Paul Turner » Apache

Internet Explorer 6 and HTTP compression

Paul — Fri, 22 Aug 2008 16:19:09 +0000

Recently I wrote about installing mod_gzip on CentOS 5. However since then I have discovered that Internet Explorer 6 has does not support this properly, and intermittently does not load items properly!

To resolve this I had to change the Apache configuration. This is the configuration that I am now using:

AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css text/javascript application/x-javascript
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4\.[0678] no-gzip
BrowserMatch \bMSIE\s7 !no-gzip !gzip-only-text/html
BrowserMatch \bOpera !no-gzip
Header append Vary User-Agent

This turns off the HTTP compression based on their user agent.

Here are some of the known issues:
http://support.microsoft.com/kb/321722/EN-US/ (IE5.5, IE6 and IE6SP1 always cache gzip encoded content)
http://support.microsoft.com/default.aspx?scid=kb;LN;Q312496 (IE6 http://support.microsoft.com/default.aspx?scid=kb;en-us;823386&Product=ie600 (IE6sp1, compressed HTML pages only partially appear)

And this is one of the sites I found to help with the resolution:
http://www.contentwithstyle.co.uk/Blog/147/

Installing PHP XCache on CentOS 5

Paul — Mon, 11 Aug 2008 09:35:19 +0000

XCache is a PHP opcode cacher, which basically means that it will cache the compiled code the first time a PHP page/script is executed thus avoiding the compilation step on subsequent executions.

I used the 1.2.2. release of XCache and followed the quick guide instructions to install from source.

The installation requires that the php-devel package is installed. This is required to compile PHP extensions (the comand phpize is required for this installation).

[root@testserver xcache-1.2.2]# yum install php-devel
Dependencies Resolved
=============================================================================
Package Arch Version Repository Size
=============================================================================
Installing:
php-devel i386 5.1.6-20.el5_2.1 updates 512 k
Updating for dependencies:
php i386 5.1.6-20.el5_2.1 updates 1.1 M
php-cli i386 5.1.6-20.el5_2.1 updates 2.1 M
php-common i386 5.1.6-20.el5_2.1 updates 154 k
php-gd i386 5.1.6-20.el5_2.1 updates 113 k
php-ldap i386 5.1.6-20.el5_2.1 updates 35 k
php-mbstring i386 5.1.6-20.el5_2.1 updates 969 k
php-mysql i386 5.1.6-20.el5_2.1 updates 84 k
php-pdo i386 5.1.6-20.el5_2.1 updates 62 k
php-xml i386 5.1.6-20.el5_2.1 updates 94 k
Transaction Summary
=============================================================================
Install 1 Package(s)
Update 9 Package(s)
Remove 0 Package(s)
Total download size: 5.2 M
Is this ok [y/N]:

It appears that this will also update the core PHP package and dependancies, so care should be taken. Try this on a test server and not your production server!

Here are the steps I took to install XCache:

[root@testserver ~]# tar -zxf xcache-1.2.2.tar.gz
[root@testserver ~]# cd xcache-1.2.2
[root@testserver xcache-1.2.2]# phpize
[root@testserver xcache-1.2.2]# ./configure --enable-xcache
[root@testserver xcache-1.2.2]# make
[root@testserver xcache-1.2.2]# make install
[root@testserver xcache-1.2.2]# cp /etc/php.ini /etc/php.ini.bk
[root@testserver xcache-1.2.2]# cat xcache.ini >> /etc/php.ini

In my configuration the xcache.ini and resulting php.ini had the wrong path to the module that has been installed. The module was installed in /usr/lib/php/modules/ but the configuration was looking in /usr/local/lib/php/extensions/non-debug-non-zts-xxx/.

