Re: [Opensync-users] OpenSync 0.15 released

[Helge H. <hel...@op...>]

On Mar 31, 2005, at 17:17, Armin Bauer wrote:
> ah i see. would it be possible to issue a query like "give me all 
> events that have been changes since the last sync"

No, this is SyncML ;-)

> or will this information have to be maintained locally (which would be 
> bad since we would need to transfer all items to calculate the hash)?

The synchronisation is based on HTTP etags. To calculate the set 
difference (added/delete/changed URLs) you need to retrieve the etag, 
not the actual content.
This is one of the PROPFIND queries you need to implement, its in 
section 5.1 of the draft-01:
   http://www.groupdav.org/draft-hess-groupdav-01.html

Yes, this only works well up to a certain size of a folder (depending 
on the speed of the connection). Fortunately WebDAV results compress 
very well (deflate content-transfer-encoding), so the response size is 
reasonable and the operation itself is fast on most/all servers.
It will work well for some 10.000 objects per collection, but certainly 
breaks if it contains 100.000. So its fine for about 28 years of 
calendaring data, which is OK for us ;-)

Another disadvantage is that the first sync between client and server 
will be rather slow (will issue a separate HTTP GET request per 
object). But since this is a once-per-client operation, we considered 
this reasonable too.

Greets,
   Helge
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