TS/MP Management Programming Manual (G06.24+, H06.03+)

TS/MP Management Programming
NonStop TS/MP Management Programming Manual—540082-001
2-5
Sending Commands and Receiving Replies
Considerations When Opening PATHMON
When opening the PATHMON process programmatically, consider:
•
The PATHMON process can be opened by multiple user processes. The field
ZMAXSPI determines how many processes can request to use the SPI interface to
open the PATHMON process at the same time. Both a primary process and its
backup can open a PATHMON process simultaneously.
•
The PATHMON process should be opened for shared access; the AUTOSTOP
option is not supported.
•
SPI requesters should run as low PIN processes or named high PIN processes to
open the PATHMON process.
•
The NOWAIT depth must be either 0 (waited) or 1; a NOWAIT depth greater than 1
is not allowed.
•
SPI requesters should open the PATHMON process with a syncdepth of 1. If a SPI
requester opens the PATHMON process (using the Guardian OPEN procedure)
with a syncdepth of 1 and writes a request to that process and the primary process
fails, the operating system automatically directs the request to the PATHMON
backup process; the I/O error is invisible to the SPI requester.
A SPI requester can specify a syncdepth greater than 1 when it opens the
PATHMON process. However, the greater value has no effect because the
PATHMON process still handles requests one at a time.
•
A management application can have multiple concurrent opens to a single
PATHMON process.
Sending Commands and Receiving Replies
A management application uses the SPI procedures SSINIT, SSNULL, SSPUT,
SSPUTTKN, SSGET, SSGETTKN, SSMOVE, and SSMOVETKN to build a message
for the PATHMON process and to retrieve values from PATHMON’s response. (For
corresponding TACL procedures, see the SPI Programming Manual.)
The method you use to send and receive messages depends on the programming
language you choose to write your management application. Message transport is part
of the language you use to program your server; it is not part of SPI.
The management application also uses SPI to obtain event messages. The EMSGET
procedure extracts the elements (that is, tokens) of the messages, and the EMSTEXT
procedure obtains the text versions of the messages. For more information on event
management, see Section 7, ZPWY-MAP- Definitions in this manual and see the EMS
Manual.