Tutorials Client ServerThere is a gap in user experience between desktop applications and web applications. Desktop applications run on a single computer, while web applications run on the Internet. Since the invention of the Web, developers have been trying to design web applications that demonstrate the speed and interactivity of applications running on the client machine of a LAN (Local Area Network). Despite the explosion of web based applications in the 1990’s (and continuing today), many users still prefer desktop applications. Like web sites, desktop applications access up to date information by connecting to the Web through the Internet.
However, desktop applications are designed with a much more refined sensibility and use PC power to customize requests from information stored on the desktop. This user experience is significantly better than when using remote web sites. Many are arguing that desktop applications will be the next wave in the Internet revolution.
So, with desktop applications breathing down their necks, web applications need to keep up the pace. Web applications are accessed by web browsers and run over a network, like the Internet. They are popular because of the power dominance of web browsers serving as thin clients. The most popular web browsers are Internet Explorer, Mozilla Firefox, Safari, Opera, and Netscape. Thin clients are client applications or devices that simply initiate requests and provide input. They do very little of the processing, letting the server handle the heavy lifting by forwarding requests and contacting different nodes and networks. Web applications are responsible for web based e mail applications like Hotmail, online shopping sites, online auction sites, wikis, and blogs.
In traditional client server computing, every application contained a client program that provided the user interface (UI) through which users would interact with/make requests from the applications. Each client program had to be installed individually on each user workstation. Web applications are different.
Web applications dynamically generate web documents. These are HTML/XHTML (Hypertext Markup Language/Extensible Hypertext Markup Language) documents transmitted over the Internet through HTTP (Hypertext Transfer Protocol). These documents or pages make up the web site. Using a standard server side scripting language like JavaScript allows for more interactive features in the user interface. Usually, each page is delivered as a static document, but the sequence in which they are presented is interactive. User web forms are embedded in the page markup, customizing responses. The web browser, acting as “universal client”, interprets and displays the dynamic web pages.
This article will be discussing the role of Ajax in user experience, which is conducted through the interface. Web application UIs offer a variety of features. For example, the drag and drop feature allows for virtual objects to be moved from location through the mouse. This can create all sorts of actions, from copying to associating two objects to create a new action. By using application specific technologies like Java, JavaScript, DHTML (Dynamic HTML), and Flash, all sorts of graphic and audio interactive features may be added to a UI. As previously stated, web developers are currently looking for ways to improve user experiences with web applications so they more closely resemble the performance of desktop applications. Remember, the user experience is most often gauged by the usability of the UI or GUI (Graphic User Interface). Ajax is one of the technologies that is helping achieve that.
Ajax itself is an acronym for Asynchronous JavaScript and XML. It contains two pre existing technologies and an information loading technique. They were brought together to create a friendly web experience. In this constellation of technology, XML is used to describe, store, and move information between clients to servers. JavaScript binds these elements together dynamically. ‘Asynchronous’ describes the information loading technique Ajax uses. It is described as such because when any changes must be made to the current page (for example, by clicking on a link or entering some information), only the part that needs to be changed is delivered from the server. The entire page doesn’t have to be re loaded, which reduces latency.
Ajax contains a whole host of other characteristics as well. It is also sturctures the way information is displayed by using HTML and CSS. By using these two technologies, Ajax ensures that the browser will understand content and formatting. Ajax also uses XML and XSLT (Extensible Stylesheet Language Transformation). XSLT allows XML documents to be converted into other XML documents. It’s part of XSL, the stylesheet language of XML. It is used to retrieve web pages from dynamic data sources and processes them for final output so they are ready to be displayed. JavaScript objects and XMLHttpRequest get information from the server and the user’s browser.
The dynamic object model (DOM) allows for the dynamic modification of the information retrieved. It alters the properties of already existing page elements to make static web pages dynamic. These instructions are accomplished by JavaScript, which is also the glue that binds all these elements and activities. JavaScript is a client side scripting language that retrieves dynamic content, modifies page elements, and displays dynamic web pages.
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