Re: ILE Conversion

["Peter Dow" <pcdow@xxxxxxxxx>]

Am I missing something? You say that "If you externalize your database
interface, you can change the database without having to change the
applications." As near as I can tell from your discussion of the file server
program, that's only true if you are talking about adding new fields at the
end of the record. If fields are rearranged, if an existing field expands or
contracts, if new key fields are inserted in the key list, I would think the
application programs would have to be revisited. Am I wrong?

Peter Dow
Dow Software Services, Inc.
909 425-0194 voice
909 425-0196 fax


From: Richard Jackson <richardjackson@richardjackson.net>
> Potential Conclusion
>
> If you externalize your database interface, you can change the database
> without having to change the applications.  That is good.  If you build
your
> applications so that business logic uses the database interface you built,
> for the same reason they are also partially protected from database
changes.
> If you build your applications using frameworks where the framework puts
up
> screens then calls the business logic you can have a framework for an
> interactive app and another framework for a batch app and not have to
> rewrite anything.  If you reach that point, you can add support for web
> activities and EDI activities very rapidly and with very low cost.
>
> In the previous paragraph please note that your applications are largely
> independent of the external user interface and that all of the value in
your
> solution is in three places: the framework, the business logic, and the
> database schema - with most of it in the last two.  That is where it
belongs
> and, in my opinion, that fact justifies the both direction and the effort
to
> reach the goal.
>
>
> Richard Jackson
> mailto:richardjackson@richardjackson.net
> www.richardjacksonltd.com
> Voice: 1 (303) 808-8058
> Fax:   1 (303) 663-4325
>
> -----Original Message-----
> From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
> Behalf Of boldt@ca.ibm.com
> Sent: Tuesday, July 04, 2000 7:13 AM
> To: RPG400-L@midrange.com
> Subject: Re: ILE Conversion
>
>
>
>
> Mark wrote:
> >I have been assigned the task of converting a HUGE monolith of a program
> >into more manageable pieces. I have been working with RPG IV now for
about
> >4 years and have been creating small ILE programs utilizing
> sub-procedures,
> >service programs, and the rest of that good stuff for about a year. This
> is
> >the first very large project I will be attempting and I have a few
> >questions.
> >
> >Regarding screen handling: The current program maintains 10 screens in
one
> >display file. Would it be advantageous to place each display format in
> it's
> >own display file or to continue to place all of the screens in one
display
> >file and just maintain each format in it's own module.
> >...
>
> Screen handling is a tricky subject.  Like many others here, you too
> may someday have to deal with the issue of "web-enabling" your
> application.  Web applications have a much different user interface
> model than your typical monolithic AS/400 application.  In particular,
> web apps are driven by the web server, and not by the application
> itself.  If you've done any CICS programming or S/36 MRT programming,
> you should be comfortable with web programming concepts.
>
> When restructuring your app, anything dealing with the user interface
> should be separated out into separate modules.  The business logic
> preferably should be restructured into a set of procedures that can
> be called in "batch" mode with no global data within the procedures.
>
> There's more to it than that, obviously, but hopefully you'll start
> thinking about UI-logic separation when restructuring your code.
>
> (Note that web-based programming is a major focus for us in the
> Toronto Lab, and hopefully in the future you'll see some easier ways
> to web-enable your apps.)
>
> Cheers!  Hans
>
> Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com
>
>
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