SNAX/APC Application Programming Manual

Using the Application Program Interface
SNAX/APC Application Programming Manual—138786
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What You Must Do to Use Sync Point With
SNAX/APC
that affect the integrity of changes, and commits or backs out the changes as
determined by the sync point protocol to each protected resource.
•
Resynchronization TP: Resynchronization uses service transaction programs to
exchange sync point status among the LUs during an LU failure which might occur
during the sync point protocol, so that some LU never receives an expected LUW
status report. To recover from this case, the other LUs can wait until the failing LU
is reinitialized, and then the LUs perform a resynchronization protocol to complete
the sync point processing at each LU.
What You Must Do to Use Sync Point With SNAX/APC
The sync point support provided by SNAX/APC assumes that the user will supply all of
the sync point services that are not supplied in SNAX/APC. In this manual, these
services are called user-supplied sync point routines. The details of these routines are
given in the IBM manual, Systems Network Architecture, LU 6.2 Reference: Peer
Protocols (SC31-6808). The user-supplied sync point routines:
•
Provide a communication interface to their own clients requiring sync point services
(SPS)
•
Map their communication and sync point requests to SNAX/APC
•
Are responsible for:
•
Issuing all SNAX/APC verbs
•
Implementing the architected Resynchronization TP
•
Implementing the architected C-PRM component of the LU
•
Implementing the architected SPS component of the LU
The sync point support additions to SNAX/APC allow Customers to provide sync point
services over LU 6.2 conversations provided by the SNAX/APC LU 6.2 protocol stack.
They do not implement the architected sync point components and TPs necessary for a
complete sync point implementation.
Modifications required for sync point support in SNAX/APC are:
•
Changes to configuration and TP initiation
•
Changes to sync point session and conversation activation
•
Implementation of sync point verbs using presentation headers
•
Implementation of BACKOUT using SEND-ERROR
•
Resynchronization during BACKOUT
With sync point support, SNAX/APC ensures backward compatibility with the existing
SNAX/APC applications that adhere strictly to the IBM architecture for sync point
services.