## 3 Creating 3D Web Applications with XML3D  
Web technologies are omnipresent; not only for distributing digital information in the Internet, but also for forming the base of a ubiquitous application platform. Thereby, the content itself rapidly evolved from basic text data without any styling, over dynamic and attractive web pages including styling and images, to sophisticated web applications with heterogeneous data sources and multimedia elements such as videos or live communication features. Motivated by the fact that we are living in a 3D world and that more and more communication media is shifting towards 3D visualization, web developers always aimed at creating 3D content. However, the main ideas in this area mainly comprise the integration of additional 3D content which only can be visualized when additional software, such as Java3D or VRML viewers, are installed. A platform-independent and portable solution has not yet been developed so far, but in the last two years--trying to push 3D to the future Internet--different initiatives and ideas for creating a quasi-3D-standard for the web has been conducted.  
One promising possibility for the creation of 3D web content is XML3D. It is an extension of HTML5 which allows for the creation of interactive 3D graphics. The specification of XML3D has been developed together by the German Research Center for Artificial Intelligence (DFKI), the Intel Visual Computing Institute (IVCI) and the Saarland University. These are furthermore the lead institutions driving the development of XML3D as well as the efforts for making XML3D an integral part of HTML5, thus the common standard for 3D web content.  
XML3D is aiming at a maximum compatibility with HTML5 as well as XHTML. For the generation of graphical objects, XML3D mainly features triangles which can then be utilized for describing nearly any arbitrary shape [31]. Following an declarative approach \"_XML3D fully leverages existing web technologies including HTML, Cascading Style Sheets (CSS), the Document Object Model (DOM), and AJAX for dynamic content_\" [15]. That is, all 3D elements are part of the DOM, thus common DOM scripting and events, such as deletion of objects or on-demand integration of additional content, are fully supported. In particular, XML3D aims at enabling programmers to create 3D content without actually having any specific knowledge about certain 3D technologies [31]. That is, basically every web designer who is familiar with common World Wide Web Consortium (W3C) standards such as (X)HTML, CSS, _etc._ is able to create and integrate 3D elements into a web application. This is also regarded as one of the main differences between XML3D and other approaches like WebGL, O3D or X3 DOM [31]. The possibilities and feasibility of XML3D have already been demonstrated by integrating XML3D support into WebKits and Mozilla browsers, as well as with a portable WebGL/JavaScript based version [15]. Most of the latest existing browsers such as Firefox or Chrome are already able to visualize XML3D content, thus applications which are based on this technology can already be utilized by the broad public. The Microsoft Internet Explorer does however not yet support any kind of 3D content. For more information on XML3D please refer to the publication [15] as well as the current specification version 0.4 [32].