Andrew Martin has a new post to his blog looking at a technique that could be used to help minimize some of the performance issues you could see on AWS micro instances dealing with PHP session handling. His alternative is serving them from a RAM-based disk instead.

It's rare to find a web server with slow disk I/O performance, but Amazon's EC2 micro-instances are one such example. Their EBS disk subsystem access is rated "low", and this can have a detrimental effect on HTTP throughput. [...] This leaves sessions, which can be written to a redundant and fault tolerant storage system. [...] In order to speed up the disk access, a RAM-based disk can be mounted over the session directory. This has the disadvantage of being volatile - the data is lost in case of a server reboot, or the mount point being unmounted. However if tolerable, storing sessions in RAM insulates the application from poor filesystem performance.

He mentions the two types of kernels that can be used, ramfs and tmpfs, and the specifics of using a tmpfs filesystem to implement the technique (complete with command line calls to make it happen).

Juozas Kaziukenas has a new post to his blog today looking at using Phing to keep files in sync on a shared hosting, FTP only kind of environment.

Today I was trying to use [Phing] in shared hosting server, but as you will see, Phing can't do a lot of it's functionality without direct access to server (over shh for example). [...] Things get worse, when you try to sync files in shared hosting environment, where only FTP is available. [...] Code in the hole some months ago posted solution which uses Net_FTP (FTP functionality wrapper) package to upload files to server. I decided to try given solution, so I modified it to download source code from SVN first and then upload them.

His Phing configuration sets up the application, defining the source directory, the files to push, the FTP connection to make and pushes the files over out of an svn export. He has a slightly different solution (no code/config for this one) that would grab the last revision value from the remote server and only push out the files have have changed since then.

On the SitePoint PHP Blog today Troels Knak-Nielsen takes a deeper look at two of the superglobals a lot of PHP developers take for granted - $_GET and $_POST.

When a PHP script is invoked by a web server, it is as the result of a HTTP request. A HTTP request has a target URI and that URI consists of different parts. One of these parts is the query. As the PHP process starts up, the query gets parsed into an associative array. And for some reason, somebody decided on the unfortunate $_GET, because it's what you use for GET requests - right? Wrong!

He points out that all HTTP requests, regardless if they're GET or POST will have that GET information (not necessarily in $_GET, though). He also mentions another commonly used (and sometimes abused) superglobal - $_FILES. His biggest gripe, though, is that the naming of the variables confuses the developer as to the true content of the HTTP request.

And I won't even comment on the nastiness of $_REQUEST.

The PHPBuilder.com site has a quick new tutorial showing how to upload images to your server via a PHP script (including some error checking).

One of the most frequently asked questions about PHP is "how can I use PHP to upload an image". In this article we'll discuss the details of how you can do just that!

Their script is done in three steps - an HTML form to accept the input, the PHP script to handle the upload (working with the $_FILES superglobal) and another HTML page to let the user know their upload was a success. When the file is uploaded, they check for a few things: the internal error PHP could throw, ensuring that the uploaded file exists and checking to ensure that the file is an image. Only then is it moved over to the true uploads directory to be stored.

Tiffany Brown has a quick tutorial on a pagination method she's come up with for splitting out array contents over multiple pages.

While working on a recent project, I had to build a feature that displayed a list of files available in a directory. A simple way is just to use scandir() and a foreach loop to spit out a pretty list. There's a small problem though: long lists aren't all that user friendly. I decided instead to paginate the results. Here's one way to do it using PHP 5.

Her method reads in all of the (valid) files from the directory, assigns them to an array and uses the array_chunk function to split them up into groups on five. These groups can be easily looped through and displayed out as links easily.

On DevShed today there's a new tutorial showing how to build file upload functionality into your scripts.

If you're a PHP developer who has built a certain number of web applications, then it's quite probable that you've already worked with HTTP file uploads. [...] First I'm going to teach you how to handle file uploads using a procedural approach, and then, with the topic well underway, by way of the object-oriented paradigm.

The introduce the beginners out there to the $_FILES array (a superglobal) that contains the details about the file(s) that have been submitted. Next comes the construction of a simple form and how to handle the submission on the PHP side.

The Zend Developer Zone has posted security tip #15 today, focusing on an easily forgotten aspect of web development (not just in PHP) - forgetting to remove temporary files.

As developers, most of us are very messy. I've worked on countless projects and at each either run across or left a trail of diagnostic files laying around. (info.php, test.php, doMe.php, etc.) These tiles, if found by someone with nefarious intent, can leak valuable information about your system.

Always remember to remove these types of files...as Cal puts it:

It would be a shame to spend all that time securing your application only to leave info.php or worse yet, a "quick piece of code" in test.php that could potentially leak dangerous information about your system. Don't help the ad guys any more than you have to.

DevShed has a new tutorial posted today with a look at one of the more common tasks performed with PHP (second to generating web pages, of course) - working with files. It can be a little tricky for a budding PHP programmer, but they've got the info you need to get started.

Reading and writing to files can be useful if you do not require the storing of important data, such as a web counter. I must warn you though, that this method of storage should not be used to store passwords and other critical information, as it is not safe. Here we will discuss how to handle files and directories in PHP, specifically, how to create, read and write them.

They start off with a look at file permissions on both Unix and Windows systems ot give you an idea of what problems they could cause. Then, it's on to the actual files themselves - for this part, though, they only look at reading them in and working with their contents.

Mike Potter has posted an update to his blog about the unofficial Adobe PHP SDK he mentioned earlier with details about new information and corrections that have been added to the guide.

I've updated the (unofficial) Adobe PHP SDK to fix some problems after the initial release. Turns out a few files were missing from the .zip file, and some files were misnamed. I've fixed these problems and also added in a new, more simple sample to show how Flex can retrieve XML data from a PHP backend, without requiring the use of a MySQL database. Finally, I've also removed the .svn files from the .zip file, reducing its size to only 1.5 MB.

You can download this latest version of the guide directly from his blog as well as get involved via the Google Group or requesting access to the SVN repository on Google as well.

If you're caught using PHP4 on Windows and have been seeing some issues with the older MySQL libraries you've been using lately, it might be time to upgrade. "But I can't move away from PHP4," you say. No worries - this new post from Edin Kadribaaic should have the answer you're looking for.

Since the main PHP 4 distribution cannot be updated with the latest MySQL libs for various reasons, I will provide downloads of the latest PHP 4 with the latest MySQL libs.

His archive contains two files, both DLLs to replace the MySQL libraries that already exist.