High Availability Monitors Version A.03.02 Release Notes

Writing NOF Applications
Description of the NOF API Entry Points
Chapter 2 93
• For the following verbs, the application supplies a
null value:
— QUERY_NODE_ALL (to obtain a list of running
nodes)
— QUERY_CENTRAL_LOGGER
• For all other NOF verbs, the application supplies
the value that was returned on the
CONNECT_NODE or OPEN_FILE verb.
nofvcb Pointer to a Verb Control Block (VCB) that contains the
parameters for the verb being issued. The VCB
structure for each verb is described in Chapters 3, 4,
and 5. These structures are defined in the NOF API
header file nof_c.h.
Returned Values
The nof entry point does not have a return value. When the call returns,
the application should examine the return code in the VCB to determine
whether the verb completed successfully and to determine parameters it
needs for further verbs. In particular, when the CONNECT_NODE or
OPEN_FILE verb completes successfully, the VCB contains the
target_handle that the application should use when issuing subsequent
verbs.
Using the Synchronous Entry Point
Only one synchronous verb can be outstanding at any time for each
target handle. A synchronous verb fails with the primary return code
AP_STATE_CHECK and secondary return code AP_SYNC_PENDING if
another synchronous verb for the same target handle is in progress.
Asynchronous Entry Point: nof_async
An application uses nof_async to issue a NOF verb asynchronously. The
application also supplies a pointer to a callback routine. SNAplus2
returns control to the application immediately with a returned value
that indicates whether verb processing is still in progress or has
completed. In most cases, verb processing is still in progress when
control returns to the application. In these cases, SNAplus2 uses the
application-supplied callback routine to return the results of the verb
processing at a later time. In some cases, verb processing is complete