Ajax
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  • AJAX stands for Asynchronous JavaScript and XML, and is a web application that is responsible for such things as the list of suggestions that drop down as you enter text into a Google search box or the ability to zoom in and out in Google Maps, all without reloading the entire page.
  • AJAX applications can be any size, from the very simple, single function application to the complex and sophisticated. It also is constantly in development and being refined to incorporate new applications or technologies. For example, despite the XML in the AJAX name, it is not necessarily needed, and JavaScript Object Notation (JSON) is often used instead. In addition, VBScript can be used instead of JavaScript as a client-side scripting language in an AJAX application. The requests sent between the user and the server also do not have to be asynchronous for an AJAX engine to work. It all depends on the need and function of the page.
  • The AJAX model gives the user the feeling that changes are instantaneous and the user is much more responsive as only small parts of the page are transferred at a time.
  • User waiting time is reduced with the AJAX engine, only relevant content changes, as needed, and the user can still work within a page while the data is being submitted. If a section of a page encounters an error, no other sections of the page are affected, and the user will not lose any data.

Ajax Ajax Presentation Transcript

  • Geek Speaker: Veronica NettCOM 585 – Fall 2011Nov. 2, 2011
  • AJAXAJAX stands for Asynchronous JavaScript and XML, andis a web application that is responsible for such things asthe list of suggestions that drop down as you enter textinto a Google search box or the ability to zoom in and outin Google Maps, all without reloading the entire page.
  • THE LITTLE ENGINEAJAX utilizes several different web-based technologiesand standards to create an intermediary – an AJAXengine – between the user and the server. While a userbrowses a webpage, the AJAX engine communicates withthe server in the background, updating parts of thewebpage without interfering with the entire page andmaking the user wait while it reloads.An example is Gmail. An AJAX engine checks and addsnew mail as it comes in, without reloading the page.
  • AJAX: A NEW APPROACH TO WEB APPLICATIONS ―Ajax isn’t something you can download. It’s an approach—a way of thinking about the architecture of web applications using certain technologies.‖ -- Jesse James Garrett, Chief Creative Officer of AdaptivePath.com, and the man generally considered to have coined the term AJAX in 2005.
  • IN A NAMEAJAX refers to two technologies (JavaScript and XML)and a technique (asynchronous) for loading information.But it incorporates so much more.
  • TECHNOLOGIESAJAX incorporates:• XHTML and CSS are standard languages that browsers understand and are used to present information to the user. XHTML for content and CSS for layout and formatting.• XML and XSLT describes information and distributes it in a platform- independent format. XML is used for the interchange of data from a dynamic data source, and XSLT to process and manipulate it for final output on the webpage• Document Object Model (DOM) allows programs to access and update the content, structure and style of a document once it is displayed. This allows the user to interact with the content presented, such as greying-out a button once certain information is entered.• Asynchronous -- being independent of communication with a server – data retrieval using XMLHttpRequest is when a change is made to a page (the user zooms in on a section of a map). Only the part of the webpage to change is transferred from the server, and not the entire page• JavaScript is the glue that holds all the elements together. JavaScript is a programming language used to perform various tasks, and binds all the AJAX technologies.
  • BROAD GROUP OF TECHNOLOGIESAJAX applications can be any size, from the verysimple, single function application to the complex andsophisticated. It also is constantly in development andbeing refined to incorporate new applications ortechnologies.
  • ADDING A LAYERThe basic building blocks of AJAX were introduced in the1990s, when most websites were based on completeHTML pages. Every user action on a webpage, requiredthe page to be re-loaded from the server – all the contentre-sent instead of only the changed information --causing a start-stop-start-stop experience for the user.
  • THE HTML MODEL
  • THE HTTP MODEL
  • THE AJAX ENGINEInstead of loading a webpage, the browser loads an AJAX engine –written in JavaScript and usually tucked away in a hidden frame. TheAJAX engine is responsible for both rendering the interface the usersees and also communicating with the server on the user’s behalf.With the AJAX engine, a webpage is loaded entirely only once. Everyuser action takes the form of a JavaScript call to the AJAX engine. Thisallows for the users interaction with the webpage to happenasynchronously – independent of communication with the server –keeping the user from having to stare at a spinning color wheel orhourglass icon.
  • AJAX USER MODEL
  • A SMOOTH APPLICATOR
  • BUILDING BLOCKSAsynchronous loading of content first became practical in 1995 whenJava applets were written into the first version of Java language. Theapplets collect user data, such as mouse input, buttons and checkboxes, and load data asynchronously from the server after a page hasbeen loaded.Internet Explorer introduced the iframe element to HTML in 1996, whichalso enabled asynchronous loading. It took off in 1999, when Microsoftused the iframe technology to update news stories and stock quotes onthe default page of Internet Explorer. That same year, Microsoft createdthe XMLHTTP Active X control in Internet Explorer 5. The programingwas adopted by Mozilla, Safari and Opera as XMLHttpRequestJavaScript, which is commonly used in today AJAX applications.
  • FULL SCALE ONLINE APPLICATIONIn 2000, Microsoft filed a patent on the basic AJAX technology.AJAX began to gain widespread use in 2000, when it was applied toOutlook Web Access and then Oddpost in 2002. It became a webstandard in 2004 when Gmail adopted the application, and then in2005, with Google Maps.
  • REFERENCES• Ajax (programming) http://en.wikipedia.org/wiki/Ajax_(programming)• Ajax: A New Approach to Web Applications http://www.adaptivepath.com/ideas/ajax-new-approach-web- applications• Beginning Ajax http://www.wrox.com/WileyCDA/Section/What-is-Ajax- .id-303217.html• Why use Ajax? http://www.interaktonline.com/support/articles/Details/AJAX%3A+Async hronously+Moving+Forward-Introduction.html?id_art=36&id_asc=306• A Brief History of Ajax http://www.aaronsw.com/weblog/ajaxhistory