Shared Cross-Process Data Object

I need an object/class that keeps data synchronous over multiple processes. Like a singleton instance that works across processes. Is there already a built-in class that can handle this or what's the best way to implement such开发者_开发百科 a thing (NSConnection, NSDistributedNotificationCenter, etc... ?)

Regards, Erik

Update:

Currently I have implemented such a thing using NSUserDefaults domains and syncing them to disc. But actually I prefer to avoid file system access, because it stresses the disc.

The filesystem will do that for you, or a database. Or you could even serve the shared data via Distributed Objects from a single server process.