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Archive for January, 2007

Comments policy

I really appreciate comments to my posts, however as time has gone on there are some guidelines I feel I need to make clear. I have been applying this policy to comments posted on here, and so I felt I should let you know what I’m doing. I will apply these rules on a case by case basis. I have also posted this on my About page.

If a comment is totally off topic (ie. not even tangential to what’s being discussed) I will delete it. Please make your comments and any links you include in your messages have some relevance to what’s being talked about.

I reserve the right to remove website links (entered in the “Website” box of a comment) from comments if they link to sites that appear to be totally or mostly commercial, have no discernable non-commercial content, and in addition have no relevance to what’s being discussed. To me this is as bad as posting spam. This isn’t to say that any time you include a link in a comment it should be non-commercial. You may include commercial links in your messages if they are relevant to the discussion.

If you have a homepage that talks about what you’re up to, your hobbies, etc., or have a blog where you talk about current events, your interests, etc., feel free to put it in the “Website” box of your comment. In this case it doesn’t have to be relevant to the discussion. I’m not going to be a stickler if you have a few ads on your site either.

In short what I’m trying to prevent are people putting links on my blog that go to pages full of ads and hardly anything but ads that have no redeeming value other than trying to generate revenue from page views, clicks, etc. If you’re not doing that then you have nothing to worry about. If you’re the owner of a site such as what I describe, feel free to post a comment, but please leave off the link to your website.

Thanks

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I saw this on Mary Jo Foley’s blog today: ASP.Net AJAX has been released. This is the add-on to ASP.Net 2.0 which was formerly known as “Atlas”. It’s a combination of .Net code (on the server) and Javascript code (on the client) that allows you to set things up in your .Net code, and not have to write a line of Javascript. It may have some add-ons for the Visual Studio designer as well, but I’m not sure. I haven’t looked at it.

Background 

AJAX has had a long history, 10 years in fact. It’s my understanding that it all started with IE4 in 1997. It introduced a Javascript method called XMLHttpRequest(). This is what made AJAX possible. One of the earliest AJAX applications, before Google Maps, was a web add-on for Microsoft Exchange Server, called Outlook Web Access, or OWA. It reproduced the look and feel of Microsoft Outlook (pretty much) in a web browser.

Whenever a traditional web application needs to update a page, it does what is called a “round trip” to the server. The entire page is sent to the server, and then a whole new page is sent back. You will often see the whole page refresh in the web browser screen. This typically happens when you click on a link or a button in the browser window. This is not a very efficient use of network bandwidth, particularly if the change is small. Depending on the speed of the network and the server the browser is communicating with, this process can also be slow. It’s reminiscent of the way old mainframe terminals used to work, except that they were completely text-based.

AJAX is a method by which a client web page can make an asynchronous request to a server, and receive a response back, without having to use the “round trip” method. This is done using Javascript on the browser. The Javascript code takes the response and uses it to update just the part of the web page that needs to be refreshed.

It’s a hack. Some might even call it a kludge. For those not familiar with this term, I believe it goes back a long ways. A “kludge” is when you use something in a way that is contrary to its design or intended purpose, but works anyway. The XMLHttpRequest() call enabled AJAX, but the Javascript language and the browser were not adapted to this new way of doing things. Instead the Javascript call was added, some code was added to the browser to make the call work, but nothing more was added to the browser that would’ve made AJAX make more sense.

I’ve seen some descriptions of how AJAX typically works, and it’s loopy. Anyone who believes in software engineering as a discipline recoils in horror at it (okay, I exaggerate a little). It’s very messy. Making AJAX cross-platform is even more of a challenge, because not all Javascript calls work on all browsers. This is the reason that ASP.Net AJAX and other such frameworks are nice, because you can work with a more familiar language, like C# or VB.Net, work with a nicely constructed framework, set things up the way you want them on the server end, and the framework takes care of sending the right Javascript to the browser at the right time to get the job done so you don’t have to worry about it. You can get the benefits without having to “get your hands dirty”.

Where things stand now 

Right now AJAX and Flash (and technologies that work with it) are the future of web development. WPF from Microsoft was released earlier, but in the eyes of one expert who has done application development for many years it’s not ready for prime time yet. I went to a presentation on WPF last night by Rocky Lhotka, and the sense I got of it is it’s nice for creating web-like applications that have a multimedia focus, but it’s not ready for anything serious in the realm of business applications yet. It would be alright to use for simple applications that need only simple form input. Anything more sophisticated than that, and you’re looking at a headache. The way WPF works is not that much different than the way a web browser works at this point. I’d put it at the level of IE 1.0 or 2.0. It allows some logic to be used on the client side, but it doesn’t allow the flexibility of Javascript in a browser. Rocky said it might be another 2-4 years before WPF is up to the level of Windows Forms. He predicted that it’s the future of rich client development, but it’s not that great to work with yet.

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