AJAX (asynchronous JavaScript and XML) isn't a new technology. Rather, it's a method of using several existing technologies -- including CSS, JavaScript, XHTML, XML, and XSLT -- to develop Web applications that look and act like desktop software. Jesse James Garrett, director of user experience strategy and a founding partner of Adaptive Path, coined the term in a paper he published on the Adaptive Path Web site in February.
The term asynchronous refers to the way AJAX applications communicate with their host servers. Under the old model, the Web browser refreshes the current window each time a user performs some action that initiates a request for new data from the server.
Under AJAX's asynchronous model, the browser doesn't have to wait for the user to request an action, nor does it have to refresh the entire window to show newly retrieved data. Instead, the JavaScript code running in the browser communicates with the server by passing XML-formatted data back and forth. The JavaScript code can also apply style sheets to retrieved data and display it in one portion of the existing Web page.
Among consumer-facing applications, Google's Gmail and Google Maps services are the most common examples. In Gmail, AJAX is responsible for the way threaded conversations slide open to reveal the text of different messages. In Maps, it allows users to drag and scroll across a map in a seemingly seamless fashion.
Garrett also points to Yahoo's Flickr photo sharing application and Amazon.com's A9 search engine. And it's likely that Yahoo's new Web-mail service, based on technology it acquired with the purchase of Oddpost, will soon get plenty of attention from AJAX proponents.
Increasingly, however, AJAX application vendors are looking to the enterprise. For instance, Scalix's Web Access e-mail application actually resembles Microsoft Outlook more than Outlook's own Web-mail interface.
But there are some limitations on where AJAX applications will work. Because they make use of some of the latest Web technologies, they will run only in certain Web browsers -- the list, however, is expanding.
This whitepaper explains the terminology and concepts behind Data Replication technologies and establishes some sizing rules through worked examples. Learn the new paradigm in disaster tolerance—protect data anywhere.
Download now »
Server virtualization is a popular option for dealing with mounting datacenter costs. Another equally promising approach is the use of an Application Delivery Controller. Citrix NetScaler provides a low-cost way for organizations to reduce their server count and accrue cost savings from a reduction in space, cooling, power and personnel.
Download now »
The emergence of WLANs has created a new breed of security threats to enterprise networks.
Included in HP ProCurve WLAN solutions is security technology that alleviates threats from WLANs through:
* Monitoring wireless activity inside and out of the enterprise
* Classifying WLAN transmissions into harmful and harmless
* Preventing transmissions that pose a security threat to the enterprise network
* Locating participating devices for physical remediation
Effectively address data protection challenges, implementing solutions that help store and protect business–critical data while cutting costs and improving efficiency and reliability.
Download now »
Sign up to receive InfoWorld Resource Alerts
Recommend This
