[Owncloud] Syncing and Time Synchronization

[Klaas Freitag]

Hi,

as you know our current syncing requires that both machines (client and 
ownCloud server) operate on exactly the same time because we use the 
file modification time to decide which file to sync where.

Unfortunately for a couple of reasons we can not keep up the requirement 
of synced times any more, even if it might make sense.

I investigated the last couple of days what we can do. If times between 
server and client just had a constant difference, it were doable, but 
thats not the case. Time difference is variable in real world and that 
means we can't use the mtime to decide any more.

So the conclusion is that we use file content checksum to detect 
differences between the file representations on server and client, 
similar to what was said on this ML in the past and what other projects do.

For that, the best would be if the ownCloud WebDAV server would provide 
another WebDAV property that returns the md5-sum of the file or file 
list. That probably means that the md5 sum needs to be calculated on 
every file change on the server and be stored in the fs cache.

Is that doable? Who can help with that?

Best,

Klaas