TS/MP 2.5 Management Programming Manual

across a network, a maximum of five characters is allowed—a dollar sign followed by four
alphanumeric characters (for example, $abc2).
#ZSPI identifies the application as using the SPI interface and directs the PATHMON process to
process requests and replies using the SPI procedures.
Considerations When Opening PATHMON
When opening the PATHMON process programmatically, consider:
• The PATHMON process can be opened by multiple user processes. The field
“ZMAXSPI” (page 79) 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 be opened for shared access; the AUTOSTOP option is not supported.
• SPI requesters 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 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 handles one request
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 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 “ZPWY-MAP-
Definitions” (page 75) and the EMS Manual.
Figure 6 (page 27) illustrates the commands sent and the responses received when configuring a
Pathway subsystem.
26 TS/MP Management Programming