Earlier this month Matt posted a provocative article on rich internet applications. Here’s a taster:

Ajax is a dangerous and immature technology. It is, in fact, a hack—a kludget—to provide rich-client functionality in the browser.

And here’s my equally blistering riposte.

Hear that sound? It’s the CEO of Oddpost, which was one of the first Ajax apps, and which sold for a reported US$30 million to Yahoo. He’s crying himself to sleep ’cause Matt said his technology sucked. My point is not (just) to lampoon Matt, but to point that Ajax does work, and is worth a lot of cabbages. Clearly a lot of people are using it so it can’t be that hard.

Matt says “Ajax (as currently exemplified by Javascript and XML over HTTP) is certainly only version 0.5”. Now I don’t think that is entirely fair. There a many toolkits and libraries that make developing Ajax applications easier and more robust. Debugging support isn’t so bad either. As for type checking…well I’m giving that one to Matt. At least for now.

So in conclusion I argue that’s Matt case is not proved. In your face Matt! Tune in next time when we kiss and make up. Or Matt gives me a black eye.

Ben Simon implements the Java Petstore in Scheme using the excellent SISCWeb framework, which runs in the equally excellentSISC Scheme implementation. Well worth a look, particularly thewriteup which explains some of the advantages Scheme brings to web development.

Firefox 1.5 beta 1 is out. I’ve been tracking Deer Park (the pre-beta releases of Firefox) for a while now so I’m excited to see this new release. I’m particularly enthusiastic about the canvas support as I’m having fun playing around with vector graphics. The Firefox canvas is much more complete, though slower, than Apple’s buggy implementation in Safari. The other new features don’t excite me as much, as the web applications I develop run on the general Internet. If you have a closed environment they will be more useful. In such an environment, XULRunner becomes very interesting.

I see via Ditchnet.org that IE 7 Beta 1 is out, and support for CSS 2.1 is in the works. For comparison, see what Deer Park Alpha 2 (the next version of Firefox) includes. It looks like IE 7 is going to be a good browser for 2004, and an ok browser for today. This is still good news for web developers, because IE 6 is a terrible browser for today.

If MonetDB is half as good as claimed it will be a big improvement over current databases. Certainly worth a look.

Also worth a look is Sedna, a XML database with a Scheme API.

Go to Yahoo and you’ll see a riot of news stories, links to services such as Yahoo Messenger, and right at the bottom of the page… a link to the service that launched the company, the Yahoo Directory. It is laughable now to think that a human maintained directory could keep pace with an powerful search engines and exponentially growing web, but for a long time Yahoo’s directory was the web’s best way to find information.

Early search engines considered only the text of a web page when searching. They could find all the pages that contained the words you were looking for, but they could not tell you which ones were important, leaving you to sift through the hundreds or thousands of results. In this situation going to Yahoo’s directory was a short-cut to finding the most important pages on any topic. It might take you six or seven clicks to drill down through the hierarchy but you’d get there in the end.

Then along came Google. Enter some keywords and Google will give you the all pages that match those keywords, ordered by importance. In most cases, Google is sufficient. The key innovation in Google is that recognises that people indicate the pages they consider important by linking to them. Google uses that information to rank pages via the PageRank algorithm. With millions of web pages individual variations don’t count for much, and what you end up with is the pages generally considered best.

There is a big idea behind the PageRank algorithm, which is that people implicitly tell you what is important to them. The Yahoo model was to explicitly ask people what is important to them. This doesn’t scale. Implicit measures scale better, and in fact perform better as size grows, as noise in the measurements cancels out.

Fast-forward to today. One of the hottest things on the web at the moment are services like del.icio.us that asks people to tag pages or assign ratings to them. This is another example of explicit feedback. You don’t have to look long at the most popular tags on del.icio.us to see that the demographics are skewed heavily towards the geek end. Now explicit feedback is great if you can get it, but while you can expect obsessive-compulsive geeks like myself to meticulously organise their links, but you can’t expect the man-on-the-street to do the same. What is needed is implicit feedback.

For services like del.icio.us that aggregating pages on a common theme, there are a number of algorithms that will apply PageRank in a topic-sensitive manner (for example, the aptly named topic-sensitive PageRank). For services that maintain rating of pages, there has been quite a lot of work on implicit ratings, collated in this excellent recent survey. Several studies show that reading time is correlated with interest. If you run a web site, this is one statistic you can easily gather, and one that the Attention.XML
spec includes. If you write web browsers there are bunch of other measurements you can gather, such as scrolling and bookmarking. Of course for most of us these measurements are out of reach!

Explicit measures have one advantage: they are much easier to get started with. If I rate a blog post as “good”, the meaning is unambiguous. If I spend 30 seconds reading it you need some sort of model to convert that into a rating, and to build that model you need a fair amount of data, knowledge of machine learning techniques (we can help), and probably some beefy hardware to handle large numbers of users. For small services this may be too much, but for large services it is the way forward.

In Safari 1.3 Apple introduced a new canvas tag along with Javascript extensions that enable 2D vector graphics to be drawn directly onto a web page. This extension has since been incorporated in aWhatWG specification and Mozilla have followed up with an implementation that’s available in the latest Firefox 1.1 preview release. We have two demos up here and here. This essentially enables a lot of the power of Flash from within a normal web page.

Apple’s motivation to was to enable Dashboard, but as we discussedearlier the potential for this technology extends much further. Existing web technologies such as CSS, the DOM, and Javascript allow highly interactive applications, as GMail and Google Maps have shown. However there are still some limitations: the developer cannot create custom widgets or draw complex graphics in the web-browser. The canvas solves this problem. Now that Firefox is implementing the canvas it makes it viable to release cross-platform graphic rich applications. This is a whole class of applications that so far the web hasn’t been able to touch. Think about Adobe Illustrator running within your web browser. This is one to watch!

Xyle looks like a nifty tool for working out how a CSS design was created. It only works on Safari, so for most people the Web Developer plugin for Firefox will be more useful. Xyle does have a few features that WD doesn’t, so if you have Safari and the $15 I’d say it’s worth it.