Specify the address of a procedure to call when a PMDF RESTART or PMDF SHUTDOWN command has been issued.

PASCAL

status = PMDF_set_call_back

(proc, facility, facility_len)

argument information

Argument	Data type	Access	Mechanism
proc	procedure	read	reference
facility	descriptor	read	reference
facility_len	signed longword	read	value

C

status = PMDFsetCallBack

(proc, facility, facility_len)

argument information

int PMDFsetCallBack(void (*proc)(), char *facility, int facility_len)

Arguments

proc

An asynchronous procedure which will be called at AST level whenever a PMDF RESTART or SHUTDOWN command is issued. This procedure will be passed by reference a single integer parameter explaining the reason for the call back.

facility

Facility or component name to associate with the routine using this call back. When a RESTART or SHUTDOWN command specifying this facility name is issued, then the call back procedure will be invoked. The length of this string should not exceed 17 bytes.

facility_len

Length in bytes of facility.

Description

PMDFsetCallBack is only functional on OpenVMS systems. On other systems, it merely returns PMDF__OK and does nothing.) Through a call back procedure, programs can be notified whenever a PMDF RESTART or PMDF SHUTDOWN command has been issued. Unless PMDFcancelCallBack is called, the call back procedure will be called each and every time any of the five commands are issued

$ PMDF CACHE/CLOSE $ PMDF RESTART $ PMDF RESTART facility $ PMDF SHUTDOWN $ PMDF SHUTDOWN facility

where facility is the facility name. The call back procedure will be invoked at AST level and passed, by reference, a single argument. This argument is of type integer and has one of three values:

Symbolic name	Value	Command issued
PMDF_CACHE_CALLBACK	8	PMDF CACHE/CLOSE
PMDF_RESTART_CALLBACK	16	PMDF RESTART [facility]
PMDF_SHUTDOWN_CALLBACK	24	PMDF SHUTDOWN [facility]

In response to a PMDF_CACHE_CALLBACK call back, the program using the call back should close the queue cache as soon as is convenient by calling PMDFcloseQueueCache . In response to either of the other two call backs, the program should exit in an orderly fashion as soon as is convenient. In the case of PMDF_RESTART_CALLBACK, the program should be restarted (i.e., re-run). On OpenVMS systems, this routine will enqueue five resource locks each with blocking ASTs. In order to accomplish this, SYSLCK privilege as well as a sufficient enqueue and AST quotas are required. The call back procedure will be invoked at AST level. Note that the delivery of the blocking AST's used by PMDFsetCallBacks can be hindered in a program which itself spends most of its time at AST level.

Return Values

PMDF__OK	Normal, successful completion.
PMDF__INVSTRDES	Invalid string descriptor for facility: descriptor has an invalid value in its DSC$B_CLASS field. No call back established.
PMDF__STRTRUERR	Length of facility exceeds 17 bytes. No call back established.
On OpenVMS systems	Any error returned by the $ENQ System Service.