COBOL Manual for TNS and TNS/R Programs

Environment Division
HP COBOL Manual for TNS and TNS/R Programs—522555-006
6-71
RECEIVE-CONTROL Paragraph
In the COBOL85 environment, if the RECEIVE-CONTROL paragraph’s TABLE
OCCURS phrase includes EXTENDED-STORAGE, the reply table is in the Extended-
Storage Section.
In the CRE, if the reply table exceeds an internal threshold value, the reply table is in
the Extended-Storage Section.
Reply messages saved in the reply table are identified by their requester process.
These messages correspond to and answer the specific requester.
For example, if REQUESTER PROCESS 3 in Figure 6-1 failed before it received
REPLY MESSAGE 5, and its backup reissued the request based on the checkpoint
information, the COBOL fault-tolerant facility would recognize that the request was
performed. It would reissue REPLY MESSAGE 5 to REQUESTER PROCESS 3
without re-executing the request.
If a Receive-Control paragraph has no reply table (no SYNCDEPTH LIMIT and REPLY
CONTAINS clauses), then replies are not saved. The fault-tolerant facility cannot
retransmit them. If a requester’s backup process retransmits them, they are not
recognized as duplicate requests, because the originals were not saved. Responding
to duplicate messages can corrupt the database.
Note. You do not need a reply table if the requester is not a fault-tolerant process.
Figure 6-1. Reply Table
Entry length is defined by reply-length
or file-name
REQUESTER PROCESS 1 REPLY MESSAGE 1
REQUESTER PROCESS 1 REPLY MESSAGE 2
REQUESTER PROCESS 2 REPLY MESSAGE 6
REQUESTER PROCESS 2 REPLY MESSAGE 7
REQUESTER PROCESS 3 REPLY MESSAGE 4
REQUESTER PROCESS 3 REPLY MESSAGE 5
Number of entries is defined by
table-length * sync
Number of replies per
requester is defined by
sync
.
.
.
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