Backing up RDF files and writing gzip files

Applications that use local RDF files to store data have a significant 
potential point of failure.  I have come a cropper on a few occasions 
with RDF files getting 'corrupted' and trying to repair them by hand is 
well nigh impossible.

For my own XUL/RDF applications it struck me that a rolling 'backup' 
would be a neat idea - when an RDF file was successfully opened/parsed a 
zipped backup would be created.  The backups could be rotated and a user 
could also undertake a manual backup of the critical data when every 
he/she wanted.  Since these files can be quite large compressing would 
be essential.

The problem I discover is that XPCOM has an interface for reading zip 
files (an essential part of supporting http/1.1) but I cannot find a 
means of writing zip files.

The combination of XUL/RDF/XPCOM/Javascript is immensly powerful for 
developing cross platform applications but it seems to suffer somewhat 
from being too browser centric.

To be really useful, as a development platform, xpcom's nsIZipReader 
should have a nsIZipWriter counterpart.  Clearly, adding this type of 
component, as part of the standard browser release, would increase the 
footprint and would not be desirable but it *should*, IMHO, be a 
standard xpcom component, available to application developers to 
incorporate into their application.

The ultimate question is, therefore, are there developers working on 
standard (open-source) xpcom components that make the XPCOM platform 
more comprehensive?  If I was to write an implementation of 
"nsIZipWriter",  would there be demand and testing/development support 
out there?

XUL/RDF/XPCOM/Javascript could liberate developers from the clutches of 
MS-COM and fulfill the cross-platform potential only dreamt of for 
client side JAVA. To do this it needs to be more comprehensive than a 
browser application.

Reactions?

Geraint