The first, Ajax, is the name given to an overall technique
for seamlessly updating portions of a page. The second, Spry, is a specific implementation of Ajax, developed
and released in the public domain by Adobe on their Labs mini-site (http://labs.adobe.com/
technologies/spry).
In this section, you??™ll dive a bit deeper into both Ajax and Spry to better help you understand how the technologies
work and what their uses are.
What is Ajax?
By now, you??™ve probably heard that Ajax is short for Asynchronous JavaScript and XML??”and the key, least
understood, word is asynchronous. An asynchronous action is one that occurs out of the normal sequence.
On the Web, the typical sequence is something like this:
1. The user??™s browser loads a Web page.
2. The user clicks a link on the page.
3. Browser sends the request for linked page to the host computer.
4. The host computer sends the HTML and dependent files to the user??™s browser.
5. The browser displays the page to the user.
These series of steps occur regardless of whether an entirely new page or just a section of the page is
requested in what is referred to as a full-page refresh. One of the key benefits of Ajax is that it enables a
partial-page refresh. Ajax acts as a middleman between the browser and the host computer, requesting only
the data needed, out of the normal sequence.
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