Unknown feed/file $file.xml");
		}
	}

	protected function setupRequest($url)
	{
		$r = new HttpRequest($url);
		$r->setOptions(array('redirect' => true));

		$file = $this->url2name($url);

		if (isset($this->feeds[$file])) {
			$r->addOptions(array('lastmodified' => $this->feeds[$file]));
		}

		return $r;
	}

	protected function handleResponse(HttpRequest $r)
	{
		if ($r->getResponseCode() != 304) {
			if ($r->getResponseCode() != 200) {
				throw new Exception("Unexpected response code ". $r->getResponseCode());
			}
			if (!strlen($body = $r->getResponseBody())) {
				throw new Exception("Received empty feed from ". $r->getUrl());
			}
			$this->saveFeed($file, $body);
		}
	}
}
?>