NET/MASTER Network Control Language (NCL) Programmer's Guide

Pathway, NonStop NET/MASTER MS, and NCL
Working With Pathway Server Classes
106160 Tandem Computers Incorporated 15–5
A PATHSEND requester includes two Guardian procedure calls that enable
PATHSEND requesters to communicate with Pathway server classes:
The SERVERCLASS_SEND_ procedure enables PATHSEND requesters to send
data to and receive replies from a Pathway server class.
The SERVERCLASS_SEND_INFO_ procedure enables PATHSEND requesters to
get detailed information about the last SERVERCLASS_SEND_ operation.
Refer to the Pathway Application Programming Guide for more information about
PATHSEND, and the SERVERCLASS_SEND_ and SERVERCLASS_SEND_INFO_
procedures calls.
Not shown in Figure 15-1, because it is not a Pathway process, is the LINKMON
process. LINKMON is part of the PATHSEND interface. Just as a TCP supports
access to Pathway server classes from requesters written in SCREEN COBOL, so
LINKMON supports access to Pathway server classes from a PATHSEND requester.
Refer to the Pathway Application Programming Guide for more information about
LINKMON.
Using NCL Processes as
PATHSEND Requesters
As shown in Figure 15-1, you can write an NCL procedure to act as a PATHSEND
requester. From an NCL PATHSEND requester, you do not explicitly use the
SERVERCLASS_SEND_ and SERVERCLASS_SEND_INFO_ procedure calls to
communicate with a server class. Instead, an NCL PATHSEND requester uses the
PSEND verbs to communicate with Pathway server classes.
From an NCL PATHSEND requester, the PSEND SEND verb transparently uses the
SERVERCLASS_SEND_ and SERVERCLASS_SEND_INFO_ procedure calls to
perform its operation. The PSEND SEND verb first uses the SERVERCLASS_SEND_
procedure call to send a request message and to receive a reply message from a
Pathway server class. Both the request message and reply message can be sent as
mapped or unmapped, using the variable(s) you specify.
If the SERVERCLASS_SEND_ procedure completes with return error 0 or 233, the
PSEND SEND verb then uses the SERVERCLASS_SEND_INFO_ procedure to get
information about the error. Information is then made available to the NCL process in
the &SYS.PSEND and &SYSMSG variables.
Refer to the Pathway Application Programming Guide for more information about
PATHSEND, the SERVERCLASS_SEND_ and SERVERCLASS_SEND_INFO_
procedures calls, and SERVERCLASS_SEND_ return errors. The PSEND SEND verb
and the &SYS.PSEND and &SYSMSG variables are discussed later in this section.
Using Panels for Screen
Displays
Using Pathway requesters written using languages other than NCL, such as SCREEN
COBOL, you can design screen displays through which users can interact with
Pathway server classes.
Using NonStop NET/MASTER MS, you can design screen displays by using the panel
control language. As shown in Figure 15-1, an NCL PATHSEND requester can use a
panel description file to display a panel through which users can communicate with a
Pathway server class.