Re: LVLCHK *NO

[Jim Langston <jlangston@xxxxxxxxxxxxxxxx>]

Okay, so the gist of this is, it would take too much time and processor power
to dynamically link the files, and you think we want the extra check at run 
time.

The main advantage to dynamic linking is being able to change the underlying
database structure without having to recompile the program if no logic changes
have taken place, so it is easier to maintain our databases.

The main advantage to static linking is the system can open the programs faster,
and the program won't run if it fails the level check.  Although I think that 
the
way
RPG shotguns memory locations for files may come into play also.

Has anyone ever did a test on the added time and processor needed to be able
to link database files dynamically on the AS/400?

Regards,

Jim Langston

pytel@us.ibm.com wrote:

> It's not a fault, it's different paradigm.
> Record format is independent object. Database file uses it, HLL program uses 
>it
> (not only RPG - any other language).
> Level check is needed so that program could verify that it is using record
> format it thinks is using.
> If one wants to change physical file layout without recompiling programs, you
> have already answered your question - use logical files.
> If one wants to be able to use the very same program to process any file if 
>only
> it has fields NAME and SALARY - well, it maybe convenient, but I would 
>question
> usefullness of such approach.
>
> Advantages of "static linking" ?
> 1) consistency - the more checks are done at compile time, the less room for
> unpleasant surprise at runtime
> 2) efficiency - nobody cares about runtime efficiency on single-user PC, but
> this is still an issue on multi-user (multi-thousand user) systems
>
> Look at it from another point of view - the buzzword of today is OO. Record
> format is object class. C++ and Java do not allow to change class layout on 
>the
> fly. Nobody complains ... Moreover, ability to make as much static checks as
> possible at compile time are considered strong points (see p.1 above).
>
> Best regards
>     Alexei Pytel
>

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