If we are asked to do most of suction iPod) they are cool and they are all very innovative projects. 

  Whether these aside, Web designers to design interactive Web there is no better way, yet we do desktop software for colleagues to look a little envy. Desktop applications with rich interface, as well as procedures for the Web incomparable responsiveness.    Similarly, the rapid development of Web, we are providing the experience and users from the desktop applications received by the experience of a tremendous gap between the 

  Today, the gap is disappearing.    Please look at the "Google recommendations (Google Suggest)." Observe it according to your input demonstrate that the proposed rate entries updated almost immediately updated.    Let us look at the "Google Maps." Enlarge, using your mouse moving and rolling.    These moves respond almost immediately, not waiting for the updated pages. 

  "Google Suggest" and "Google Maps" is used Ajax technology of the two typical examples.    Ajax Asynchronous JavaScript and XML is short, it demonstrated a Web development of the fundamental changes, that is, on the Web could do. 

  Ajax definition 

  Ajax is not a technology, it is actually several technologies, each of which has its own unique technology, together have become a powerful new technology.    Ajax include: 

•   XHTML and CSS 
•   Using Document Object Model (Document Object Model) for the dynamic Display and interactive 
•   Using XML and XSLT to data and interactive operation 
•   Use XMLHttpRequest to receive asynchronous data 
•   They will use JavaScript bundled together 

  Traditional web application model to work like this: most of the user interface actions trigger a link to the Web server HTTP request.    -- The completion of some servers receive data processing, handling, longer have access to other database systems, the final return of an html page to the client.    This is an old-fashioned model, the introduction of the use of hypertext as a web has been used all this, but read "The Elements of User Experience" readers will be aware that what is not restricted Web interface desktop software so useful. 

  Figure 1: Traditional Web Application Model (left) compared with the Ajax model (right). 

  The old ways Let us recognize that the many technical, but it will not have a very good user experience.    When servers are dealing with their own affairs when users do?    Yes, wait.    Every action, users must wait. 

  Obviously, if we are thinking on the design of desktop procedures Web application, we do not want to always wait for the user.    When loading interface, why should allow users to spend half of each of the services take time from the data?    In fact, why keep procedures to allow users to see data from the server? 

  How to cut Ajax 

  By users and the introduction of a server between Ajax engine, the Web can be eliminated beginning - stop - start - stop this interaction process. Increase it as a mechanism to the process, making it more sensitive response, and it is indeed done this point. 

  Unlike loading a page, as in the beginning of the session, a browser add-ons - Ajax engine using JavaScript and often prepared in a hidden frame in.    This engine is responsible for mapping user interface and communication with the server.    Ajax engine allows users asynchronous way to achieve interaction with the process - not waiting for server communications.    Therefore, users do not have to not open a blank window, waiting for the cursor to see constant change, then wait for the server to complete response. 

  Figure 2: traditional interactive Web application synchronization process (1) and Ajax application of asynchronous interaction process comparison (2). 

  Usually result in a HTTP request to the user's movements through JavaScript now called Ajax engine instead. Any user action no longer require a direct response to a server - such as simple data validation, editing data in memory, and even some pages --- navigation engine can handle it on their own. if the engine needs from data from the server to respond to a user's movements - assuming it to the need to deal with the data contained in another interface code, or receive new data - engine These asynchronous, usually using XML, they do not have to担misuse of the interactive user interface. 

  Who in the use of Ajax 

  Ajax used in the development of the above, Google done a great investment.    Last year, Google all the major products with this technology - Orkut, Gmail, and the recent beta version of the Google Groups, Google Suggest and Google Maps - All are Ajax applications.    (For more of these Ajax actual technical details, see their article: Gmail, Google Suggest, Google Maps). Other like: Flickr, many people like to use the Ajax features, and Amazon's A9.com Search engines use a similar technology. 

  These projects prove that Ajax is not just academic, there are many successful real-world applications.    This is not a laboratory technology.    Ajax application can be more or less, from the very simple, such as single-function of Google Suggest to a very complex Google Maps.