Actually Java NIO locks the file at the OS level, if the OS provides that feature. Windows does. I played with the idea a bit at IUPUI during a distributed syst

Actually Java NIO locks the file at the OS level, if the OS provides that feature. Windows does. I played with the idea a bit at IUPUI during a distributed systems class. You're correct that having to do the locking in userspace would be difficult. Some one could crack it. That doesn't mean much legally. Look at DRM: it's crackable. The industry still uses it.