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Mastering Ajax Websites
An anonymous reader writes to tell us that IBM DeveloperWorks has an interesting article introducing the uninitiated to the world of Ajax. From the article: "Ajax, which consists of HTML, JavaScript technology, DHTML, and DOM, is an approach that helps you transform clunky Web interfaces into interactive Ajax applications. The author, an Ajax expert, demonstrates how these technologies work together. Ajax is more than just the latest fad -- it's your stepping stone to build better Web sites through efficient use of your time."
. . . how when a new fad comes along, people say it's not a fad?
I too have felt the cold finger of injustice.
A nice example of Ajax usage can be found at http://www.meebo.com/.
AJAX isn't an end in itself; it's just a tool. It's like JavaScript. Back when the web was old, if you wanted to do data validation for a form (for example), you had to send the page to the server and wait for a new page as a response. When JavaScript became popular and well-enough supported, the webpage itself could check data before sending it to the server - although the checks couldn't be that complicated. AJAX is similar; instead of limiting yourself to either using a new page or client-side data, AJAX lets you use JS to access server-side data.
As a concrete example, play with Google Maps for a couple of minutes, then try using a map from MapQuest. It will quickly start to annoy you that you can't drag the map and that you have to click to a new page to move the map around. GMaps isn't pure AJAX, admittdly, since it deals with picture data - it can just write the image tags to the page and move them around as you drag. But the side text and the map searches are AJAX - when you click search, you don't open a new page with the search results. You can keep using the map; the client will turn your search into an XML request, Google will process it, and send the results back as XML - asynchronously.
For another example, I wrote this week a dead-simple chat program (because I needed a specific feature). It was simpler to write a web app instead of a real app, because the latter would require networking, windowing, and whatnot - the web interface made GUI easy and manual networking irrelevant. Without AJAX, I would need to have the page reload every second to check if there are new messages - very distracting. I had the system asynchronously check for messages in the background, and when one arrived, update just that part without refreshing the page.
AJAX is a tool to be used when necessary. Don't freak out over it, but realize it's there whenever you need to use a more application-like interface instead of a page-like interface.
AJAX doesn't make it easy to develop cross-platform web applications. Look at all the browser incompatibilities in the developing of Gmail and more recently MSN's start.com page.
We need to re-standarize Javascript or at least make sure all the browsers implement a 100% compatible version. And I don't think that will work since not even HTML is properly rendered by any browser at all.
Well, as soon as we get all of the web browsers out there to adopt your so called "new language", we'll be all set. Your comment about Macromedia Flash made me laugh. Explain to me how Action Script interacting with the server with XML.send() is any different than JavaScript using XMLHttpRequest??
Obviously you're not a web developer ;)
Instead, how about a JavaScript 2.0? The language is only short a few key elements (like a native JSON serializer).
I started developing web based applications 7 years ago. At that time, JavaScript was really only useful for image mouse overs and was more or less useless and I refused to use it for anything.
Well, about 8 months ago I decided to give JavaScript another chance. All I can say is, wow it's come a loooong way.
I'm a bit skeptical of all of the frameworks that have popped up. They seem to overcomplicate things profoundly. I've looked at a lot of them, but haven't decided that any of them are less work than the solution I developed on my own.
My approach is to use JSON instead of XML. I have a server side script (can be any language, I used PHP for my last application) which acts as a listener script. The listener script accepts and sends JSON strings. The client JS composes and sends JSON strings with XMLHTTP request.
It's clean, fast and simple to maintain and expand. I think these claims of AJAX being "too complex" are ridiculous.
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Not trying to spruik it or anything, but I'm currently working on a project of making a webapp using Laszlo.
It's an open source language/server for creating flash based applications.
We've found it to be very impressive how much you can do with so little code... and it's nice to have a proper OO backend to a flash frontend... the flash frontend means we can:
a) Make our interface very pretty and like a 'normal' application
b) Means it works in pretty much any browser...
c) on pretty much all platforms...
d) without a download of any plugin in most cases (just because of the penetration of flash)
I've been working on a project that provides a web-based environment for people with a medical condition to get counseling and support online. Chat has been one of the desired features, but the various methods for implementing chat were presenting a problem. Java applets and Flash applications presented problems with time to load for modem users as well as issues with having the right versions of Java/Flash player installed on client. I thought setting up a Jabber server and letting folks use a client installed on their computer would be a good solution, but many (most) found it too difficult to install and configure a chat client. (These are older folks often with little computer experience.) AJAX came to the rescue. The "chat client" is part of the web application. It is as lightweight as the typical web pages being loaded. The exchange of messages between client and server require very little bandwidth. The chat application is just part of the same environment that the users are already comfortable using. I don't see AJAX as the answer to everything and, for the moment, having web applications chock full of AJAX doesn't make sense. But, it has come in very handy in the case of chat for the project I am working on.