Synchronous interaction in traditional web applications (top) and heterogeneity in AJAX applications. ( Adaptive Path )
"All user actions will send JavaScript commands to the AJAX processor, instead of creating an HTTP request (HTTP request) and querying to the server," Jesse James Garrett wrote in the first article defined. About this term."If anything is needed from the server, such as downloading additional interface code or receiving new data, AJAX will transfer requests to the server asynchronously, normally using XML, without interrupting the interaction of user with web application ".
Popular AJAX applications
Google Suggestdisplays suggested terms almost immediately when the user has not finished typing the keyword.WithGoogle Maps, people can track changes, move, drag and drop maps like on desktop environments.Google Suggest and Google Maps are two outstanding examples of new generation web application methods.The world's leading search service company has invested heavily in AJAX development.Almost every program they introduced recently, fromOrkut, Gmail to theGoogle Groupsbeta version, are AJAX applications.
Many other companies are also following this trend likeFlickrphotosharing site(currently under Yahoo) or Amazon's A9.com search engine.Yahoo plans to launch Yahoo Mail Beta 1 using AJAX in the next few weeks (currently under limited testing).New mailboxes will be equipped with more features of Web 2.0 such asRSS, preview (preview) . Microsoft is also deployingWindows Live MailandWindows Live Messengerprograms that support AJAX.
These projects show that AJAX is not a far-flung technology but is present in the real world, from a very simple model like Google Suggest to sophisticated and sophisticated like Google Maps.
The biggest challenge when creating AJAX applications is not in the technical stage because its components have long appeared, stable operation and well-known people.The problem here is that "design professionals need to forget the limits of the web, start thinking broader, deeper about the capabilities of technology and create it in their own way", Alexei White, Production director of eBusiness (USA), commented."AJAX will gradually lose Microsoft's influence on the market. Although it is not completely overpowered, it will provide alternative features for most products such as Office."
Disadvantages of AJAX
AJAX can contribute to creating a new generation for web applications (like colr.org or backpackit.com).However, it is also a "dangerous" technology when causing many user interface problems.For example, the "Back" key (back to the previous page) is appreciated in the standard website interface.Unfortunately, this function does not work properly with Javascript and people cannot find the previous content when pressing the Back key.Therefore, only a small mistake is the data on the page has been changed and difficult to recover.This is one of the main reasons why many people do not support Javascript.
Besides, people cannot save web addresses to the Favorite folder (Bookmark) for later review.Due to the application of intermediaries for transactions, AJAX applications do not have a fixed address for each content.This defect makes AJAX easy to "lose points" in the eyes of users.
Browsers that support AJAX are Microsoft Internet Explorer 5.0 and above;Gecko-based browsers such as Mozilla, Firefox, SeaMonkey, Epiphany, Galeon and Netscape 7.1;browser contains KHTML API 3.2 and above such as Konqueror, Apple Safari .
CSS - cascading style sheets (Cascading Style Sheets) - used to describe how to display documents written in HTML, XHTML, XML, SVG, and XUL . Technical specifications of CSS Management of the World Wide Web Consortium (W3C).
DOM - Document object model (Document Object Model) - is an application programming interface (API).Usually the DOM takes the form of a data structure tree and is used to access HTML and XML documents.The DOM model operates independently of the operating system and is based on object-oriented programming techniques to describe documents.
DHTML , or dynamic HTML, creates a web page by combining components: static HTML markup language, client command language (like Javascript) and CSS and DOM format languages.Due to its rich capabilities, DHTML is also used as a tool to build simple games on the browser.