How can I decide if a website is using Ajax technology? What are the characteristics that I should I look in the website to tell it is an ajax application?
Search the javascript for XMLHttpRequest. Beyond that, the working definition of Ajax is rather too broad to look for, say, specific behaviours.
You can just look into the javascript source code and search for .ajax, .post and .get . If you find any of these they use ajax technologies.
You can also look at the network requests a page sends, if the page sends requests after loading the full page without you seeing it refreshing it probably uses ajax.
There's nothing special about websites using AJAX, it just means they make an asynchronous call to the server at some point. You can't know for certain that the website will make such a call unless you run it.
From my understanding, AJAX requires the use of the XMLHttpRequest object. What I am confused on is the source of where the XMLHttpRequest object is connected to? In the school projects, I have connected it to XML and mySQL and was told that I am doing AJAX. What if I connect the XMLHttpRequest object to a PHP script which contains an array of data? Would that count as AJAX?
The reason why I ask is because I was thinking of adding AJAX to my resume, but since this area seems so broad and I have had limited experience with it, I want to make sure I have a clear understanding of this technology.
The AJAX part is just how the request is made from the client. If it happens asynchronously using XmlHttpRequest, it doesn't matter where the request is going :-) It could be a request to an server side script in PHP, a JSON file, an xml file, or anything else.
It's not broad at all. Any time you do an async web request (actually, it doesn't even have to be async, but that's really the best way to to use it) via javascript (rather than through a Form submit) you're using AJAX. What you connect to or what you retrieve is irrelevant.
Without being rude, I'd like to point out that if you state on a resume that you possess "a clear understanding of this technology" then you're not being honest, since you're asking this question, which indicates that your understanding of the technology isn't "clear".
If, however, you're totally confortable with the use of Ajax and were simply not entirely clear on it's lexical definition... well... now you should be.
yes ,the ajax can used for all language,soever java or asp and php
Is anything that uses JavaScript and asynchronous communication of XML data considered Ajax?
Most people who deal with AJAX would consider any usage of XMLHttpRequest to be AJAX.
This doesn't mean that the request need be async either.
These days, JSON replaces XML for communications.
From wikipedia:
With Ajax, web applications can send data to, and retrieve data from, a server asynchronously (in the background) without interfering with the display and behavior of the existing page. Data is usually retrieved using the XMLHttpRequest object. Despite the name, the use of XML is not needed (JSON is often used instead), and the requests need not be asynchronous.
AJAX seems to encompass any application which retrieves data using the XMLHttpRequest object. Despite it's name you don't need to use XML and I'd wager most AJAX apps these days are using JSON instead. Also they don't necessarily make asynchronous requests. We probably need a new buzzword at this point. Maybe websockets will take off!
The term AJAX and its abbreviation is a misnomer. It has nothing to do with XML. It typically refers to the XMLHttpRequest function. The name of this function again is a misnomer because you could use it to get or send JSON data, plain text, or even binary data now.
AsyncHttpRequest would have been a more appropriate term for the function, and AJAH (Asynchronous JavaScript and HTML) instead of AJAX. On a side note, although XMLHttpRequest allows synchronous requests too, they'd probably be better off getting rid of it altogether.
Typically AJAX applications make good use of asynchronous calls and avoid page refreshes as much as possible. Gmail is a good example. Facebook, on a modern browser, also uses AJAX. Clicking on different links like "News Feed", "Events", etc. doesn't cause a page reload although the path in the address bar changes. Github does the same on modern browsers.
I have a partial template that I want to intermittently poll the server (one of my controllers) and update its display with the result.
What is the appropriate way to do this with grails?
I have seen some articles saying there are specific grails tags for ajax calls, which would be nicer as it would allow clean direction to a controller/method, however, I've not seen anything in Grails to suggest that polling of a controller method could be done altogether.
Thanks!
There's nothing built into Grails that will do the polling for you. The most basic way is to simply use the setInterval() function in your JavaScript. If you're using a JavaScript library then something might be available there that would make things easier on you.
As a side note, be careful when implementing polling. If you're application isn't scaled correctly and you expect a lot of users, polling can bring your system down quickly.
I have to start using AJAX in a project and I don't know where to start. Can someone please help?
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.
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.
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" />
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.
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:
Define a page for every event in the application: view items, purchase
items, check out, and so on.
Each event, or action, returns a full page back to the browser.
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.
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.
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
http://www.w3schools.com/Ajax/Default.Asp
that is a good place to start. This should answer all of your questions.
From the man that coined the term - http://adaptivepath.com/ideas/essays/archives/000385.php
"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.
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..
I believe the fastest and easiest way to get started is with jQuery:
http://jquery.com/
http://docs.jquery.com/Ajax/jQuery.ajax#examples
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/
I read Head First AJAX as my first AJAX reference and I found it to give a simple and practical overview of AJAX.
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...
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...
:)
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!
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 ...!! ;)
AJAX (Asynchronous JavaScript and XML) is a newly coined term for two powerful browser features that have been around for years, but were overlooked by many web developers until recently when applications such as Gmail, Google Suggest, and Google Maps hit the streets.
To know more information about Ajax learn Ajax tutorial
AJAX = Asynchronous JavaScript and XML.
AJAX is a technique for creating fast and dynamic web pages.
AJAX allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page, without reloading the whole page.
Classic web pages, (which do not use AJAX) must reload the entire page if the content should change.
Examples of applications using AJAX: Google Maps, Gmail, Youtube, and Facebook tabs.(FROM w3school). to understand simply: when we request for a link or submit form we request a synchronously to server for data. webpage destroy current page and regenerate new page. but with AJAX browser can send the same request without repainting the entire page.
It's JavaScript, but it works.