pdf: 600KB - Potsdam Institute for Climate Impact Research

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Example 3: Generating graphical views of model structure, viewable in a web browser
Simile, and similar software, have shown clearly the value of diagrammatic representations of
model structure for building and communicating models. However, to date such tools operate as
stand-alone software products on one's own PC. New modelling will involve people searching
for models or submodels across the web, and it's important that we develop the most useful ways
of informing these people about the various models they encounter. Along with prose
descriptions, HTML and other text-based presentations, it is desirable to use visual methods as
well.
As it happens, until recently there have been no single standard for displaying vector graphics
(lines, rectangles, circles etc) in web browsers. (There were a number of approaches under
development, such as PGML - Precision Graphics Markup Language - and VML - vector Markup
Language - but none of these satisfied all the requirements of a vector-graphics language for web
browsers.) Consequently the W3C (the World Wide Web Consortium) set up a working
committee to come up with a standard language, and the result is SVG (Scalable Vector Graphics)
[See URLs]. Being XML-based, it can be incorporated into XML documents, and is a sophisticated
graphics language in its own right, with the ability to support (e.g.) user interaction and animation.
I have developed an XSLT program to illustrate the ability to display any Simile model diagram in
SVG, and thus to enable it to be viewed in a web browser. Please note that this is a very early
prototype.
This file can be viewed in any web browser (Netscape, Internet Explorer) that has a SVG plug-in
(obtainable from http://www.adobe.com/svg), as shown in Fig. 8.5. In the near future, browsers
will have an SVG capability as standard.
Fig. 8.5 A Simile model, shown in Simile itself (left), and rendered in a web browser (Internet
Explorer) (right)