What is AJAX, really?

Question

I have to start using AJAX in a project and I don't know where to start. Can someone please help?

Answer 1

http://en.wikipedia.org/wiki/Ajax_(programming)

Answer 2

http://www.w3schools.com/Ajax/Default.Asp

that is a good place to start. This should answer all of your questions.

Answer 3

Asynchronous JavaScript And Xml. A technique for achieving bi-directional, script-driven communications between Web browsers and servers via HTTP.

See also:

• definition on Wikipedia
• AJAX Introduction on w3schools
• Ajax Workshop 1 on Ajax Lessons

Edit: As pointed out by Nosredna, JSON is often used in place of XML.

Answer 4

Not to be confused with the cleaner, AJAX, the technology term, is really describing a framework or better stated as a technique for using XML and JavaScript to make asynchronous calls to server side code...

Here are some good code samples. And some more.

While many of these samples above show how to create all of the XML Request objects, if you look into the AJAX Control Toolkit from Microsoft for ASP.NET applications or jQuery, you'll find these easier to work with.

jQuery Sample (from jQuery site):
when code is hit, the some.php file is hit passing the name and location values in.

    <script type="javascript">
        function saveDataAjax(){ 
        $.ajax({
           type: "POST",
           url: "some.php",
           data: "name=John&location=Boston",
           success: function(msg){
             alert( "Data Saved: " + msg );
           }
         });
       }
   </script>
   <input type="submit" onClick="saveDataAjax();" value="submit" />

Answer 5

It's JavaScript, but it works.

Answer 6

From the man that coined the term - http://adaptivepath.com/ideas/essays/archives/000385.php

Answer 7

I believe the fastest and easiest way to get started is with jQuery:

http://jquery.com/

http://docs.jquery.com/Ajax/jQuery.ajax#examples

Answer 8

AJAX stands for asynchronous JavaScript and XML, though it doesn't always deal with XML data anymore. Essentially it boils down to using the XMLHttpRequest object through JavaScript running on the client to make a web request and retrieve some information that you use to update the state of your page without requiring a page refresh.

Start with a basic tutorial that shows you how to use bare bones Ajax to make asynchronous requests such as http://www.w3schools.com/Ajax/Default.asp before moving on to using it in a production level application.

When using it in an application you're far better off investigating one of the common JavaScript frameworks that abstract away the differences between the various browsers and make it easy to manipulate the page after the request returns. I personally recommend http://www.jquery.com/

Answer 9

"Ajax" is the successfull marketing term introduced back in 2005 to replace the the older term "DHTML" that did not stick well. "Ajax" today is part of the history too as the new word - "HTML5" emerge. Still "HTML5" is pretty much what original "DHTML" used to be.

Ajax is also reffered to as "the new approach to the application development" where a web page is created on the server initially but later on, during its lifetime, the updates are being done on the client as the data or partial content gets communicated to the server in a background.

Hope this clarifies.

Answer 10

The rough idea in English:

You have a web page. Some event (can be a button press or other form event, or just something triggered by a timer) occurs and triggers JavaScript code that asks the server for fresh information (like the latest value of GOOG stock).

There's a piece of code on the server that collects the info you passed and sends some info back. That's different from the page-serving job the server usually has.

When the server answers, a callback function (that you specified in the JavaScript call to the server) is called with the info from the server. Your JavaScript code uses the info to update something--like a GOOG stock chart.

Answer 11

I read Head First AJAX as my first AJAX reference and I found it to give a simple and practical overview of AJAX.

Answer 12

Most commonly, it refers to the use of the XMLHttpRequest object via JavaScript* in a browser.

Depending on who you ask, it could be used to describe almost any type of client/server communication over HTTP other than just typing a URL into a browser.

*jQuery provides some nice wrapper code to handle cross-browser differences, etc.

Answer 13

Creative use of previously known technology. Both the browser side scripting and programmatic access to data on the server have been known before. In AJAX it has been put together for innovative use anabling new applications of thechology known before. The REST comes to mind as similar type of advance...

Answer 14

AJAX is very simple : someone somewhere tought that it would be cool to be able to send something to the server and receive something from it without reload a page.

AJAX is not a revolution, it's just a name for something simple : a web page can send a request to the server without being reloader - just some asynch stuff here.

You can add AJAX controls on your web pages wihout any works - just drag them in with Visual Studio. You may have to add some manager for them, but it is simply a drag-and-drop task.

But be warned : rogue web browser usually don't speak the same AJAX language as IE...

:)

Answer 15

Just to add.. may be not relevant for the question .. although, AJAX was made famous by Gmail in their browser emails ..the credit of AJAX goes to Microsoft .. they created the AJAX thing..

Answer 16

Ajax is a bit of a misnomer. To quote the wiki article:

Despite the name, the use of JavaScript and XML is not actually required, nor do the requests need to be asynchronous.

