PHP and Zend
Friday, February 4, 2011I was asked to take a quick look at getting a PHP extension to work. Little did I know the can of worms that particular question would open.
Some of my coworkers were trying to evaluate a piece of PHP based support call and ticket tracking software called Kayako. This particular web application uses Zend Guard to protect its code. The application hasn't released a version using Zend Guard 5.5, which added support for PHP 5.3. This is quite important because I attempted to bring up a virtual machine to aid in my coworkers testing Kayako.
After getting the virtual machine setup with Ubuntu 10.04.1, using the OpenSSH Server and LAMP Server canned configuration options to get a good set of necessary, base packages for this particular use case, I did a safe-upgrade, rebooted (new kernel), and added the "zendframework" package. The next step was to add support for running Zend Guard encoded applications, which is provided by the Zend Guard Loader (formerly called the Zend Optimizer). This is done by way of a binary that is setup in the php.ini according to the included README:
[zend]
zend_extension=/opt/ZendGuardLoader-php-5.3-linux-glibc23-i386/php-5.3.x/ZendGuardLoader.so
zend_loader.enable=1
zend_loader.disable_licensing=0
A quick reload of Apache, and the "with Zend Guard Loader v3.3" appears in the phpinfo() page. However, since I used the current version of PHP, and the corresponding Zend Guard Loader -- I was doomed to fail. As Kayako was encoded with Zend Guard for PHP 5.2. Apparently, Zend Guard Loader for PHP 5.3 does not support loading files encoded for earlier versions. This, I discovered after searching for the error from my Apache error_log:
[Thu Feb 03 22:31:21 2011] [error] [client 192.168.10.26] PHP Fatal error: Incompatible file format: The encoded file has format major ID 3, whereas the Loader expects 4 in /var/www/kayako/setup/index.php on line 0
I guess that this shouldn't be so frustrating. But I do find it rather annoying that there is no backward compatibility. This is somewhat exacerbated by the fact that PHP 5.3 was first released in June 2009, nearly 2 years ago. Not only from the perspective of maintaining legacy versions (granted, 5.2 still seems to be actively maintained), but the amount of release lock-in that comes with not supporting loading older versions in newer releases means that customers of the Zend Guard encoder need to keep updating (or at least releasing up-to-date encoded versions of their supported releases. I think that the associated cost of protecting the PHP source with this mechanism is too high.
However, Zend to the rescue! I don't even need to pin the 5.2 series of PHP in my package managed Ubuntu environment. There is a Zend Server Community Edition which is a bundle that includes all of the necessary components to run a Zend Guard encoded application of either the previous (5.2) or current (5.3) version. This bundle is available for various platforms (including Linux and Windows) and certainly seems like the easiest way to get a Zend Guard application up and running without fighting version incompatibilities. But that isn't necessarily the easiest way to manage a particular web application, unless you subscribe to the single-service-per-machine philosophy.
So, while I find the whole situation very frustrating, specifically the whole no backward compatibility thing, I do think it's nice that the "community edition" bundle is available to get applications up and running.
Useful links from this endeavor: