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Hi,
Trigger programs have to be coded according to IBM's specs. The spec that
IBM published in the first V3R1 manual (when trigger programs first came
out) was wrong, because the individual that coded the RPG example didn't
know RPG. (Details, details...)
Here is an article that I wrote for the publication "Inside V3R1" many
years ago. I chose to write it in RPG III, as RPG IV was not yet well
accepted. I think that you can use this as a standard trigger shell. Be
sure to view the code in a non-proportional font:
I started out on a quest to create a universal shell for a trigger program
for RPG. I had a situation where there were two files, an order detail
file (named DETAIL) and a customer file (named CUSTFL with record format
CUSTFLR). The order detail file contains price and a quantity field. The
customer file contains the total amount on order for the customer.
A trigger program was the ideal solution, because I my order entry
system allowed updates to the order detail file through several different
programs. Either I would have to code my logic into each of these
different programs, or else write this logic once using the trigger
program.
When a trigger program is called, two parameters are passed to it. The
first parameter contains a data string containing all of the pertinent
information about the update to the file, and then contains the before and
after images and null byte maps of the file. If you hard code the "to" and
"from" positions for the file length, the program would have to be modified
every time a field length were changed in the program.
Instead, I used an image of the file in a data structure, and two other
"flat" data structures to hold the before and after images of the data.
You can access the data for either the before or after image by moving that
data structure into the externally defined data structure which specified
all the fields in the file.
A representation of the actual program has been shown in the figure
below. The "standard trigger shell" is shown bolded, and the custom code
for my application are shown in the lighter type. Note that the externally
defined file name is inserted on the "I" spec on line 4300.The two
subroutines are what do the arithmetic, and have been omitted.
Because the programs that update the order file do so repeatedly, I
have closed to not set LR on in the program. This means that I have to
plan in the writing of the application that all variables will not be
initialized on each new CALL.
100 H/TITLE -- UPDATE CUSTFL WITH AMOUNTS FROM ORDER DETAIL RECORD
--
200 F*
300 F* Copyright 1995, 2002 ? Barsa Consulting Group, LLC
400 F* 2900 Westchester Avenue
500 F* Purchase, New York 10577
600 F*
700 F* (914) 251-1234
800 F*
900 FCUSTFL UF E K DISK
1000 IQPARM1 DS 9999
1100 I* Physical file name/library/member
1200 I 1 10 QFNAME
1300 I 11 20 QLNAME
1400 I 21 30 QMNAME
1500 I* Trigger event ('1'-Insert, '2'-Delete, '3'-Update)
1600 I 31 31 QEVENT
1700 I* Trigger time ('1'-After, '2'-Before)
1800 I 32 32 QTTIME
1900 I* Commit lock level ('0'-*NONE, '1'-*CHG, '2'-*CS, '3'-*ALL)
2000 I 33 33 QCOMIT
2100 I* CCSID
2200 I B 37 400QCCSID
2300 I* Offset to the original record
2400 I B 49 520Q1ROFF
2500 I* Length of the original record
2600 I B 53 560Q1RLEN
2700 I* Offset to the original record null byte map
2800 I B 57 600Q1NOFF
2900 I* Length of the original null byte map
3000 I B 61 640Q1NLEN
3100 I* Offset to the new record
3200 I B 65 680Q2ROFF
3300 I* Length of the new record
3400 I B 69 720Q2RLEN
3500 I* Offset to the new record null byte map
3600 I B 73 760Q2NOFF
3700 I* Length of the new null byte map
3800 I B 77 800Q2NLEN
3900 IQPARM2 DS
4000 I B 1 40QLENG
4100 I/SPACE
4200 I* Externally defined data structure with each field name
defined
4300 IQFILE E DSDETAIL
4400 I* "Before image" of the file
4500 IQFILEB DS 4500
4600 I* "After image" of the file
4700 IQFILEA DS 4500
4800 C/SPACE
4900 C* Parameter list required for every trigger program
5000 C *ENTRY PLIST
5100 C PARM QPARM1 See DS
above.
5200 C PARM QPARM2 Not used
in pgm
5300 C* Using offsets and lengths provided get the before & after
images.
5400 C Q1ROFF ADD 1 Q 50 Before
offset
5500 C Q1RLEN SUBSTQPARM1:Q QFILEB Get befor
image
5600 C Q2ROFF ADD 1 Q After
offset
5700 C Q2RLEN SUBSTQPARM1:Q QFILEA Get after
image
5800 C/SPACE
5900 C QKEY KLIST Customer
file
6000 C KFLD CUST# key list.
6100 C/SPACE
6200 C QEVENT IFEQ '2' Delete
Record
6300 C QEVENT OREQ '3' Update
Record
6400 C MOVELQFILEB QFILE Get befor
image
6500 C QKEY CHAINCUSTFLR 05 Get
customer
6600 C *IN05 IFEQ *OFF record
& sub
6700 C EXSR SUB out
order
6800 C UPDATCUSTFLR
amounts.
6900 C ENDIF *IN05
IFEQ *OFF
7000 C ENDIF QEVENT
IFEQ '1'
7100 C/SPACE
7200 C QEVENT IFEQ '1' Insert
Record
7300 C QEVENT OREQ '3' Update
Record
7400 C MOVELQFILEA QFILE Get after
image
7500 C QKEY CHAINCUSTFLR 05 Get
customer
7600 C *IN05 IFEQ *OFF record
& add
7700 C EXSR ADD in
order
7800 C UPDATCUSTFLR
amounts.
7900 C ENDIF *IN05
IFEQ *OFF
8000 C ENDIF QEVENT
IFEQ '1'
8100 C/SPACE
8200 C RETRN Return
8300 C/SPACE 2
8400 C ADD BEGSR
To start the trigger function the following three commands have to be
executed:
ADDPFTRG FILE(DETAIL) TRGTIME(*AFTER) +
ADDPFTRG FILE(DETAIL) TRGTIME(*AFTER) +
TRGEVENT(*DELETE) PGM(program-name)
TRGEVENT(*INSERT) PGM(program-name)
ADDPFTRG FILE(DETAIL) TRGTIME(*AFTER) +
TRGEVENT(*UPDATE) PGM(program-name)
TRGUPDCND(*CHANGE)
Al
Al Barsa, Jr.
Barsa Consulting Group, LLC
400>390
914-251-1234
914-251-9406 fax
http://www.barsaconsulting.com
http://www.taatool.com
Bill Erhardt
<ERHARDT@BaldwinHQ To: "'Mid Range list -
Questions'" <MIDRANGE-L@midrange.com>
.com> cc:
Sent by: Subject: V5R1 - and Trigger
Programs
midrange-l-admin@m
idrange.com
11/08/2002 10:12
AM
Please respond to
midrange-l
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We've just installed V5R1 and now have problems with trigger programs.
I've
heard that the parameter has changed but how? I've gone to the infocenter
and found the trigger buffer section but this doesn't seem correct.
Bill Erhardt
Baldwin hardware
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