| AJAX Introduction | | | | recommended. As of 2006, CSS Level 3 is still under |
| Ajax is the acronym for Asynchronous JavaScript | | | | development. The main CSS contribution allows a |
| and XML. However, rather than functioning as an | | | | document's style to be influenced by multiple style |
| acronym it better describes a technique for producing | | | | sheets. The cascading effect comes from the ability |
| faster, more interactive, and usable web pages that | | | | of style sheets to 'cascade' from one another, |
| don't require re-loading every time a user changes a | | | | inheriting a stylistic mixture determined by the site |
| request. This is accomplished by increasing web page | | | | designer and user. |
| responsive-ness through the exchange of small | | | | Javascript is a scripting language created to enable |
| pieces of data by an invisible server. | | | | prototype-based programming. It is most popularly |
| The prerequisites of Ajax are a collaboration of | | | | used for web sites. Its only similarity with Java the |
| HXTML (Extensible Hypertext Markup Language), | | | | programming language is its C syntax. Javascript was |
| CSS (Cascading Style Sheets) that help represent the | | | | developed in 1995 and trademarked by Sun |
| markup language, client-sided description languages | | | | Microsystems. It was licensed for use with Netscape |
| like JavaScript, objects like XMLHTTPRequest that | | | | Communications when Netscape began to support |
| allow the asynchronous transfer of data, and the | | | | Java technology in its Netscape Navigator web |
| formatting provided by XML (Extensible Markup | | | | browser. Currently, Javascript also operates for other |
| Language). | | | | entities like the Mozilla Foundation. As of 2006, the |
| Again, Ajax is a technique, not an object. Jesse | | | | latest model of this scripting language is Javascript 1.7. |
| James Garrett coined Ajax in 2005 in a presentation | | | | XMLHTTPRequest object allows for the |
| to clients. The components that make up Ajax | | | | asynchronous exchange of data between the server |
| existed well before they were implemented to | | | | and the client. It is an API (application program |
| increase web page usability. This article will describe | | | | interface) that uses Javascript to transfer text data |
| the development of the components that make up | | | | like XML using HTTP (hypertext transfer protocol) |
| Ajax and their uses. | | | | thereby establishing independent communication |
| AJAX Background | | | | between the server-side and client-side of a web |
| As aforementioned, the components that provide | | | | page. Microsoft developed it in 2000 as a part of |
| the framework for Ajax execution include the | | | | Outlook Web Access. Mozilla incorporated |
| following: 1) HXTML, that blends HTML and XML | | | | XMLHTTPRequest in 2002 and Apple incorporated it |
| functions, 2) Cascading Style Sheets (CSS) that | | | | into Safari 2.1 soon after. |
| present markup languages intelligibly and style web | | | | AJAX Usage |
| content, 3) client-sided description languages like | | | | The uses of these Ajax components work together |
| JavaScript, 4) XMLHTTPRequest objects. | | | | to allow for automatic, user-based alterations of web |
| HTML (Hypertext Markup Language) is the primary | | | | pages. As an application of HTML in XML, XHTML |
| markup language for web pages. Markup languages | | | | allows for automated web processing through the |
| represent text and extra information about the text | | | | use of the standard XML library. CSS is primarily used |
| that corresponds to structure and presentation. | | | | to stylize web pages and making them more easily |
| Originally conceived by the on-line publishing industry | | | | understandable to users. Javascript allows accessibility |
| to interact with manuscripts, markup languages | | | | to the DOM (Direct Object Model) to allow for |
| transitioned into the digital age through HTML. HTML | | | | dynamic information presentation and increased |
| describes the structure of certain web page text and | | | | interactivity. The DOM is a standard object model |
| further complements that description with interactive | | | | that renders HTML, XML and other related formats. |
| forms and objects that affect web browser | | | | XMLHTTPRequest is important in Ajax web |
| behavior. | | | | development techniques to increase web page |
| XML (Extensible Markup Language) is considered a | | | | responsiveness and interactivity. For example, it is |
| general-purpose markup language. XML is an open, | | | | currently used in Google's Gmail services and |
| standard language that facilitates data sharing across | | | | MapQuest among other highly interactive sites. |
| information systems, particularly those connected via | | | | Points of Interest |
| the Internet. The latest version of HXTML 1.1 | | | | The technologies outlined above work together to |
| became a W3C (World Wide Web Conference) | | | | comprise Ajax programming. The primary benefits of |
| recommendation and, therefore, an industry standard | | | | this suite of technologies allow users to access and |
| in 2001. | | | | create web applications more quickly with a level of |
| CSS (Cascading Style Sheets) display the | | | | responsiveness usually attributed to desktop |
| presentation of markup written document. This style | | | | applications. This increased responsiveness is coupled |
| sheet language, which is also standardized by W3C, | | | | with increased interactivity that doesn't make it |
| presents structured documents whose content is | | | | necessary for the web page to reload every time a |
| reusable in a variety of contexts. Content can be | | | | user makes a new request of the web application. |
| attached to different logics to create different | | | | AJAX Tutorials provides Web 2.0 Application |
| presentations of the same data. Style sheets have | | | | development help , AJAX Resources and free AJAX |
| existed since the 1970's and SGML (Standard | | | | training information. Take part in AJAX Forums to get |
| Generalized Markup Language). CSS Level 1 became | | | | daily help with real time AJAX issues and problems. |
| usable in 1996. By 1998, CSS Level 2 was W3C | | | | Visit Learn AJAX for getting started with AJAX. |