[Zope] Re: Zeo as a Zeo Client

[David Pratt]

Andreas Jung wrote:
> 
> repozo does not help you syncing multiple ZEO server..it just performs
> an incremental backup of an existing Data.fs file. And I don't know of 
> any solution have multiple "master" ZEO servers. There can be only one.
> 
> -aj

For sure. I guess the best one could have would be replicated storage 
clients that when offline could operate on their own data. When they go 
online they would first attempt resolve their data with the (master) 
server (synchronizing), and then append each new transaction to the 
local replica as it was occuring (replicating) so that before you went 
offline again, your storage is up to date.

I think this is all possible with a sync server, each client having an 
independent asynchronous loop for synchronizing, and a synchronization 
protocol for two way syncing. Zope has most of this now but it was never 
designed to provide data to the local storage to keep it up to date 
(while the zeo client is being used). This would be quite handy and I 
think there are some possibilities to do this.

I guess in a general way, this is what the spread is doing for ZRS but 
the mechanism and use case is different. I don't think you'd want any 
client to be offline for long with this service with a replicated 
storage client. I think the idea is more of a hot backup in case of 
failure of the main storage but I know little of ZRS.

Regards
David