Dynamic Web File Format Transformations with Grace.pdfVIP

a r X i v : c s / 0 5 1 2 0 6 8 v 1 [ c s .D L ] 1 6 D e c 2 0 0 5 Dynamic Web File Format Transformations with Grace Daniel S. Swaney, Frank McCown, and Michael L. Nelson Old Dominion University Computer Science Department Norfolk, VA 23529 USA {dswaney,fmccown,mln}@ Abstract. Web accessible content stored in obscure, unpopular or ob- solete formats represents a significant problem for digital preservation. The file formats that encode web content represent the implicit and ex- plicit choices of web site maintainers at a particular point in time. Older file formats that have fallen out of favor are obviously a problem, but so are new file formats that have not yet been fully supported by browsers. Often browsers use plug-in software for displaying old and new formats, but plug-ins can be difficult to find, install and replicate across all envi- ronments that one may use. We introduce Grace, an http proxy server that transparently converts browser-incompatible and obsolete web con- tent into web content that a browser is able to display without the use of plug-ins. Grace is configurable on a per user basis and can be expanded to provide an array of conversion services. We illustrate how the Grace prototype transforms several image formats (XBM, PNG with various alpha channels, and JPEG 2000) so they are viewable in Internet Ex- plorer. 1 Introduction Data formats for Web-accessible digital content are continually changing. Digital contents that are stored in older or unpopular formats are increasingly in danger of becoming inaccessible to modern web browsers. For example, the XBM im- age format was properly displayed by Microsoft Internet Explorer (IE) version 4, but IE version 6 is unable to display this format. Older formats like early pkzip, PostScript, and PICT images are no longer accessible or viewable with- out locating and installing old or special software. Newer digital formats are also likely to be inaccessible through a web browser until wide-spr