EllisLab has yet to update their website with the new User Guide but you are free to download 2.1.0 to see the changes.

Scanning through the change log, I see a lot that I like:

• Added increment_string() to String Helper
• Added is_unique to the Form Validation library.
• Added $config['use_page_numbers'] to the Pagination library, which enables real page numbers in the URI.

These were functions that I had to build on my own for practically every project so it’s nice to see them natively in CI now.

So what are you waiting for, Download CodeIgniter 2.1.0!

For the redesign of Women & Teens Healthcare, we decided it was time to use media queries to deliver the same content to mobile, tablet and desktop users. Not only does this make the site easier to maintain but it also provides an optimal experience for the user, regardless of their screen size.

The site is still under development but you can see some of the work below.

$ svn --version

You should see the following:

svn, version 1.6.16 (r1073529)
compiled Jun 13 2011, 15:54:33

Copyright (C) 2000-2009 CollabNet.
Subversion is open source software, see http://subversion.apache.org/
This product includes software developed by CollabNet (http://www.Collab.Net/)

To get started, we need to make a folder to store your repositories. The location is up to you but I’ll be putting it in /Library/Subversion/Repository.

$ mkdir -p /Library/Subversion/Repository
$ svnadmin create /Library/Subversion/Repository/myproject
$ cd /Library/Subversion/Repository/myproject/conf/

Edit svnserve.conf with your editor of chose

anon-access = none
auth-access = write
password-db = passwd
authz-db = authz

This will give no access to anonymous users and read/write abilities to users you specify
Now edit passwd to create your first user and assign them a password

[users]
your_name = SecR3t_p4ssw0rd

Edit auth to assign that user to a group and give that group permissions. This is handy if you want to give certain groups read only abilities.

[groups]
developers = your_name

[/]
@developers = rw
* =

Congratulations, you have now configured your repository!
To start running subversion, you need to use the command

$ svnserve --daemon --root /Library/Subversion/Repository

Even better, if you want to run this command automatically when your computer boots, make this a cron job.

$ crontab -e

Add

@reboot svnserve --daemon --root /Library/Subversion/Repository

After saving and quitting, check to see if the cron is running with

$ crontab -l

Now when your computer reboots, svn will start running automatically.

If you have any questions, leave them in the comments!

Goal: Stress our server as little as possible.

There are several ways of doing this but the basic process of how this works is:

1. Our users embeds an image on their site (e.g. <img src=”http://examples.com/images/ratings/1234/small/” />)
2. Someone view their webpage which makes a request to that URI
3. Our server has to look up the user (1234) to see if they exists
4. Get the current rating of that users
5. Figure out which image to display. (5 ratings + no rating) * 2 sizes = 12 possible images
6. Return the correct image

Pretty straightforward, but what if a user has a popular website or if this feature sees a lot of use. Our server will be doing quite a few database calls.

Current solution:

// Load the PNG
$im = imagecreatefrompng($_SERVER['DOCUMENT_ROOT']."/assets/images/$rating-$type.png");

// Settings for caching
$expires = 604800; // 1 week (60*60*24*7)
$lastModified = gmdate("D, d M Y H:i:s") . " GMT";
$eTag = "ci-".dechex(crc32($im.$lastModified));

// Make sure clients cache this image
header("Pragma: public");
header("Cache-Control: maxage=".$expires);
header("Expires: " . gmdate("D, d M Y H:i:s", time()+$expires) . " GMT");
header("Last-Modified: " . $lastModified);
header('ETag: "'.$eTag.'"');

// Outputs the PNG
header('Content-Type: image/png');
imagepng($im);

// Free up the memory used by the image
imagedestroy($im);

This makes dynamic chosen images cacheable so they only have to request once a week (by a single user) as opposed to every time they visit a new page.

I said current solution because I will most likely do server-side caching in addition to client-side.

Tip of the hat to Matt Midboe of RD2 for how to do the eTag part.

After tracking the server for a few days I notice it was constantly running low on memory. A quick investigation found that Apache2 was eating all of my memory which was negatively effecting my HTTP response times.

Apache Response Times

See if you can spot when the change took place in the graph below.

Server's RAM usage

I tweaked the settings in my apache2.conf which reduced the RAM usage (mpm_prefork_module):

    StartServers          2
    MinSpareServers       4
    MaxSpareServers       9
    MaxClients            20
    MaxRequestsPerChild   0

I’m sure these setting will change over time as the load changes and when I upgrade to more RAM.