[Zope] Zsyncer

[Paul Winkler]

On Thu, Jun 26, 2003 at 03:22:21PM +0200, Mireia.MUNOZ-DE-JESUS@ifaedi.insa-lyon.fr wrote:
> How does it works? I am having some little problems with this product. Can
> you help me?
> 
> I have two machines, machine1 and machine2. Synchronise from machine1 to
> machine2, i have no problem but doing the opposite is imposible. I have no
> errors, but nothing is modified.

doing the opposite IS possible - if machine2 can make an http 
connection to machine1's IP address / zope port.

check the configuration of your ZSyncer instance on machine2.
In the "destination servers" box, you need to have
http://foo:8080/my_zsyncer_instance

... where foo is the name or address of machine1.

How zsyncer works: when zsyncer is installed on both zopes, 
and configured correctly, the source zsyncer makes xml-rpc calls to
the destination zsyncer which allow it to compare the modification time
of an object. When you sync, for each item you have selected, zsyncer
uses the import / export machinery to create an in-memory export
of your object, transfer it to the remote system, and use xml-rpc to
import it.

It has some shortcomings:

- doesn't handle large amounts of data well - anything over 100 MB
isn't really practical.

- in order to get accurate comparisons, the two systems need to have
the system clock set very close. If the destination machine is too far
ahead, you could get "OK" for things that are not; if it's too far behind,
you will get "out of date" for things that are not.  

- if content is edited on both systems, it is quite possible that 
zsyncer could think the destination object is "OK" when in fact it's been
changed, which means you either need to back-sync or you have a conflict that
needs to be resolved.

I am doing some work on zsyncer, trying to improve it, but these are
difficult problems to solve.

-- 

Paul Winkler
http://www.slinkp.com
Look! Up in the sky! It's THE PROGRAMMER!
(random hero from isometric.spaceninja.com)