Has anyone succesfully configured CAP (columbia Appletalk Protocol) to work with an NFS mounted filer?

Yes. We have at least one other customer that I'm aware of doing this (NFS mounting a filer file system on a UNIX machine, and then running one of the freeware AppleShare/Talk servers on said UNIX machine to "re-export" that file system to Macintosh clients via the Apple protocols).

I am having problems that appear to revolve around NFS file locking. [...] In some circumstances, CAP AUFS using NFS mounted filesystems may complain about files being locked when they are not obviously so. This is usually the result of missing lock daemons or simply brain-dead or buggy NFS code.

And they don't define exactly *what* circumstances? Hmmm... :-)

Well, there's one thing I can think of that may be catching you/it unawares. If you have Windows/CIFS clients concurrently accessing the data that is being accessed by the Macs via NFS (indirectly), the semantic meaning of any CIFS file/record locks that are being established by your Windows clients are enforced on the NFS side in a mandatory way. The various Windows operating systems from Microsoft implement a mandatory locking scheme, and our SecureShare technology ensure that these mandatory controls are honored in the multiprotocol context. That's something to be aware of.

What it means in reality is that when/if CAP "probes" for the presence of locks via fcntl(), it may find locks that have originally come from the CIFS side. Also, if it tries to read and/or write data in a manner that would be in violation of a pre-existing CIFS mandatory lock, it will have those operations failed, even though the attempt is being made via NFS.

Keith