All that was needed was a simple change to the configuration file to comment out the fully qualified path and tell it to use the extensions directory:

[xcache-common]
;; install as zend extension (recommended), normally "$extension_dir/xcache.so"
;; zend_extension = /usr/local/lib/php/extensions/non-debug-non-zts-xxx/xcache.so
; zend_extension_ts = /usr/local/lib/php/extensions/non-debug-zts-xxx/xcache.so
;; For windows users, replace xcache.so with php_xcache.dll
;; zend_extension_ts = c:/php/extensions/php_xcache.dll
;; or install as extension, make sure your extension_dir setting is correct
extension = xcache.so
;; or win32:
; extension = php_xcache.dll

Then just check it’s installed:

[root@testserver xcache-1.2.2]# php -v
PHP 5.1.6 (cli) (built: Jul 16 2008 19:53:00)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies
with XCache v1.2.2, Copyright (c) 2005-2007, by mOo

Success! However Apache must be restarted in order for this to work with PHP web pages.

service httpd restart

Now if you access a page containing the phpinfo(); function you should be able to search for XCache and find it.

XCache is now installed and running.

I did not see the need to install the php-devel package on our live servers and I know that our live servers are identical to our test servers other than hard disk and memory sizes (we use VMWare extensively and they come from the same template).

This means that all the binaries compiled on the test server should be compatible with our live servers, so I just copied the xcache-1.2.2 folder from the test server and followed the above steps again starting with the “make install” step.

[root@testserver ~]# tar -cvzf xcache-install.tgz xcache-1.2.2/

copy this to the /root/ directory on the live server

[root@liveserver ~]# tar -xvzf xcache-install.tgz
[root@liveserver xcache-1.2.2]# make install
[root@liveserver xcache-1.2.2]# cp /etc/php.ini /etc/php.ini.bk
[root@liveserver xcache-1.2.2]# cat xcache.ini >> /etc/php.ini
[root@liveserver xcache-1.2.2]# vi /etc/php.ini
[root@liveserver xcache-1.2.2]# php -v
PHP 5.1.6 (cli) (built: Sep 20 2007 10:16:10)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies
with XCache v1.2.2, Copyright (c) 2005-2007, by mOo

Installing mod_gzip on CentOS 5

Paul — Fri, 01 Aug 2008 12:50:50 +0000

CentOS 5 is packaged with Apache 2 which is not compatible with mod_gzip. The module mod_deflate is the Apache 2 equivalent.

Installing mod_deflate on CentOS 5 is a fairly simple process. The module is included in CentOS 5 and just need to be configured.

The only changes required are to the Apache configuration file /etc/httpd/conf/httpd.conf. I recommend that you take a backup before you make any changes.

Here are the steps that I took:

1. Check that the deflate module is loaded.
In my configuration file this was already done with this line:

LoadModule deflate_module modules/mod_deflate.so

If this is not there then I suspect all that is required is to add this line. However if you need to do this I recommend that you check the module /etc/httpd/modules/mod_deflate.so is installed.

2. Configure the deflate module
All that was required was to add the following lines to the Apache configuration file.

Update 26/08/2008: Originally I only had the first line of the above configuration. However it turns out that there are issues with Internet Explorer 6 and HTTP compression.

I added this after

AddType text/html .shtml
AddOutputFilter INCLUDES .shtml

but you should be able to add it anywhere in the main section.

3. Restart Apache

service httpd restart

4. Test it’s working
The easiest way to check that it is working is with the YSlow plugin for Firebug. Firebug is a Firefox plugin that will give you lots of useful information.

To test just load a page in your browser, go to the Firebug/YSlow plug and select the “Performance” option. This will give you a performance grade. You should hopefully see an “A” for “4. Gzip components”. If not do a Ctrl-F5 to ensure that you’re not viewing cached content.

If this still does not report an “A” for “4. Gzip components”. then it is possible that your page has other content types that need to be added for YSlow to be happy.

Summary
This is only a quick overview of the steps I took, and by no means comprehensive A more detailed tutorial is available here: http://www.howtoforge.com/apache2_mod_deflate