Re: Backward compatibility of next beta

[Frank Crawford]

On Sun, 2020-02-02 at 22:44 +0100, Arrigo Marchiori wrote:
> Hello Frank,
> 
> On Thu, Jan 30, 2020 at 10:57:09PM +1100, Frank Crawford wrote:
> 
> > On Thu, 2020-01-30 at 11:40 +0100, Arrigo Marchiori wrote:
> [...]
> > > Maybe you could find a solution by using the --remote-
> > > schema parameter? 
> [...]
> > No, the use of "--remote-schema" is the issue as it passes data between
> > the two programs in a specific format that has changed between python2
> > and python3 because of internal variations.
> 
> I may have not explained myself correctly, or I might not have
> understood anything at all. I'll try again :-)
> 
> For what I understood: the "--remote-schema" is the template for a
> command that is popen()-ed.
> 
> If your server _and client_ have two executables for rdiff-backup, say:
>  A) ~/rdiff-backup-old/rdiff-backup
>  B) ~/rdiff-backup-new/rdiff-backup
> 
> What is the problem in having the client calling:
> 
>  1) ~/rdiff-backup-old/rdiff-backup --remote-schema 'ssh -C %s 
> ~/rdiff-backup-old/rdiff-backup --server'
> 
> or:
> 
>  2) ~/rdiff-backup-new/rdiff-backup --remote-schema 'ssh -C %s 
> ~/rdiff-backup-new/rdiff-backup --server'
> 
> The old version on the client would call the old version on the
> server, and the new version on the client would call the new version
> on the server.
> 
> What ``Old'' and ``new'' are, can be chosen with total freedom: stable
> and beta? Python 2 and Python 3? Script and self-contained binary?
> They would be completely independent, because the only common part
> would be ssh transmitting their data.
> 
> This still requires to have the same versions of rdiff-backup on the
> client and servers, but does not require an upgrade, in terms of the
> new version _substituting_ the old. They could coexist side by side!
> 
> I hope I could explain myself more clearly now.

Ahh, yes, much clearer, and yes something along that line would work. 
It is just a scripting exercise of some form to get it working.

> Regards,

Regards
Frank