DFHZARR is called by DFHZARL to handle receive requests. This topic describes the
processing details of DFHZARR.
RECEIVE function
This function must be able to handle receipt of the following:
Application data
FMH7s and ER1s (negative responses)
PS_headers (Prepares, Request_commits)
Indicators such as CD, CEB, and RQD2
Signal
Figure 1 gives an overview of the modules involved with the processing of
receive requests. Figure 1. Distributed transaction processing of
LU6.2 receive requests
DFHZARL passes the DFHLUC parameter list, specifying the type of receive required, to
DFHZARR.
DFHZARR then performs the following actions:
Checks that request is valid; if not, returns error codes.
Initializes the application and LU6.2 receive buffers (by calls to DFHZARRA and the DFHZARR0
subroutine of DFHZARR respectively).
Calls DFHZARRC to determine what to process next.
Depending on the response from DFHZARRC, calls the relevant subroutine.
If enough (or all that can be) has not been received, loops back to step 3; otherwise step 6.
Tests for (and returns) signal when it has been received.
The results of the receive are passed back to the caller in the DFHLUC parameter list.
To control this processing, DFHZARR uses the variables receive_type and what_next,
as follows.
receive_type can have the following values:
RECEIVE_WAIT
Request was a receive and wait.
RECEIVE_IMMEDIATE
Request was a receive immediate.
LOOK_AHEAD
All the allowed user data has been received, but only one receive immediate call to the DFHZARR1
subroutine of DFHZARR is permitted to attempt to pick up indicators such as CD, CEB, or a
PS_header.
NO_MORE_RECEIVES
No more calls to DFHZARR1 are permitted, but processing may continue with what has already been
received.
NO_RECEIVE_LOOK_AHEAD
All the allowed user data has been received. An attempt must be made to pick up indicators such
as CD, CEB, or a PS_header without a call to DFHZARR1. This value is only required for a receive
immediate request.
RECEIVE_COMPLETE
Receive processing is finished.
The first two values are possible initial values of receive_type, and the other four are used as
the receive progresses.
what_next is an output of DFHZARRC, and represents what is next to be processed. It can
have the following values:
DATA_RECORD
Application data
FMH_RECORD
FMH7 in the buffer
PS_HEADER_RECORD
Prepare or Request_commit
PARTIAL_LL
First byte of a logical record only, therefore cannot tell whether it is a DATA_RECORD or
PS_HEADER_RECORD
