Immediate CMRCV Response Also Trace the Buffer (153524)

CAUSE

If you are writing a CPI-C application, you can define whether you like to use a blocking or nonblocking conversation. In case of a blocking operation, a call will be returned when the requested operation is complete (synchronous call). In the case of a nonblocking call, the call will be returned immediately after the operation is initiated (asynchronous call).

In a CPI-C application this can be done using the CPI-C API call Set_Processing_Mode (cmspm) where you can specify the receive Types as CM_BLOCKING or CM_NON_BLOCKING. This indicates that all subsequent calls will be returned either synchronous or asynchronous, accordingly.

If you are using asynchronous calls the receive request call, CMRCV will return immediately with a CMRECV response with CM_INCOMPLETE_DATA_RECEIVED. Although the data returned is not complete, the SNA Trace utility is tracing that buffer. This might be confusing when you analyze the CPI-C API traces.

With the SNA Applications: CPI-C trace enabled, you may see the following:

CPIC   CMRCV request
CPIC    Conversation ID = 01000000
CPIC    Requested length = 4096
CPIC   Conversation characteristics
CPIC    Conversation type = CM_MAPPED_CONVERSATION
CPIC    Fill type = CM_FILL_LL
CPIC    Receive type = CM_RECEIVE_AND_WAIT
CPIC   ---------------------------------------------- 13:34:40.23
CPIC   CMRCV response, result = CM_OPERATION_INCOMPLETE
CPIC   ---- Buffer at address 002F27A0 ----
CPIC   B8002F00 B8002F00 00000000 00000000     <../.../.........>
CPIC   00000000 00000000 00000000 00000000     <................>
CPIC   00000000 00000000 00000000 00000000     <................>
CPIC   00000000 00000000 00000000 00000000     <................>
CPIC   00000000 00000000 00000000 00000000     <................>
CPIC    Data received type = CM_NO_DATA_RECEIVED
CPIC    Received length = 6625328
CPIC    Status received = ***UNKNOWN STATUS_RECEIVED***
CPIC    Request to send received = ***UNKNOWN REQ_TO_SEND TYPE***
				

The CNMRCV response shows no data. This is also reported in the Data received type field which returns CM_NO_DATA_RECEIVED.