CM> I am writing a DLL that will manage access to a central database on disk.

 CM> The problem I hae encountered is, what if instances of 
 CM> this program are running on another machine on a 
 CM> network.  Clearly, every machine will need access to


A dll is not required to do this (but can be used if you want).

There are two ways that I can think of to do what you want:

    1) File locking.  (See DosSetFileLocks()).   This is more
       traditional, and is what many DOS products use (Btrieve, Foxpro,
       Paradox, etc).  A system with more than a few users will have
       lots of contention at the network server though.

    2) Client/Server with Named Pipes.  This is a lot more cool,  and
       easier IMO.  Write a server process that services requests via a
       named pipe.  It will work with local clients with plain OS/2.
       With a LanServer/LanManager/Netware,  it will work with remote
       clients too.


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