Accessing indd files in a three-tier setup

I made a prototype InDesign Server application where the client tier, middle tier (containing the .indd files) and InDesign Server tier were all the same (my Mac).
I'm currently setting up an environment where each tier is a separate machine on the local network. There is only 1 InDesign Server tier, but there are multiple client and middle tiers.
The middle tiers (where the .indd files reside) can connect to the InDesign Server tier (via Corba).

My question is whether there is a common way the InDesign Server tier can access the .indd files on the middle tiers?

The most obvious solution seems to be via shared folders, but I was wondering if there is another, more flexible solution.

Thanks in advance.

Chris.