The goal of web performance optimization is to become faster and smaller: research at Yahoo! and Google found that just 10-20% of the perceived loading time is caused by the server. A few years ago we thought performance was exclusively connected to the server. However, 80-90% of the loading time incurs in the frontend. Thus WPO is more efficient targeting the frontend.

Two important weak points are JavaScript files and the sheer number of files: JavaScript loads sequentially and blocks subsequent code until each file is loaded. Hence it shouldn’t be located in the head, but in the foot of a page. Secondly older browsers, in particular Internet Explorer, will only load 2-4 files in parallel. Files queue up and get processed when it’s their turn. Therefore aggregation of files is used for reducing the number of HTTP requests.

Several international companies have conducted research or just tracked the effects of optimization.

Effects of slowness

• Amazon: 100 ms delay caused a 1% drop in revenue.
• Google: 400 ms delay caused a 0.59% decrease in search requests per user (earlier tests list larger numbers).
• Yahoo!: 400 ms delay caused a 5-9% decrease in traffic.
• Bing: 2 seconds delay caused a 4.3% drop in revenue per user.

Effects of speed

• Mozilla made their download page 2.2 seconds faster and was rewarded with an increase of 15.4% in downloads.
• Google Maps reduced the file volume by 30% and observed a 30% increase in map requests.
• Netflix enabled gzip on the server; simply by this single action pages became 13-25% faster and saved 50% of traffic volume!
• Shopzilla succeeded in reducing the loading time from 7 down to 2 seconds, whereby the conversion rate increased by 7-12%, they observed a 25% increase in page requests, they were able to retire 50% of their servers, thus saving energy costs.
• AOL observed the number of page views on several websites. While the fastest users requested 7-8 pages, the slowest only viewed 3-4.

As a cream topping Google recently announced to factor in the site speed as a parameter in web search ranking.

Eventually pages become faster, clients are happy, generate more revenue and page views, while power consumption and CO₂ emissions decrease. Saved the world, again! And if you’d like to contribute, start by checking the rules at Yahoo! A few tricks beyond that can be found in the presentation which will be translated soon.

The main idea is to present leading innovators and their perspectives on eAccessibility from the technical, political, and economic side. Experts on seven panels will briefly describe their own work and their view of accessibility and then discuss the issues.

There’s an illustrious line-up of speakers including Deutsche Bahn, the European Commission, France Télécom, the German Federal Ministry of Labour and Social Affairs, Google, IBM, Microsoft, Mozilla, Opera, the W3C, the Web Standards Project, and Yahoo! talking about these topics:

• Accessible Web Applications
• Mobile Access — Device-independent or Accessible?
• Comparison of National Accessibility Guidelines
• Accessible Rich Internet Applications (ARIA)
• Web Standards and Accessibility in Higher Education
• Harmonising European Accessibility Guidelines
• The Business Value of Accessibility

If you have been following my posts in the last two years this will sound slightly familiar. Furthermore I’m honored to have Linda Mauperon, Member of Cabinet of the European Commissioner for Information Society and Media (Viviane Reding) as our keynote speaker. Please see the detailed description of the panels in the conference program.

We would like to take a look on accessibility from different perspectives presenting pioneering thinkers whose organizations have established accessibility in their business and communication long since — and making serious money with it. There should be something of interest for everybody among the topics: for techies, consultants, employees from universities and companies. The conference is limited to a maximum of 200 attendees. Registration opens next week.

Of course there are various gems under the hood of the website, too. Naturally it is extensively accessible (check the cool skip links), but it is also incredibly fast because Yahoo!’s best practices for frontend performance are regarded. There are separate style sheets for printing, for iPhones, and for handhelds. The CMS is WordPress µ, having the advantage of administrating both the English and the German version with the same installation.

Other conferences

The next geek meeting held in Frankfurt will be the Webmontag (Web Monday) on September 1st where I will give my presentation about canvas a short test drive.

A few days later on September 4 I have the honor of the opening talk at the Web Congress at the University of Erlangen, again about canvas, only this time a full hour.

On September 25 there’s the Best of Accessibility Symposium in Düsseldorf where I hold a workshop about hands-on ARIA (you recognize the pattern?).

On October 10-11 an internal namics conference called T-Camp is held in Basel, with my colleague Alex Stirn and me speaking about Professional Frontend Engineering.

A conference I’m looking forward to because of the many experts attending and the fair prices is the A-Tag (Accessibility Day) in Vienna, Austria, on November 21. Again I will sing praises of ARIA. This innovative technique can’t be evangelized enough! There’s no website yet for the A-Tag, but I’d recommend to book your journey well in advance to catch the inexpensive flights to Vienna. The conference itself cost only € 35 last year is free because it is sponsored by the Austrian government.

If you happen to be around, don’t hesitate to speak to me.

