Re: [Duplicity-talk] Re: [rdiff-backup-users] Tar replacement - format proposal

[Will Dyson]

On Fri, 2003-09-26 at 09:16, John Goerzen wrote:

Originally sent this just to John, but intended it for the whole list.

> Moreover, you don't need XML for what you are trying to achieve.  All you
> need is something "more versatile than tar".  It shouldn't be hard to arrive
> at a key/value system.  For instance, for files, you could have:
> 
>   NAME\0/foo/bar/baz\0
>   MTIME\0514341312\0
>   CTIME\03413413214\0
> 
> Of course, you could write the MTIME and CTIME in binary, and you could
> abbreviate those names to "N", "M", and "C" to save time.  What's more, this
> format is quite extensible, almost to the same degree as XML, and you save
> space in the archive and space in memory and library requirements, not to
> mention ease processing.
> 
> Null-terminated strings are easy for anyone to parse without having to load
> a separate library.  (You could also use Pascal-style "leading length byte"
> strings, which are also easy to parse.)

If we decide to echew XML, I would go with something like the record-jar
format described in The Art of Unix Programming
(http://www.catb.org/~esr/writings/taoup/html/ch05s02.html). 

However, XML has the desirable property of being hierarchical. This is
nice when describing things like ACLs. Hierarchical structures can be
flattened into something like this

Name: /foo/bar/baz
...
AclEntry-read-permit-1: username
AclEntry-read-permit-2: otheruser
AclEntry-read-deny-1: someuser
...
%%

But I think it is worth considering the hassle of this vs the hassle of
creating a stripped down or special purpose xml parser.

-- 
Will Dyson
"Back off man, I'm a scientist!" -Dr. Peter Venkman