SNAX/APC Application Programming Manual

Using the Application Program Interface
SNAX/APC Application Programming Manual—138786
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Version Levels of the IPC Header
If the SNAX/APC TP is a target TP (not the originator of the conversation), when the
TP-READY verb completes, the TP should issue a GET-TYPE verb and continue with
the appropriate verb set. However if the conversation type is mapped, SNAX/APC will
allow the local TP to issue basic verbs in a mixed-mode conversation.
Using mixed-mode conversations requires additional coding in the SNAX/APC TP.
SNAX/APC simply passes any received data, including any special mapped
conversation GDS variables, to its TPs. The SNAX/APC TP must take appropriate
action in response to these variables.
Some possible GDS IDs that a remote, mapped conversation TP can issue are:
X'12F3' Map Name
X'12FF' Application Data
X'12F2' User Control Data (FMH)
X'12F4' Error Data
X'12E1' Error Log
X'12F1' Null Structured Data
SNAX/APC TPs that receive these GDS IDs might need routines to take appropriate
action. With the exception of the Application Data ID (%H12FF), which is normally
expected in basic conversations, occurrence of these GDS variables can be minimized by
careful TP application design. Receipt of these variables by the SNAX/APC TP can be
either ignored or reported back to the remote TP as errors, depending on your
application needs.
Version Levels of the IPC Header
The IPC version code is the mechanism SNAX/APC uses to distinguish between
versions of the UOWs (verbs) available to the TP. The version code is carried in the IPC
header and so applies to all UOWs in the IPC.
IPC Version Codes
Currently, four version codes are available: S1, S2, S3, and S5 (S4 is reserved for future
use). S5 adds sync point service support. You are encouraged to use S5 because it
provides all earlier capabilities plus sync point support. Most SNAX/APC verbs
currently behave the same whether issued at S1, S2, S3, or S5 levels. The following are
the exceptions:
ALLOCATE and MC-ALLOCATE
If either of these verbs is issued with IPC version code S3, conversational security is
permitted. Conversational security allows a program-supplied user ID and password
when a SNAX/APC transaction program allocates a conversation. If you want to
implement conversational security, you should use IPC version code S3 for the
entire conversation, not just the ALLOCATE or MC-ALLOCATE verb. The S3
request formats for the ALLOCATE and MC-ALLOCATE verbs are detailed in
Section 3, Verb Definitions
.