I just looked at Apache::Session::BerkeleyDB and some other modules. It seems like all of them tie a hash to a disk file. I guess what I'm trying to do is something slightly different. I want to store multiple sessions in a single file... and then I want to be able to create a session object that a client would use that would only use data from a single session (single anynymous hash, referenced by session id). If you look at the code I provide you'll see what I'm trying to do.

My problem is that I don't know how make the top level of hash notice that something had changed on the lower level, so that it updates the file on the disk. I'm looking for ideas at this point.

But in any case, thank you for the hints to the modules that do similar work I might use them for some of the future projects.