Tag Archives | CDN

Blog optimization update: WordPress, CDN, Speed, Caching, Accessibility

Keep Calm and Clear Cache

Keep Calm

I’ve continued to do some research on optimizing the blog responsiveness, and I’m pleased with the results. Anecdotal tests this morning, with no local caching, showed a 2 second load time with a 1.2 second DOMLoaded event. That’s pretty good. Here are a few notes on things I’ve been working on:

  • Google’s PageSpeed Tools offered some helpful insights.
  • Minifying some of the text assets – HTML, CSS, and JavaScript – is working well, though I’d like to be more easily able to toggle this for debuggng.
  • Using the Rackspace CloudFiles caching with WordPress lacks a good automated tool on the WordPress side to keep the cache synced with changes. I’ve been using the SuperCache plugin for local speedups, and it supports a variety of CDNs. The CDN-Sync-Tool plugin is no longer available on the WordPress.org site, and several forks on GitHub all seem to be out of date. It’s unclear, so far, where the problem is. The WP cron jobs are failing. Whether that’s an internal configuration problem, or unsupported calls to an old API, I haven’t worked out yet. Next time I try this, I’ll look at some deeper pilot testing for CDNs with better WordPress support.
  • Inspired by “Why Bother with Accessibilty” by Laura Kalbag, part of the excellent 24ways series, I did some initial accessibility testing. The WAVE Web Accessibility Evaluation Tool tests your site for accessibility, an essential feature these days. Accessibility makes your site more understandable and easier to navigate for all users. Disabilities aren’t someone else’s problems; they are a state we will all pass through at one stage or another.There are a few glitches in my templates that I will work to rectify. A larger problem s the observation that my style choices have lead to a rather low-contrast site.

New post testing CDN support on WordPress

DSCN1940 So, the Content Distribution Network is in place and several tests indicate it is working well — page loads are much faster, the URLs of the CDN content are re-written properly — but the next question is whether new materials will be automatically added to the CDN. The picture at the left (and yes, this is an excuse to post a cute dog picture, too) should appear with a link to the high-resolution (1.8 Mb) image. On the blog itself, that link should be of the format http://blog.tedroche.com/wp-content/uploads/2003/12/NameOfPicture.jpg, while if the picture is picked up by the CDN synchronization software, it should upload to the CDN and the URL be rewritten to http://static.blog.tedroche.com/etcetera. Let’s try it out and see what happens…

Woah. Success first time. Pretty cool.

Some details on what I’ve got set up: I’m using the Rackspace Cloud Files service as the CDN. I had worked with Rackspace before on some hosting projects, and have a friend working there, so I thought I’d try them out first. It appears that their CDN services are in an early stage and don’t have all of the features of soe of the more mature products. In particular, it appears that the blog software is reponsible for pushing any new or updated content to the CDN. By contrast, the Amazon S3 offering has an ‘origin pull’ feature that will pull content from the original source when it is first requested, and subsequently cache it.

In order to get the contents of my local blog to sync with the CDN, I added the CDN-Sync-Tool plugin. A lot of web searching seemed to indicate I could find this in the WordPress Plugins directory online, but the tool has been pulled from the directory. Apparently, it is undergoing some redevelopment. The version I found was on GitHub under https://github.com/WDGDC/CDN-Sync-Tool and installation was not more complex that downloading the ZIP and unzipping it in the plugins folder. Bear in mind that you should be comfortable with using the command line and have the skills to review the files you are installing on your machine, as there has been no review by the WordPress folks, and the code is currently under development and you may need to deal with bugs, incompatibilities and support problems. So, this isn’t the path I’d recommend for less-technical WordPress developers, and likely isn’t the path I’d recommend for a client looking to put a CDN into production use.

Note that most cache programs and their CDN features are set up in such a way that logged-in users may see a slower site, but more up-to-date, site, and that in order to test caching you’ll need to log out of your WordPress session.

 

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This work by Ted Roche is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States.