ONC+ Developer's Guide

Port Monitor Messages

The format of messages from a port monitor to the sac is defined by the structure pmmsg:

struct pmmsg {
 	char pm_type;                /* type of message */
 	unchar pm_state;             /* current state of port monitor */
 	char pm_maxclass;            /* maximum message class this port
                                   monitor understands */
 	char pm_tag[PMTAGSIZE + 1];  /* port monitor's tag */
 	int pm_size;                 /* size of optional data portion */
};

Port monitors may send two types of messages to the sac. The type of message is indicated by setting the pm_type field of the pmmsg structure to one of the following:

PM_STATUS state information PM_UNKNOWN negative acknowledgment

For both types of messages, the pm_tag field is set to the port monitor's tag and the pm_state field is set to the port monitor's current state. Valid states are:

PM_STARTING starting PM_ENABLED enabled PM_DISABLED disabled PM_STOPPING stopping

The current state reflects any changes caused by the last message from the sac.

The status message is the normal return message. The negative acknowledgment should be sent only when the message received is not understood.

pm_size indicates the size of the optional data part of the message. pm_maxclass is used to specify a message class. Both are discussed under "Message Classes". In Solaris, always set pm_maxclass to 1 and sc_size to 0.

Port monitors may never initiate messages; they may only respond to messages that they receive.