SMF APPC/MVS Data Transfer Elements
APPC/MVS enables program-to-program communication on a "peer- to-peer" basis. This cooperative processing support allows conversations between transaction programs (TPs) running anywhere in the SNA network.
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Once a conversation is established, the TPs can send and receive data using APPC services. Any TP executing in the MVS environment records the data sent and received, to and from the partner TP. If the TP is a batch job, TSO session, started task, or APPC/MVS ASCH scheduled TP, the data sent and received is recorded in the BATPGM, BAT_TS, BAT_ST, or BAT_TP file in the following data elements:
PGMDATAR
APPC Data Received (Bytes)
PGMDATAS
APPC Data Sent (Bytes)
If the TP is a batch job step, then a job-level observation will also be found in the BATJOB or BAT_JS file. The job- level data elements that record APPC data sent or received are:
JOBDATAR
APPC Data Received (Bytes)
JOBDATAS
APPC Data Sent (Bytes)
Finally, if the MVS TP is an APPC/MVS ASCH scheduled TP, the APPC/MVS Transaction File (BATATP) records contain the amount of data sent and received by the TP. Records appear in both the BAT_TP and BATATP file for the same execution of an APPC/MVS ASCH scheduled TP. Each BAT_TP record represents the address space perspective of a TP execution, while each BATATP record represents one invocation of a given TP.
In the case of multi-trans scheduled TPs, the TP remains in execution between conversations with requesting partner TPs. This means that a single BAT_TP DETAIL timespan observation can contain the cumulative resource measurements from many different conversations with various partner TPs. In the BATATP file, on the other hand, each observation contains the resource utilization of a single conversation with the requesting partner TP.
The APPC data sent and received by an ASCH scheduled TP is captured in the following BATATP file data elements:
ATPDATAR
Data Received (Bytes)
ATPDATAS
Data Sent (Bytes)
Duplicate accounting issues exist with the APPC Data Sent and APPC Data Received data elements. The data sent by one TP is data received by the partner TP. When both TPs execute in an MVS environment, SMF records document the sent and received metrics twice: once from the sending perspective, and once from the receiving perspective. This duplicity occurs in two BATATP observations when the APPC managed conversation was between two ASCH initiated TPs. It occurs in one BATATP and one BATPGM, BAT_ST, or BAT_TS observation (with the PGMDATAR and PGMDATAS data elements) when the APPC managed conversation was with an ASCH initiated TP allocated by a batch job, started task, or TSO session.
Charging only for data received or data sent would avoid the duplicity problem for conversations between two TPs executing in an MVS environment. When the conversation is between one MVS TP and another TP executing executing in a non-MVS environment (e.g., a PS/2 workstation or an AS/400), however, it would be valid to charge for both data sent and received on the MVS side if the partner TP environment did not support chargeback.
The issue is further complicated because a single TP can allocate multiple conversations with several different partner TPs. The multiple conversations can be spread across a number of different execution platforms: some that record data traffic and others that do not.
Careful consideration should be given to these duplicate chargeback issues before deciding to use the Data Received and Data Sent data elements as costing elements in the Batch Information Area files.