RE: [cgmo-webcgm] Z compression research

[Lofton Henderson <lofton@rockynet.com>]

At 06:56 AM 9/20/2007 -0700, Cruikshank, David W wrote:
>I guess I also raises the question of if you find the "magic number" for 
>zcompress how do you know it's not an svgz file instead of a cgmz file?

Decompress it?

While "file sniffing" is a common practice (to determine GZIP, or SVG vs. 
CGM, or CGM encoding), it is not actually the recommended way of tracking 
content type -- not supported by any standards or protocols.

-Lofton.

>-----Original Message-----
>From: DULUC, Franck [mailto:franck.duluc@airbus.com]
>Sent: Thursday, September 20, 2007 6:31 AM
>To: Don Larson; CGM Open WebCGM TC
>Subject: RE: [cgmo-webcgm] Z compression research
>
>i think it is the same for VRML.
>
>Franck
>
>-----Message d'origine-----
>De : Don Larson [mailto:dlarson@cgmlarson.com] Envoyé : mercredi 19 
>septembre 2007 23:07 À : CGM Open WebCGM TC Objet : [cgmo-webcgm] Z 
>compression research
>
>
>All,
>
>After researching Z compression, I have determined that the file format 
>used for compressed SVG is the same used by "gzip" an open source 
>software. And that there indeed is a magic number in first 2 bytes 
>indicating Z compression.
>
>The complete specification for the gzip file format can found here:
>http://www.ietf.org/rfc/rfc1952.txt
>
>Further details on gzip and source code can be found at:
>http://www.gzip.org/
>
>
>Regards,
>Don Larson
>
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