The Service Access Facility

The Service Access Controller

The Service Access Controller (SAC) is the administrative point of control for all port monitors (and therefore for all ports on the system). Its job is to maintain the port monitors in the state specified by you. It accomplishes this through these actions:

During initialization, the SAC daemon customizes its own environment by invoking the per-system configuration script supplied with the SAF.
Next, the SAC daemon reads its administrative file to determine which port monitors are to be started. For each port monitor specified, the SAC interprets the corresponding configuration script (if one exists) and then starts the port monitor itself.
Once the SAC daemon is running, it polls the port monitors periodically and initiates recovery procedures if necessary.

Because the SAC daemon is started by the init(1M) command during system initialization (through an entry in /etc/inittab), it starts working as soon as you enter multi-user state. ``How the SAC daemon and port monitors are generated'' shows how the init process spawns the SAC daemon (sac), and in turn, how the SAC daemon spawns port monitors such as ttymon, listen and inetd.

How the SAC daemon and port monitors are generated

From time to time you will want to query the SAC; for example, to check the status of the port monitors. You may also need to make changes to the port monitors. For example, you may want to enable a disabled port monitor or start a port monitor that has been killed. sacadm(1M) and pmadm(1M) allow you to issue commands to the SAC which, in turn, communicates with the port monitors.