2.2.1 Basic Functionality of the in.named Method Implementations

Consider the basic functionality of the HA-in.named method implementations. The start method is not registered in this case, and all the work is accomplished in the start_net method. Similarly, the stop method is not registered for HA-in.named, and all the work is accomplished in the stop_net method. The start_net method starts up the in.named daemon, and the stop_net method kills the in.named daemon by sending a -TERM signal.

The Sun Cluster API requires each method to be idempotent--that is, repeated calls on a method must have the same effect as a single call on that method. For HA-in.named, the idempotency is achieved by having each method test whether its work has already been accomplished. That is, start_net tests whether the in.named daemon is already running, and stop_net tests whether the in.named daemon is already stopped.

The Sun Cluster process monitor facility consists of two components, the pmfadm(1M) command and the rpc.pmfd(1M) process monitor daemon. In the sample application, the pmfadm(1M) command is used to start and kill the in.named daemon, and to query whether the in.named daemon is already running. See the pmfadm(1M) and rpc.pmfd(1M) man pages for details.

The HA-in.named method implementations use the haget(1M) utility program to extract information about the Sun Cluster configuration. (See the haget(1M) man page for details.) The method implementations log their error messages to syslog(3), because the code runs without user attendance. They use the same syslog facility that Sun Cluster uses. Determine the syslog facility name by calling haget(1M) with the option -f syslog_facility.