Enterprise beans aren't allowed to access files primarily because
files are not transactional resources. Allowing EJBs to access files
or directories in the filesystem, or to use file descriptors, would
compromise component distributability, and would be a security
An EJB may be distributed across a number of backend machines and may be moved between machines at the container's discretion. To enable this distribution model, EJB must follow a strict specification-defined ruleset for what they can and cannot do.