Java Reference
In-Depth Information
A Brief History of Ajax
When the World Wide Web started, web pages contained static content. Any changes to the
content on the page required a full page reload, often resulting in the screen going blank
while the new page loaded. Remember, this was back in the 90s when dial-up modems were
the norm.
In 1999, Microsoft implemented the XMLHTTP ActiveX control in Internet Explorer 5. It
was developed initially for the Outlook web client, and allowed data to be sent asynchron-
ously in the background using JavaScript. Other browsers implemented this technique, al-
though it remained a relatively unknown feature and was rarely used.
Asynchronous loading techniques started to be noticed when Google launched Gmail and
Google Maps in 2004 and 2005 respectively. These web applications used asynchronous
loading techniques to enhance the user experience by changing the parts of the page without
a full refresh. This gave them a much snappier and responsive quality that felt more like a
desktop application.
The term “Ajax” was coined by Jesse James Garrett in 2005 in the article
“Ajax: A New
Approach to Web Applications,”
where he referred to techniques being used by Google in
its recent web applications. Ajax was a neat acronym that referred to the different parts of
the process being used: Asynchronous JavaScript and XML:
Asynchronous
When a request for data is sent, the program doesn't have to stop and wait for the
response. It can carry on running, waiting for an event to fire when a response is re-
ceived. By using callbacks to manage this, programs are able to run in an efficient
way, avoiding lag as data is transferred back and forth.
JavaScript
JavaScript has always been considered a “front-end” language not used to communic-
ate with the server. Ajax enables JavaScript to be used to send requests and receive
responses from a server, allowing content to be updated in real time.
