The following illustration represents the Dialog Flow Diagram for a batch process-implementing procedure named Batch Maintenance. This procedure handles checkpointing and restart at last checkpoint.
Dialog Flow Diagram - Batch Maintenance
A fully commented Procedure Action Diagram for the procedure Batch Maintenance is represented in the following sample code.
Procedure Action Diagram - Batch Maintenance (Part 1)
BATCH_MAINTENANCE
IMPORTS: Work View returned_from_transfer work
EXPORTS: Work View sent_through_transfer work
LOCALS: Work View restart work
Work View target work
Work View returned work
Work View returned customer
Work View commit ief_supplied
Work View message work
EXIT STATE IS requested_operation_complete
NOTE
... FIRST, check to see if this is a RESTARTED procedure. If the number
written to the restart file by WRITE RESTART RECORD in a previous
execution is greater than zero, it means that BATCH MAINTENANCE
previously failed in mid-execution.
IF returned from transfer work restart_count IS EQUAL TO 0
USE get_restart_number
WHICH EXPORTS: Work View target_work
NOTE
Get RESTART NUMBER is an external action block which reads the restart
file (written by WRITE RESTART NUMBER at the end of the action block). It
passes back a value of zero if the restart file is empty.
NOTE
GET TRANSACTION is an external action block that reads a sequential file
of CUSTOMERS. It returns CUSTOMER details (in RETURNED CUSTOMER) and a
request code (in RETURNED WORK).
Possible values of REQUEST TYPE are:
- A=Add (CREATE) this customer
- C=Change (UPDATE) this customer
- D=Delete this customer
- E=End of input file reached
USE get_transaction
WHICH EXPORTS: Entity View returned customer
Work View returned work
NOTE
... NEXT. If we are restarted, spin through the transaction
file until you get to the first one that was not processed
properly the first time.
Procedure Action Diagram for Batch Maintenance (Part 2)
WHILE restart work restart_count IS LESS THAN target work
restart count
AND returned work request_type IS NOT EQUAL TO E
SET restart work restart_count TO restart work
restart_count + 1
USE get transaction
WHICH EXPORTS: Work View returned work
Entity View returned customer
NOTE
... NOW, you must be positioned at the first customer transaction not yet
processed. If this is not a restarted execution, that will be the
first transaction on the input file; if it IS a restart, it will be
the transaction right after the last one for which a commit took
place.
WHILE commit_ief_supplied count IS LESS THAN 100
AND returned work request_type IS NOT EQUAL TO E
EXIT STATE IS requested_operation_complete
SET message work result TO OPERATION COMPLETED
NOTE
CREATE CUSTOMER, UPDATE CUSTOMER, and DELETE CUSTOMER are Elementary
Processes for which Process Action Diagrams were created during BAA.
CASE OF returned work request_type CASE A
USE create_customer
WHICH IMPORTS: Entity View returned customer
IF EXIT STATE IS NOT EQUAL TO
requested_operation_complete
SET message work result TO NOT ADDED
CASE C
USE update customer
WHICH IMPORTS: Entity View returned customer
IF EXIT STATE IS NOT EQUAL TO
requested_operation_complete
SET message work result TO NOT CHANGED
Procedure Action Diagram for Batch Maintenance (Part 3)
CASE D
USE delete customer
WHICH IMPORTS: Entity View returned customer
IF EXIT STATE IS NOT EQUAL TO
requested_operation_complete
SET message work result TO “NOT DELETED”
NOTE
WRITE MESSAGE is an external action block that writes a result message to
a message file it forms the message based on REQUEST TYPE (in RETURNED
WORK), the details in RETURNED CUSTOMER and RESULT (in MESSAGE WORK).
USE write message
WHICH IMPORTS: Entity View returned customer
Work View message work
Work View returned work
SET commit_ief_supplied count TO commit_ief_supplied_count +1
USE get_transaction
WHICH EXPORTS: Entity View returned customer
Work View returned work
IF returned work request type IS EQUAL TO e
SET sent_through_transfer work restart_count TO 0
ELSE
SET sent_through_transfer_work restart_count TO
returned_from_transfer work restart_count +
commit_ief_supplied_count + restart work
restart_count
EXIT STATE IS process_commit
SET target work restart_count TO sent_through_transfer
work restart_count
NOTE
WRITE RESTART NUMBER is an external action block that records the number
of input transactions for which database updates have been committed.
USE write_restart_number
WHICH IMPORTS: Work View target work
...
NOTE
WRITE RESTART NUMBER is an external action block that records the number
of input transactions for which database updates have been committed.
USE write_restart_number
WHICH IMPORTS: Work View target work
The views used by Batch Maintenance are presented in the following sample code. Note that the technique for using external action blocks for sequential file processing is also illustrated in these samples.
View Definitions for Batch Maintenance
Import View
----------------------------------------------------------------------------
View RETURNED_FROM_TRANSFER of work group WORK Attributes:
RESTART_COUNT
----------------------------------------------------------------------------
Export Views
----------------------------------------------------------------------------
View SENT_THROUGH_TRANSFER of work group WORK Attributes:
RESTART_COUNT
----------------------------------------------------------------------------
Local Views
----------------------------------------------------------------------------
View RESTART of work group WORK Attributes:
RESTART_COUNT
View Target of work group WORK Attributes:
RESTART_COUNT
View RETURNED of work group WORK Attributes:
REQUEST_TYPE
View RETURNED of entity CUSTOMER Attributes:
NUMBER
NAME
STATUS
CREDIT_RATING
BILL_TO_ADDRESS_LINE_1
BILL_TO_ADDRESS_LINE_2
BILL_TO_ADDRESS_LINE_3
BILL_TO_CITY
BILL_TO_STATE
BILL_TO_ZIP
View COMMIT of work group COMPOSER_SUPPLIED Attributes:
COUNT
View MESSAGE of work group WORK Attributes
RESULT
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