Layered Athena was designed to allow private workstation owners to choose which parts of the Athena systems packs they would like to install. To achieve this, it was necessary to come up with a division of the system pack into subsets that were meaningful to users, and to determine what subsets depended on what other subsets. Figure 1 illustrates this division.
Figure 1: Subsets of the srvd with dependencies
This subset installs or modifies the necessary configuration files for support of Kerberos v4 clients. It installs basic clients, kinit, klist, kpasswd, rkinit, ksu, and the utility programs ksrvtgt and ksrvutil. It does not require modifying system startup files. The Kerberos subset could easily be extended to include Kerberized applications such as telnet and rlogin, providing an easy-to-use solution for private workstation owners who want to protect their passwords, but don't want any other Athena software.
This subset installs configuration files and the AFS cache directory, and modifies system startup files so that AFS is started on reboot. It also installs the utilities aklog, unlog, fs, pts, and vos. If a private workstation owner wants to get at files in AFS (which includes virtually all Athena lockers), the Kerberos and AFS subsets are enough.
Many Athena services are so simple and unintrusive that they can be packaged together in one subset, even though there's a wide variety of functionality. These services include hesiod, zephyr, moira, online consulting, global message of the day, kpop email, authenticated printing, and attach.
To ease use of these services when the login subset is not loaded, a script called login_athena is included which will allows the user to get tickets, Athena home directory, zephyr, and any other necessary setup.
The Athena X subset includes the standard X11 clients as we compile them. For newer Unix platforms, this subset is unnecessary, as vendors have largely caught up with Athena in terms of X releases.
This subset runs the Athena login program on the workstation. This means that anyone with an active Athena account can login to the workstation unless access is specifically restricted. This subset includes a lot of interaction with the base operating system, and is typically the most difficult part of compiling system packs for a new platform.
This subset includes emacs and its libraries and utilities. Many private workstation owners would like an easy way to install emacs without having to compile it themselves, even if they don't want any other Athena functionality.
This subset includes the man pages for all Athena programs and on some platforms, a modified man program as well. In the future, man pages may be bundled with the other subsets rather than be separate.
This subset provides the TeX and LaTeX formatters and associated utilities. Like emacs, it is a third-party package some private workstation owners may want, even if they don't want any other Athena functionality.
The subset provides ez and other applications built on the Andrew Tool Kit.
This subset contains Athena applications that don't fit into the ``Basic Athena Services'' or other subsets. They are small, easily-ported programs, so that it's convenient to lump them together into one subset despite the wide range of functionality provided. Applications include: olh, delete, mh, rcs, tcsh, eos, imake, notes, kerberized remote access, discuss, dash, perl, and much more.
This subset contains the libraries, include files, and other tools necessary to write programs that use the Athena basic services.
This subset was never implemented. It would handle automatic updates to new releases, etc. It was hoped that one day Layered Athena would reduce the effort needed to create an install kit for public workstations, however, the current Layered Athena paradigm cannot satisfy the requirements for that installation process, because it does not reinstall the base operating system.