Indi- rection means sending mail, waiting for a reply, discovering that you forgot something or want to make yet another change and then going through the whole process again. There are also delays in updates taking noticeable effect due to the manner in which they are propagated. An additional shortcoming of traditional group usage is that the underlying operating system imposes a limit on the number of groups simultaneously associated with a user. In addition, a user has effective access to an essen- tially unlimited number of group memberships. An unprivileged user owning a group can add or remove members from that group.
Users also own their individual group memberships.
The authorization hierarchy is given in Table 1. The database contents are periodically con- verted to the flat files usually associated with Unix group information. However, these files are used as the equivalent of a local cache. In the absence of cached information related to group membership, the database is consulted directly. Thus updates to group ownership and membership are effectively instan- taneous.