Writing Monitors for the Event Monitoring Service (December 1999)

Chapter 3 65

Creating a Resource Monitor

Writing the Monitor

When you write the resource monitor, do not have it read from ﬁle

descriptor 0 (normally STDIN); it will be done automatically by the

rm_get_next_event() function.

Environment Considerations

A resource monitor’s environment is inherited from the Registrar, which

is inherited from inetd(1M).

Resource monitors should not expect user-type environment variables to

be present. In particular, HOME, DISPLAY, LANG, and NLSPATH will not be

set.

Terminal Considerations

There is no terminal associated with the resource monitor process, so it

is not possible to display information to the screen. Use the EMS logging

facilities to output information. See the chapter, “The EMS Application

Programming Interface (API)” for more information about EMS logging.

Monitor Info Object Considerations

When a resource monitor calls rm_monitor_start(), a Monitor Info

object of type RM_MONITOR_INFO_OBJECT is created, and the global

rm_monitor_info variable is set to point to that object. The

rm_monitor_info variable is of type rm_object_addr. Several ﬁelds of

the Monitor Info object are set automatically by the EMS API when the

object is created, and several ﬁelds must be set by the resource monitor.

The Monitor Info object ﬁelds are listed in Table 3-2:

Table 3-2 Monitor Info Object Fields

Field Name Type Description

RmMonitorCommand char * A pointer to a single

null-terminated string that is the

command line that was used to

invoke the monitor.

This ﬁeld is set by EMS and

should not be modiﬁed.