Last week on the Six Colors podcast, Dan Moren mentioned a very specific Apple support document that I was able to find via the Wayback Machine:
As if it were a swarm of bees, you should stay away from the SyncServices folder in Mac OS X. Removing or modifying anything in it—or in subfolders within it—may cause unexpected issues. This folder is located in your Application Support folder, in your Library folder, in your Home folder.
Deleting or modifying things in the SyncServices folder may cause unexpected results such as:
- Duplicate contacts in Address Book or appointments in iCal.
- Data loss in Address Book or iCal.
Important: Any lost or duplicate data could propagate to other devices and computers via iSync and .Mac sync. This means data could be lost on other computers.
Amazingly, Apple still has documentation published about this subsystem of OS X, which sometimes had a space in its name and sometimes didn’t.
John Siracusa wrote about it in his OS X Tiger review:
Sync Services is a new framework for synchronizing data between applications, devices, and entire machines. Think of it as the publication of the functionality behind iSync to all third-party developers. The iSync application is now just an interface to the public Sync Services engine. In fact, it actually passes off all machine-to-machine syncing to a tab in the newly enhanced .Mac preference pane.
I expect a lot of third party developers to add sync support to their applications. Apple has already expanded the reach of Sync Services among its own applications, adding support for syncing Keychains and Mail accounts, rules, signatures, and mailboxes.
The interface for developers is very nice. They don’t have to worry about many of the ugly details of data syncing: conflict management, change notifications, duplicate data detection, or .Mac connectivity.
That leads to the one sore point. Applications that use Sync Services automatically support .Mac syncing, but there’s apparently no facility for syncing with networked services other than .Mac. It would be nice if the network storage part of Sync Services was also expandable by third parties. But I guess this is yet another way to make the $99-per-year .Mac subscription service more attractive.