We have a large financial application that consists of a central .EXE that then calls the application .EXE's (i.e. AR.EXE, AP.EXE, PS.EXE). We want to convert it to ntier and are wondering how deep to go with the breakout. Should we set up separate DLL's for the application Presentation, Business, and Data layers for each application (i.e. AR_PresentationTier.DLL, AR_BusinessTier.DLL, AR_DataTier.DLL) and call each DLL through creatobjects or set up the same funtionality within a single DLL (or EXE). What sort of penalty is paid by using DLL's for things like customer setup and maintenance and debugging (or lack thereof).

We have been studying this issue for a while and have looked at COMCodebook (overkill in my opinion) and Jim Booth's excellent OOP starter. There doesn't seem to be any standard in nTier systems within the Fox community that I am aware of.

This is a major rewrite and we want to make sure we travel down the right path.

Thanks in advance.