Re: Externalizing I/O was RPG read loops -- RPG400-L

I don't think that you really exempt the program in question from being 
retooled.  For example, let's take the jump from BPCS 405 to BPCS 6.  In 
that jump they changed the size of most all the fields.  Including such 
draconian items as Item number.  In an ERP system that's no small 
potatoes.  Your programs, at the very least, would have to be recompiled 
to take advantage of external data structures.  Unless, of course, you 
issued a systems edict that you were not to exceed the size of the old 
field, or take advantage of any other new file change, because you might 
have to recompile programs.

Or if you changed a key from packed to character you might have an issue 
with 
GetKey(MyPackedNbr);
In an existing program.

Something that can change from file, to data area, etc, might make sense 
to externalize.  And we do that with Company name.

Rob Berendt
-- 
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





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Re: Externalizing I/O was RPG read loops






Simple.  By doing it this way, you exempt the program in question from 
having to be retooled, recompiled, redistributed, and reintegrated into 
every user's system because of a file change.  Moreover, you could change 
the input from a file to a data queue, an Mq queue, IFS file,etc. in a 
manner completely transparent to the program in question.
 
Cheers,
Eric Filson

rob@xxxxxxxxx wrote:
Paul,

I think you're the first person that I heard of, that wasn't the person in 

charge of writing the access programs, that actually liked this scenario. 
Why an end developer would like to replace

chain(e) myfile;
// now actually do some real work with the fields

with
getFilename();
MyWorkField1=GetField(field1);
MyWorkField2=GetField(field2);
...
// now actually do some real work with the fields

rather escapes me.

Rob Berendt
-- 
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com





"Paul Morgan" 

Sent by: rpg400-l-bounces@xxxxxxxxxxxx
02/02/2005 10:18 AM
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Re: RPG read loops






Richard,

Great setup. I once contracted at a shop that did this with OPM programs
even before ILE. You never put a file into production without it's access
program. Applications programs never referred to a file directly but did
all access through the IO program. Even all the file logicals were in 
that
same program so you could select which logical to use with a parameter on
the call.

Paul

-- 
Paul Morgan
Senior Programmer Analyst - Retail
J. Jill Group
100 Birch Pond Drive, PO Box 2009
Tilton, NH 03276-2009
Phone: (603) 266-2117
Fax: (603) 266-2333

"Richard ECUYER" wrote

> I did it.
>
> For each file (physical, logical, with ot without key), i build one 
source
> with some procedures :
> Get_Filename (CHAIN)
> Set_filename (SET, LL, GT)
> Exists_filename (SETLL without read)
> Read_filename (READ, readp, readE, READPE)
> Insert_filename (write)
> Delete_filename (delete)
> Unlock_filename (unlock)
> Update_filename (update)
> dft_filename (populate the exported datastructure with
defaul
> values)
> All "READ" procedures include a parm (*on/*off) to lock or not the 
record)
>
> Create a module and one service pgm by file
> a ds (io_filename) is exported.
>
> It is not done by hand, i create a little pgm that get file decription 
and
> create all sources needed (procedure interface, module...)
>
> When i use suche a procedure, i include 3 lines :
>
> /copy of the bnddir (it is one with only IO service pgm)
> /copy of procedure interface
> an external DS (linked with the file) if i use data from the file.
>
> the only think (for me) to watch is in a loop that call a program that
read
> the same file i must make a setgt before the next read.
> all procedure return *off if request fald or *on if not.
>
> My loop are like this :
>
> Dow Read_filename (*off : '*NEXT' : '*EQ' : Key1 : Key2 ...)
> do staff
> Enddo
>
> One cool thing is that i can change the file (add new fields at the end)
> without getting level error (new field will not be usable until i
recompile)
> I have a performance gain, and all IO for a file are in ONE source.
> It is new for us, but all find it easy and pretty to use.
>
> My little piece of 0,1 euro.



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