Re: Generic RPG File Handler for File I/O using OA

[Frank Kolmann <Frank.Kolmann@xxxxxxxxx>]

>  Thanks Nate
>
> I did not mean to imply RPGers at any time need any "redoing and 
> taking over all the work the compilers do for you" .
> Externalisation of file definitions is one of the key points of why 
> RPGILE is so easy to use.
> I am saying that to have a Generic RPG File Handler one needs to code 
> to retrieve the file layouts.
> I believe C imports data structures into the program from the external 
> file definitions, that need PRAGMA directives.
> For RPGers it is so simple they hardly think of what the compilers did 
> for them and they do not need to think of these things.
>
> Compared to RPG RLA the very fact you wrote wrappers is an order of 
> magnitude of complexity more than RLA.
> I doubt what you did is within the perview of your average RPGer.
> Using the _Rxxxxx functions from within RPG is IMO 2 orders of 
> magnitude more complex then RLA.
> And this is not even mentioning the complexities of NULL fields. Null 
> fields broke me.
> I am no longer working professionally , but to me sounds like OA I/O 
> is something like SPECIAL file in RPG.
> Never got into SPECIAL files.  Only time I used was on S/3 to print 
> out OCL to a report.
>
> There are many defininitions, of "lower lever", eg IRP, Intermediate 
> Code generated by the compilers.  I dont mean that.
> Regarding "lower level" I was mainly referring to Program Described 
> file access and UDDS data streams.
> In RPG one does not need to rely on external file descriptions. 
> External descriptions brought in a standardisation of sorts for us S/3 
> coders.
> On S/3 ,reading a program described db file meant you defined the file 
> layout in the I specs, and it did not need to match the actual file 
> layout. Many errors thus resulted.
> So extending that to be able to read any file was not so difficult.
> I doubt on Sys i ,anyone today uses Program Described db I/O, dont 
> even know if this is possible in Free Form RPG.
>
> fwiw on a S/3
>     . almost every job needed a file sorted. ADDROUT sorts were like 
> primitive LGL files.
>     . a record lock caused an instant crash of the job. S/38 record 
> lock waits were magic.
>
>
> Regards
> Frank
>
> On 26/06/2022 2:06 pm, Nathan Andelin wrote:
> > Frank,
> >
> > I appreciate your work and opinion. It seems that the participants in this
> > discussion may have different definitions for the meaning of "generic file
> > handlers". I'm not sure what they mean.
> >
> > In regard to getting involved in "lower level" database access and "redoing
> > and taking over all the work the compilers do for you", you're only
> > referring to RPG. IBM i C programmers rely on the _Rxxxxx functions
> > exported from service program QC2IO in order to access IBM i database
> > files. At least, that's what IBM recommends. Of course, RPG  has operation
> > codes. But the C routines are comparatively functional, and provide the
> > option of passing Library and File names as parameters, which are resolved
> > at runtime, which is more flexible than the traditional RPG interface. The
> > C functions pretty much mirror RPG operation codes. I wrote RPG wrappers
> > that streamline the API's to make it essentially equivalent to using RPG
> > operation codes.
> >
> >
> >
> >
> > On Sat, Jun 25, 2022 at 6:55 PM Frank Kolmann<Frank.Kolmann@xxxxxxxxx>
> > wrote:
> >
> > > Hi Nate
> > >
> > > I dont know Mahammad goals.
> > > My goal was to learn UDDS coding on S38. I did actually use UDDS once or
> > > twice in production.
> > > Plus I had a nice utility to view/update any file.
> > >
> > > My later goals were to learn how to use IBM APIs, I did, but I never
> > > used in production.
> > > Later I wanted to learn C, which I did, after learning C what I really
> > > gained was RPGILE was mostly a C based model.
> > > After learning C many things became clearer, procedures , prototyping ,
> > > pointers, modules and so on.
> > >
> > > Lastly I wanted to  transition my utility to the latest version of RPG.
> > > SQL made the utility redundant, but it is a way to learn.
> > > I failed because of the way NULL indicators are implemented, but learnt
> > > more  of Unix or is it C I/O functions to read SysI database.
> > > Unix I/O is orders of magnitude more complex than RPG, not sure the
> > > complexity is worth the results.
> > >
> > > Here I must mention my mentor, Scott Klement, without whose work I would
> > > never have progressed.
> > > The S38 UDDS work was all mine own effort.
> > >
> > > Finally my opinion on a Generic File Handler.  Yes I believe it is
> > > possible, but do you really want to get involved in the lower level
> > > detail of database access?
> > > You end up redoing and taking over all the work the compilers do for
> > > you, and it is not really possible to do as well as the system
> > > developers have already done.
> > > fwiw
> > >
> > > Cheers
> > > Frank