SQL Server Compact Windows Mobile Synchronization Services Sync Services Oracle ADO.NET

Question

Hi,

I wanna synchronize in a bidirectional manner SQL Server Compact (running on Windows Mobile) and an Oracle server database. I wanna use Microsoft's Sync Services for ADO.NET and C#.

Handheld <---> Middletier/Desktop-PC <---> Oracle DB

Did anyone ever tried implementing this scenario? In the documentation of Sync Services I read that my wanted scenario should be possible. But unfortuanately I couldn't find any example. Additionally I didn't understand which classes of Sync Services I have to use in my Handheld application and which ones in my desktop application. I also don't know how to implement a transport mechanism (proxy, service) to communicate from PDA with desktop. I've read I have to implement a WCF service. Is that true? How does this work. Listens this service all the time at my desktop for the case a handheld is connecting?

I would you thank you for any basics, hints, links or examples

Bye
Aness

PS.: I've successfully implemented bidirektional synchroniation if SQL Server Compact is running on a desktop pc. But I do not need a separate transport layer for this.