Distributed Objects for Database application

We are currently evaluating development tools for building a 3-tier
database appplication. Ideally, we'd like to build the 1st tier using a
tool such as Delphi 2.0 C/S, VisualAge, or Visual C++. The middle tier
objects (which define the business logic, database sources) need to be
cross-platform deployable. The third tier is a RDBMS server tier (mostly
for UNIX).

The problem we're facing is with the middle tier obviously. I know that if
use Network OLE we could interface with distributed objects on other
"Microsoft OS" platforms. However, we need these objects to reside on UNIX
boxes in a large network environment. Are there any middleware tools out
there that would allow us to develope the middle tier objects for UNIX and
then interface them with the client?

Are there any OLE to CORBA middleware tools. If so how much do they cost.
Are there any runtime licensing fees attached? OLE/DCOM is virtually free.

Has anybody else successfully done this? What problems did you encounter?
Development costs? Learning curves?

Please e-mail your reply to ar...@medcmp.com

Any help is greatly appreciated.

Thanks
Arif