What are the alternatives? Using background-images with off-screen text? Bad code:

1. <a href="foo" class="button">
2. <span>Alternative Text</span>
3. </a>

1. a.button, button {
2. background: url(foo.gif) 0 −26px no-repeat;
3. display: block;
4. height: 52px;
5. overflow: hidden;
6. position: relative;
7. width: 150px;
8. }
9. span {
10. left: −9999px;
11. position: absolute;
12. top: auto;
13. }

That’s a bad idea with accessibility issues. Screen readers will be able to read the text, but if somebody with low vision has high-contrast custom stylesheets, it is likely that the background-image won’t be displayed. Still the alternative text will be invisible off-screen, so the link or button becomes unusable.

A better solution

Now Google’s accessibility specialist T.V. Raman explained their idea for replacing images with sprites. Here are screenshots of Google search results with images, and with background images disabled:

Google puts the alternative text behind the background image simply by attaching it on the span element, not the anchor. So when CSS or background images are turned off, the text just reappears.

1. <a id="logo" title="Go to Google Home" href="http://www.google.com/">
2. Google
3. <span></span>
4. </a>

1. #logo {
2. display: block;
3. height: 52px;
4. overflow: hidden;
5. position: relative;
6. width: 150px;
7. }
8. #logo span {
9. background: url(foo.gif) 0 −26px no-repeat;
10. height: 100%;
11. left: 0;
12. position: absolute;
13. top: 0;
14. width: 100%;
15. }

There’s only an issue if you have a lot of alternative text, perhaps combined with text zoom, so that it doesn’t fit in the reserved space. But I can live with that.

Congratulations to Google for this ellegant solution, and it’s so simple! Why didn’t I think of it?

So when Chris mentions JavaScript badges for del.icio.us, I think of Ed Eliot’s PhpDelicious or how to get similar results in WordPress. Naturally when he had the splendid idea to add captioning to YouTube videos with Google’s JavaScript API, I asked myself if there wasn’t a better way. There is, but to my surprise neither YouTube nor Yahoo! Video take advantage of that capability:

1. It’s common practice to implement text content in Flash via XML.
2. DFXP is a W3C XML standard for captioning videos.
3. There are free tools like MAGpie for creating captions, and they all support DFXP.
4. If YouTube or Yahoo! Video would allow users to upload and attach a DFXP file to a video, it would become dead easy for anybody to caption it. Not only for the filmmaker, captioning could be crowdsourced!

Just anticipating Joe Clark’s inevitable (and justifiable) objection: of course captioning is not an easy thing that anybody can do, to do it right it requires people with special training. But considering the number of videos on those platforms the only affordable and practical solution to provide any captioning at all is crowdsourcing. That can also be applied to the control of quality, accuracy, or reporting abuse.

Of course this would enhance primarily accessibility, but the XML files would further help search engines to index video content. And their marketing people would love such a feature for the positive PR!

Well, I submitted the suggestion both to Google and Yahoo!, you can vote on the Yahoo! Developer Network for it (Google is more closed-lipped). I’m curious who will be the first to offer that feature …

A little known W3C standard is the Platform of Internet Content Selection (PICS). You can tell from the poor layout that it’s a very old standard — in fact all of its parts are from 1996 and 1997. OMG, that’s ancient! That’s even older than HTML 4, CSS, or the Web Content Accessibility Guidelines!

PICS is a system for self-labeling. That raised some concerns about censorship in 1998, but governments who really want to censor their population’s internet access have found more effective ways to block content (I, for one, can recommend Tor as a countermeasure, also available as a Firefox extension, though I cannot guarantee your government approves it). So what remains is a meta element with information about your website, accompanied by a machine readable RDF/XML file.

1. <link rel="meta" href="/pics-label.rdf" type="application/rdf+xml" title="ICRA PICS label" />
2. <meta http-equiv="pics-label" content='(pics-1.1 "http://www.icra.org/pics/vocabularyv03/" l gen true for "http://learningtheworld.eu" r (n 0 s 0 v 0 l 1 oa 0 ob 0 oc 0 od 0 oe 0 of 0 og 0 oh 0 c 1))' />

Since in the nineties internet progress was driven by porn, PICS is mostly about child protection, although it can be used to describe a machine readable privacy statement and other things as well. Think of an early predecessor of the Semantic Web. Or in microformats it would be hPorn. Well, I assume very few of you run xxx sites, so why am I wasting your time with this post?

Because the PICS standard is most convenient when your website is not pornographic. The standard provides a way to label your website and distinguish between pictures of naked people as Greek ancient sculptures, in an educational or journalistic context, or as mere porn. But despite the name it’s not only suitable for rating pictures, it’s for text content or user-generated content as well, among other criteria. Plus the PICS label is recognized by Google, so it’s not about rushing ahead and self-censoring to please our overlords, it’s a measure to maximize the target audience and avoid mislead traffic. I believe a few of your clients may appreciate that. For example although this post uses quite a few trigger words, PICS provides a way to tell search engines and cybersitting software about the true nature of this article. I love that ability!