Tag Archives: Technology/Internet

Download Images with PHP

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As it seems one possible solution while trying to download images with PHP is to write a “client” to do so. Will it be with cURL, Zend Framework or some other tool – it doesn’t matter.

However one of the most used approaches is simply with file_get_contents and file_put_contents. I’m not sure whether I wrote already about this or not, but this solution simply looks something like this.

 
file_put_contents('/path/to/file', 
                  file_get_contents('http://www.example.com/source.image');

In fact a client will give you more control over the process, to handle errors, etc. So maybe this is a better solution.

A Memcached Zend_Cache

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Zend_Cache

Usually Zend_Cache is used to store cache files on the file system, which can be really fast and useful in most of the cases. However there’s a faster cache mechanism and hopefully it’s supported by Zend_Cache as well. This is the Memcached backend.

A Faster Cache

Memcached is a really powerful tool to cache directly into the RAM. First, this tool has nothing to do primary with Zend Framework. It’s a server, usually started on some port, that can be called to store and get things from the memory. This of course is very fast, way faster than the cache in the hard drives.

Zend_Cache and Memcached

Zend_Cache has an interface to work with Memcached which is great as usual. The PHP example of Memcache (note that there are two things Memcache and Memcached, which are slight different) can be found here and as it says:

$memcache = new Memcache;
$memcache->connect('localhost', 11211) or die ("Could not connect");
 
$version = $memcache->getVersion();
echo "Server's version: ".$version."<br/>\n";
 
$tmp_object = new stdClass;
$tmp_object->str_attr = 'test';
$tmp_object->int_attr = 123;
 
$memcache->set('key', $tmp_object, false, 10) or die ("Failed to save data at the server");
echo "Store data in the cache (data will expire in 10 seconds)<br/>\n";
 
$get_result = $memcache->get('key');
echo "Data from the cache:<br/>\n";
 
var_dump($get_result);

However this can be coded into a Zend Framework style like that:

$frontend = array('caching' => true, 'lifetime' => 1800, 'automatic_serialization' => true);
 
$backend = array(
    'servers' =>array(
        array('host' => '127.0.0.1', 'port' => 11211)
    ),
    'compression' => false
);
 
$cache = Zend_Cache::factory('Core', 'Memcached', $frontend, $backend);

Note that you don’t have the typical “cache_dir”, just because everything’s cached into the memory.

Now you can call the cache as it’s called with the “File” backend interface:

$key = 'mykey';
 
if (($result = $cache->load($key)) === false) {
	// call the slow database query here ...
	// save in $result
 
	$cache->save($result, $key);	
}
 
echo $result

More on CSS Optimization

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As CSS files are first downloaded to the client and then executed, the main optimization is to make those files smaller. But that doesn’t mean only minifing!

CSS

The Minification Process

While with minification you can strip all the symbols that only take space, but are useless when the browser parses the file, there are some other techniques, which in fact aren’t so simple, to speed up the loading process. By minification you get rid of the white spaces, tabs, new lines, etc., but the file may remain too large.

Useless Rules

Yes, sadly the browser doesn’t need all those white spaces, actually web developers need them. Just because this makes the file more readable, or readable at all. However most of the web applications have one large CSS file, typically named layout.css, main.css or whatever, that contains all the rules for the entire application. In many of the cases one page of a site doesn’t need all the rules for the site, so a possible solution is to remove all of the rules that aren’t used.

There are tools that may help you do the job. Such a tool, that I’m using is the Firefox add-on – Dust-Me Selectors. Of course there are a lot other tools doing the same job, so it’s up to you to pick up one.

After removing all those useless rules you’ll see that the size of the file can be something like 20% of the size of the source file. This is interesting to note, because most of the time the minification cannot give you such performance benefit. In fact this comes with some issues.

One Request or What?

This is the dilemma of the web programming, isn’t it? However thus you can split the main CSS file to few smaller files, but they are named differently so you cannot expect the browser to cache them when the user visits the site for the first time.

The case must be, of course, tested against various situations, so you can decide what suits you. However the typical scenario is to optimize only few of the pages, as they might be the most visited – as for example the homepage. If two of the pages are mainly visited, than you can make custom, small, CSS files for them with only the necessary rules, and let the other pages with the main CSS file. If you’ve a lot of returning visitors, you can be sure the custom files will be cached (if the client cache is turned on) and the second time somebody visits the “homepage” for example the page will load faster.

Diving into Node.js – A Long Polling Example

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Node.js vs. The World

What is typical for most of the web servers is that they listen for requests and respond as quickly as possible on every one of them. In fact the speed of the response is one of the main targets of optimization for developers. Fast servers are what everyone needs. From web developers to website visitors!

In the field of the that battle different web servers have different “weapons” to gain time. While this is useful in most of the cases, when it comes to a chat-like applications and Node.js approaches, the response is not always immediately returned. As I described in my posts until now about Node.js, a simple web server may wait for an event to be emitted, and than return the response. Continue reading Diving into Node.js – A Long Polling Example →

Diving into Node.js – Very First App

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What do I have till now?

After Node.js is istalled, described in my previous post, I can simply run this command:

stoimenpopov:~# node server.js

and this will start the server with the code within server.js. But what’s the code of server.js?

Following the instructions of Node’s homepage and most of the tutorials I’ve found, I can simply copy/paste the code from the first lines of Node’s page:

var http = require('http');
http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World\n');
}).listen(8124, "127.0.0.1");
console.log('Server running at http://127.0.0.1:8124/');

There are several things I find interesting in this code, making it different from JavaScript as we know it. First of all what is

var http = require(‘http’)

and why I need it? What is the purpouse of 8124 and 127.0.0.1?

Node is built in modules and to use one of them you must first include it with require. Just like the example above with require(‘http’). In the same manner you can include every module of Node.

What are the Node’s modules are pretty well described in the API page. Well I’d like to say that the API page is quite insufficient. That is very bad, cause most of the code you’ll need developing a node.js applicatoin isn’t described/explained there. Continue reading Diving into Node.js – Very First App →