Zero to One-Eighty » plugins

Bad cookies

Adrian Cooke — Sun, 23 Aug 2009 17:51:47 +0000

Flash… ah-ahhh…

More than half of the internet’s top websites use a little known capability of Adobe’s Flash plug-in to track users and store information about them, but only four of them mention the so-called Flash Cookies in their privacy policies, UC Berkeley researchers reported Monday.

Unlike traditional browser cookies, Flash cookies are relatively unknown to web users, and they are not controlled through the cookie privacy controls in a browser. That means even if a user thinks they have cleared their computer of tracking objects, they most likely have not.

Ah, but there’s more:

Several services even use the surreptitious data storage to reinstate traditional cookies that a user deleted, which is called “re-spawning” in homage to video games where zombies come back to life even after being “killed,” the report found. So even if a user gets rid of a website’s tracking cookie, that cookie’s unique ID will be assigned back to a new cookie again using the Flash data as the “backup.”

You had better read the whole thing.

Cleaning up

More light reading about this glorious privacy debacle:

Adjust your Flash Global Privacy Settings
Adjust your Flash Website Privacy Settings
Overview piece: “How Flash Cookies Threaten Your Privacy”
Wikipedia page on Local Shared Objects
Mozilla Firefox plugin: BetterPrivacy
Windows optimization, privacy and cleaning tool: CCleaner
Flash cookie removal tool for Mac OS X: Flush.app

Warning on the first two links: you might find, as I did, that going to a weird-arse Adobe web page over plain old http with no authentication to adjust your Flash privacy settings is creepy. Thank you, once again, Macrodobia for making Internet so fun.

Identify yourself

Adrian Cooke — Mon, 20 Apr 2009 00:03:29 +0000

Identify is a Firefox extension by Glenn Jones that uses the Google Social Graph API to identify people based on the rel="me" link attribute. It’s easy to use—“Ctrl + I” (Mac) or “Alt + I” (Windows) on someone’s Twitter profile, for example—it pulls in available data from the present site and other social web sites. According to Google’s API, the plugin can identify public URLs that belong to the person being looked up, and publicly declared connections between that person and others. The plugin gives a sense of how quickly one can be identified when software aggregates information spread across multiple applications. So, you know, be careful.

Via Marshall Kirkpatrick.

Faster

Adrian Cooke — Sun, 22 Mar 2009 09:42:52 +0000

I ran around in the yard with my dog today, partly to remind myself how perfectly in shape I’m not, but mainly because she thought it was the best fun ever, and she draws a lot of water around here. Then the temperature dropped, I came inside, and parked in front of my computer. Father of the year? You bet.

This post is actually about things I’ve done (that have worked) to speed up WordPress 2.7 on shared hosting:

Output compression: compresses the text transferred (HTML, stylesheets, scripts, etc.) for browsers that indicate they can handle it. For example:


AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/x-httpd-php
AddOutputFilterByType DEFLATE application/x-httpd-fastphp

Expires headers: sends the browser an expiration date for some assets like stylesheets and images so it won’t try to fetch them again until that date is reached. Stylesheets have timestamps appended (e.g. style.css?1237154177) when they change, effectively changing the filename and forcing them to be updated. For example:
```
ExpiresActive On
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType text/css "access plus 10 years"
```
WP Cache 2: a plugin that reduces the amount of server-side code execution and database queries required to serve a page, by caching them as static files
Simple markup: lean, semantic markup using the HTML5 doctype and as little extraneous cruft as possible
Simple styles and behaviours: using only one external CSS and one external JavaScript file, both modest in size

Yahoo!’s YSlow plugin for Firefox and the associated rules helped a lot with the first two things, and Andrew King’s website optimization analyser with general performance testing. More recently I discovered Alex Shiels’ Is My Blog Working—it’s a nice tool though it seems to draw different conclusions as my server’s response time fluctuates.

So that’s that. Citius, altius, fortius, because, as everyone knows: Internet is serious business.

Thirty-one

Adrian Cooke — Sun, 08 Feb 2009 12:00:41 +0000

That’s the number of stylesheets you can include in a HTML document in Internet Explorer before it starts to ignore you:^†

You can create up to 31 styleSheet objects with the createStyleSheet method. After that, the method returns an “Invalid Argument” exception.

This can create a problem for module-based content management systems like Drupal where you can have multiple stylesheets for one module, and multiple modules. (It’s an application design approach that really puts the “cascade” in Cascading Style Sheets.)

Fortunately, Drupal allows you to aggregate and compress CSS files in the Admin settings (part of Drupal Core since version 5, I think). Unfortunately, in IE there’s a CSS file size limit (288 KB), at least in versions 6 and 7, so aggregation won’t solve the problem in every case.

To put this in perspective though, 31 is a lot of HTTP requests, and 288 KB is one hell of a CSS file. Numbers like these will likely have a negative impact on the user experience by slowing your site down. The YSlow Firefox plugin (requires Firebug) is good at identifying such problems.

As for the file size problem, James Edwards’ Dust Me Selectors can find unused CSS selectors for the entire site, which should allow some trimming. And of course there’s GZIP compression. Yahoo! Developer Network has an excellent best practices page that covers these topics. Best of all, Wim Leers has applied the Yahoo! rules approach in his detailed article about speeding up Drupal 5 and 6.

† Observed in IE6, IE7 and IE8 RC1.

Spam Karma released under GPL

Adrian Cooke — Thu, 17 Jul 2008 02:59:26 +0000

Dr. Dave discontinues development of his anti-spam WordPress plugin and licenses the source under the GPL. I’ve been using Spam Karma, and Michael Hampton’s Bad Behavior, on this site for around two years to great effect. Dr. Dave is stepping down and making the project available for others to take over. He cites time as one major reason, and the state of WordPress development as the other. Fair enough. Best of luck on future projects, Dave.

Navigation via the link element

Adrian Cooke — Tue, 01 Jul 2008 03:58:00 +0000

Pretty much every navigation menu on every site is different. They have commonalities, but obviously they’re not exactly the same. The minute you want to find something else on the site you’re viewing a small part of your brain energy goes into figuring out what’s available to get you there. You probably look for a navigation menu, some persistent pattern of options that outlines the site’s scope and allows you to move across, down into, or up and out. Unless the designer hates you, you’ll probably find the navigation in the same place on each page. It will take you time and effort to move your mouse there. Not much, but some.

Opera’s Navigation Bar.

Another way to provide navigation is through the page’s meta information. If you mark up the head of each page with link element relationships to nearby documents then visitors with a capable user agent can navigate to nearby stuff using their application controls. Opera is one such browser. Note the available Home, Previous, Next and Author buttons on the lower toolbar in the screenshot. There’s also a Firefox plugin called Link Widgets that works in a similar way. The blue arrow buttons are Top, Up, Previous and Next though there are others you can add by customising your toolbar.

Link Widgets for Firefox 1.5⁺.

In this scenario you expend some brain energy seeing which options are available, and some time moving your mouse to the one you want, say the “Previous” button. But the next time you come to a site that supports this type of navigation, you know those buttons are in exactly the same place, the same distance from each other, the same distance from your Reload and Back buttons, i.e. not far.

In HTML4 this was the intention of the link element: to provide a way for the browser to render links through the user interface (though I just learned about it). Opera’s implementation is quite addictive—fast the way a feed reader is when you’re skipping through a list of posts. I’ve no idea how widely supported this is, but it’s another tick for Opera. I think they are slowly winning me over.