On Feb 13, 2008, at 6:24 PM, devzero2000 wrote:

> I have't well understood the RPM5 xar claim and it'use in rpm.
>
> Can someome offer some help ?
>

Sure.

XAR is a archive format that has metadata in XML, and
per-file compression.

You can find details at
     http://code.google.com/p/xar/

XAR is the "package" format used in Apple Leopard. I add
scare quites because there are important differences between
packages <-> archives, the main difference is that packages
have richer metadata, and are used for more than bundling
up a bunch of files.

What rpm-5.0 has atm for XAR support is a conversion program
from RPM <-> XAR.

An rpm consists of 4 sections: Lead, Signature, Header, Payload.

The conversion program splits the 4 concatenated sections into 4 files
in a XAR archive called (unsurprisingly)
     Lead
     Signature
     Header
     Payload

rpm-5.0 will query either a XAR or and RPM package.

What isn't done yet (for many reasons, including that XAR is just
stabilizing, and also that much better could/should be done with XAR
format than splitting the existing RPM format into 4 pieces in a XAR
wrapper) is permitting install's of XAR packages.

The converter program is in tools/txar.c.

Feed it a *.rpm on the CLI and it will produce a *.xar package in the  
same directory.
Or vice versa to convert XAR -> RPM.

So XAR atm is still rather uninteresting even if nominally present in  
rpm-5.0. Full
"production" deployment will take much more than an implementation in  
rpm.

73 de Jeff