Today we had a scenario where there was a lot of confusion as to where code is running in the Role Tailored Client.
Is the code running on the service tier, or in the Role tailored client ?
This had mainly to do with file access, and finding whether the server file or the client file should be used.
2 points worth noting (from MSDN):
1. You specify whether Automation objects run on the RoleTailored client or Microsoft Dynamics NAV Server by using the CREATE Function (Automation) in C/AL code of the object that runs the Automation object.
2. Not all Automation variables can run on both client types.
This is going to become a lot more important in the future,
Please be sure to read and understand the following MSDN article as it will save a lot of headaches.