I've been working with Jason Levitt (from Yahoo) recently to iron the wrinkles out of my Flash-based technique for making cross-domain requests. The main focus was to extend the reach of the technique to a larger audience, by adding support for Flash 7, which is more widely deployed than Flash 8.

Try the new FlashXMLHttpRequest demo.

Brad Neuberg's awesome work on DojoExternalInterface gave us a major boost. It emulates the most recent javascript to flash communication API (ExternalInterface, in Flash 8) accross platforms including Flash 7. The library hides differences with browsers and flash versions as much as possible, and works around various performance limitations.

Thanks again to Jason for his interest, feedback and support. I'm pretty excited to see what cool stuff he'll cook using this and the new web APIs from Yahoo.


If you only want to deploy this component, you can download the 'binary' package.
To modify the flash source files and re-build them, get the 'source' package.

As you can see in the demo/index.html file, after including dojo.js and FlashXMLHttpRequest.js, you'll need to initialize dojo and the flash object by calling InitFlash with the name of a function. That function will be invoked once the flash object is loaded and ready to make requests.
From there on, you can create FlashXMLHttpRequest instances and use the 'open', 'onload' and 'send' methods almost as you would with a regular XMLHttpRequest object. You can also call 'setRequestHeader', but only to set the content type request header.

More generally, FlashXMLHttpRequest still has some limitations, due to the native Flash capabilities.
First, access to other domains is restricted by use of a crossdomain.xml file.
Second, you can only make GET and POST requests. It will become possible to support other verbs, such as PUT, DELETE or HEAD, with the new APIs provided by Flash 8.5.

Let me know if FlashXMLHttpRequest is useful to you and if you encounter any bugs. Here's a more convenient permalink to this post: http://blog.monstuff.com/FlashXMLHttpRequest.

Overview

Web development incorporates all areas of creating a Web site for the World Wide Web. This includes Web design (graphic design, XHTML, CSS, usability and semantics), programming, content management, marketing, testing and deployment. The term can also specifically be used to refer to the "back end", that is, programming and server administration.

ref: Wikipedia: Web Development

The first 10 Prolog Programming Contests took place in Ithaca (1994), Portland (1995), Bonn (1996), Leuven (1997), Manchester (1998), Las Cruces (1999), Paphos (2001), Copenhagen (2002), Mumbay (2003) and Saint-Malo (2004). The contest organisers have written this book, containing the (slightly reworked) questions and an answer (in Prolog of course) for each question... The book is now also freely downloadable on this page.

For your enjoyment...

O'Reilly has published Computer Science & Perl Programming - Best of The Perl Journal. This is a compilation of articles originally published in The Perl Journal. Chapter 57, 'Spidering an FTP Site', is an article I wrote for The Perl Journal which describes how to recursively upload/download files and directories to/from an FTP site.

... the Flash ad contains code to open a popup that leads to a very different destination -- it's what I assume is an affiliate link that attempts to download and install ErrorSafe on your computer (link is to Symantec's description of it).

This, of course, would be totally against any ad company's guidelines. Masquerading as a banner ad, but discreetly opening a popup -- and not only that, but to what people consider malware -- is totally against any ad company's guidelines. So how did it get through?

Simple -- the ad actually contacts its website in the background, and the site returns a response code that tells it whether to display the popup or not - 'popup=1'. My guess is that kpremium.com returned 'popup=0' while the ad company were testing the ad for conformance to guidelines, and then they turned it back on once it was out in the wild.

I've had a couple of questions by email that I should answer (note I've paraphrased some of these):

What fonts should I use for my HTML Media Center application and can I use Flash?  The SDK is where to go for design guidelines for HTML applications (the short answer is to use a sans serif font).  Yes, Flash can be used in HTML Media Center applications - Napster and MSN Music both use Flash.

How can I add an application to the Start Menu?  You can't.  Well OK, you can, but we recommend that only OEMs use this functionality as there is a limit to how many applications can appear on the start menu and adding a new app will stomp on existing applications.  If you intend to distribute your application you shouldn't do this, but if you really want to know, the details are in the SDK here.

I've seen the Media Center software for sale online is it OK to buy it?  I'm no lawyer so I'm not going to comment on this.  Media Center is an OEM product and only available with new PCs is the official answer though.

Lately I've been working on ‘Den’ and other things relating to the E programming language.

A Core Calculus for Scala Type Checking, is a new paper by the Scala team.

Abstract. We present a minimal core calculus that captures interesting constructs of the Scala programming language: nested classes, abstract types, mixin composition, and path dependent types. We show that the problems of type assignment and subtyping in this calculus are decidable.

The paper revolves around the question of decidability of type checking in Scala. The following quote summarizes the background of this question.

Scala’s approach to component modeling is based on three programming language constructs: modular mixin composition, abstract type members, and explicit self-types. All three have been studied in the vObj calculus. A key concept of the vObj calculus, path-dependent types, is also present in Scala. However, some other constructions of vObj do not correspond to Scala language constructs. In particular, vObj has first-class classes which can be passed around as values, but Scala has not.
First-class classes were essential in establishing an encoding of F<: in vObj, which led to a proof of undecidability of vObj by reduction to the same property in F<:. However, since Scala lacks first-class classes, the undecidability result for the calculus does not imply that type checking for the programming language is undecidable.

Ehud: Given current interest in Scala and its more or less unique (don't want to raise controversy here) position as being both a functional and an OO language, furthermore being much more than a toy language, would it be a good idea to give Scala a place in the Spotlight section?

Event-Based Programming without Inversion of Control. Philipp Haller and Martin Odersky.

Scala is different from other concurrent languages in that it contains no language support for concurrency beyond the standard thread model offered by the host environment. Instead of specialized language constructs we rely on Scala's general abstraction capabilities to define higher-level concurrency models. In such a way, we were able to define all essential operations of Erlang's actor-based process model in the Scala library.

However, since Scala is implemented on the Java VM, we inherited some of the deficiencies of the host environment when it comes to concurrency, namely low maximum number of threads and high context-switch overhead. In this paper we have shown how to turn this weakness into a strength. By defining a new event-based model for actors, we could increase dramatically their efficiency and scalability. At the same time, we kept to a large extent the programming model of thread-based actors, which would not have been possible if we had switched to a traditional event-based architecture, because the latter causes an inversion of control.

(There's not really a proper abstract. The above is from the conclusion.)

I enjoyed this paper. It's a quick read and a nice demonstration of some of Scala's cool features. It's also a good example of using exceptions as delimited control operators, and in fact the one substantial restriction is imposed by the lack of the more powerful operators. They use Scala's type system to reduce the burden of this restriction, however, since they're able to state that a particular statement never returns normally (and thus must not be followed by more statements).

Those interested in the language/library boundary will also find it interesting for this reason:

The techniques presented in this paper are a good showcase of the increased flexibility offered by library-based designs. It allowed us to quickly address problems with the previous thread-based actor model by developing a parallel class hierarchy for event-based actors. Today, the two approaches exist side by side. Thread-based actors are still useful since they allow returning from a receive operation. Event-based actors are more restrictive in the programming style they allow, but they are also more efficient.

They have some fairly impressive empirical scalability results as well.