Whereas now most people call "ajax" any type of

web application that communicates with a server in the background

Answer 17

From the Pragmatic Ajax book:

What Is Ajax?

Ajax is a hard beast to distill into a one-liner. The reason it is so hard is because it has two sides to it:

• Ajax can be viewed as a set of technologies.
• Ajax can be viewed as an architecture.

Ajax: Asynchronous JavaScript and XML

The name Ajax came from the bundling of its enabling technologies: an asynchronous communication channel between the browser and server, JavaScript, and XML. When it was defined, it was envisioned as the following:

• Standards-based presentation using XHTML and CSS
• Dynamic display and interaction using the browser’s DocumentObject Model (DOM)
• Data interchange and manipulation using XML and XSLT
• Asynchronous data retrieval using XMLHttpRequest or XMLHTTP (from Microsoft)
• JavaScript binding everything together

Although it is common to develop using these enabling technologies, it can quickly become more trouble than reward.

It is for these reasons that the more important definition for Ajax is...

Ajax: The Architecture

The exciting evolution that is Ajax is in how you architect web applications. Let’s look first at the conventional web architecture:

1. Define a page for every event in the application: view items, purchase items, check out, and so on.
2. Each event, or action, returns a full page back to the browser.
3. That page is rendered to the user.

This seems natural to us now. It made sense at the beginning of the Web, as the Web wasn’t really about applications. The Web started off as more of a document repository; it was a world in which you could simply link between documents in an ad hoc way. It was about document and data sharing, not interactivity in any meaningful sense.

Picture a rich desktop application for a moment. Imagine what you would think if, on every click, all of the components on the application screen redrew from scratch. Seems a little nuts, doesn’t it? On the Web, that was the world we inhabited until Ajax came along.

Ajax is a new architecture. The important parts of this architecture are:

• Small server-side events: Now components in a web application can make small requests back to a server, get some information, and tweak the page that is viewed by changing the DOM. No full page refresh.

• Asynchronous: Requests posted back to the server don’t cause the browser to block. The user can continue to use other parts of the application, and the UI can be updated to alert the user that a request is taking place.

• onAnything: We can interact with the server based on almost anything the user does. Modern browsers trap most of the same user events as the operating system: mouseovers, mouse clicks, keypresses, etc. Any user event can cause an asynchronous request.

This all sounds great, doesn’t it? With this change we have to be careful, though. One of the greatest things about the Web is that anybody can use it. Having simple semantics helps that happen. If we go overboard, we might begin surprising the users with new UI abstractions. This is a common complaint with Flash UIs, where users are confronted with new symbols, metaphors, and required actions to achieve useful results.

Answer 18

It's a buzzword, the essence of it is:

Using Javascript to make an asynchronous HTTP request (in the background).

When the content arrives, an action is taken, usually performing some logic then updating the appearance of the page by manipulating the DOM tree; meaning, inserting new HTML elements, deleting some html elements, etc.

The X in AJAX stands for XML, but it's irrelevant. XML is just one of many ways to format the data that's sent by the server. JSON is a much better alternative (IMNSHO). Also, the server can send plain text or just regular html.

The keyword here is asynchronous request. A request that happens in the background, without the browser having to reload the page.

Answer 19

It's a cleaning product.

It also stands for something very cool built with a very hateful programming language.

Answer 20

AJAX is really fancy term for giving the browser the ability to refresh parts of its content with the need to reload an entire page. Like many have said, it doesn't require XML, or even Javascript in order to implement it. In fact in its early days it was done with with VBScript and Jscript and just called DHTML. Jesse James Garrett may have invented the AJAX term, but it was really Microsoft that invented the concept behind it.

This source says Microsoft started it in 1999, but I would date the birth of this technology even further. This Wired article is probably more accurate on the date of this technology being in the late 90's, much of it coming from the old days of the MSDN DHTML Dude columns written by Michael Wallent at Microsoft which started back in 1997. Much of the story is also told in this great video here by Michael himself: http://channel9.msdn.com/posts/Charles/Michael-Wallent-Advent-and-Evolution-of-WPF/ Megan still works at Microsoft by the way working on the Silverlight team nowadays, Microsoft's replacement for ActiveX.

Back to the AJAX thingy...when Jesse James Garrett back in 2005 he was mostly talking about the use of XMLHTTPRequest within Javascript code, and a dash of salt. That later began a hip word that many people started using even though they had no idea what it was, and thought that is really something brand new and hip, when really it was just a remix of something old.....sort of like many hip-hop songs you hear nowadays.

It's not new, just a newer version of something old!

Answer 21

I'll give it a try and say that "it's the concept of having a W3C based (JavaScript, HTML and CSS) solution for building Rich Applications for running on the web in a browser"

Everything else is just "technical details" I guess ... ;)

PS! - AMAZING question ...!! ;)