3.3 The features of SVG

The initial reasons for creating SVG may seem quite modest, but its XML heritage has resulted in a tool that is powerful and full of possibilities. As such, it is important to remember that some of its most compelling features, such as platform independence and interoperability with other XML technologies, are not exclusive to SVG, they are just part of membership in the XML family. Because SVG is freely available, nobody 'owns' it and no single software company can tailor it to their particular market. Like HTML, SVG is made up of nothing more than text, which can be viewed by developers and users alike, which makes it easy to see and share the way SVG documents are structured. For HTML, this resulted in hugely accelerated development, and this will probably be the case for SVG.

One of the primary complaints about Flash is that documents are created in the proprietary .swf file format, which is binary and therefore not meant to be read or accessed by people (Laaker 2002, 13). Users and developers can view SVG, and the contents are understandable to humans and not just computers (Jackson 2002). SVG allows selective display of elements in an image. Because vector graphics can be created in layers that can be turned on and off, those layers can be preserved in SVG, and interacted with using a scripting language like JavaScript (or more accurately, ECMAScript) (Watt et al. 2003, 17). The text that makes up an SVG graphic is also available to search engines able to read XML, so if a vector graphic contains text it is still recognisable as such even if it is embedded into an image (Watt 2002, 95).

This ability to recognise the textual parts of an SVG image also allows for internationalisation of its content. If the settings in a browser are set for a particular language, the SVG image will display the same graphical elements, but the textual elements that are appropriate for that language will be chosen and displayed (Watt et al. 2003, 19). Browser detection and SVG will also allow for greater flexibility in the future for designing accessible websites. SVG's resolution independence already means users with visual limitations can scale images to a level of magnification that is comfortable. For users that require images with different colour contrasts or text only, SVG should be able to serve a version of the same page to meet their needs. Rather than designing Websites for an accessible lowest common denominator, developers could create one site that can be viewed (or not, in the case of audio browsers) in a variety of ways. This will be somewhat in the future, however, since accessible SVG browsers and plug-ins will have to be created first (Watt et al. 2003, 510). SVG can also create graphics that are data-driven and generated dynamically from a server. This can be done in a variety of ways using existing programming languages like PHP (PHP: Hypertext Preprocessor), Practical Extraction and Report Language (PERL), Active Server Pages (ASP) or Java Server Pages (JSP), but the result is a visualisation that can be created 'on the fly' based on user criteria (Watt et al. 2003, 695-98).

While XML is a rapidly growing specification, it is not natively supported by all web browsers, but this is changing. The most popular browsers that do offer such support are Mozilla's Firefox 1.5. (Anon. 2006c), and Opera 8 (Anon 2006d). These are both available for a wide variety of operating systems, including the most popular: Windows, Macintosh and Linux. Testing of these two browsers using Windows XP and Apple OSX revealed quite uneven implementation using Firefox, while Opera was much more solid. Because SVG is non-proprietary there are several companies and organisations with an interest in furthering its development, and they have added SVG support to their products or created plug-ins for other browsers. Adobe's SVG Viewer plug-in is the most widely used, with the broadest distribution and compatibility with all major browsers or platforms.

This short introduction can only touch on the power and versatility of SVG and XML. It is important to note, however, that although designed for the Web, XML has also been quickly adopted for other uses. As a non-proprietary way to handle data-intensive tasks, XML can be shared across platforms and programs, and has been taken up enthusiastically by developers working in areas that may have nothing to do with the Web. This will almost certainly be the case for SVG as well. SVG is not just part of XML, it is XML, and as such cannot be compared to other technologies without considering the weight of XML behind it.

Install the SVG viewer.


© Internet Archaeology URL:
Last updated: Tue Jul 18 2006