Re: i/o module

On Wed, May 28, 2008 at 2:34 AM, David FOXWELL <David.FOXWELL@xxxxxxxxx> wrote:

Hi,

Does anyone have some code that they could post for externalizing file i/o operations ?

I've had my first go at this and although it works I'm not fully happy with it.

To replace an RPG CHAIN operation, my program does something like IF NOT ReadFile ( ), and the function ReadFile will do a CHAIN.

However in replacing a loop like

SETLL File

DOU %eof

READ File

ENDDO

I use another function that uses an SQL cursor. I realise that this last function could also do the same as the ReadFile ( ) , but should I replace a simple CHAIN by SQL?

I usually separate business logic from UI logic, which has
the effect of externalising I/O. I've got some notes on
encapsulating business logic in a service program
at:

pando.org/downloads/alsp.doc

Some notes describing how the UI component interacts
with the business logic (this is really a very simple
implementation of an MVC pattern) at:

pando.org/downloads/alspnotes.txt

Very incomplete; I don't know if they're helpful
to anyone other than myself.


Something curious about the above is that I/O
is discussed very little; since all the I/O is
encapsulated in private procedures it really doesn't
matter if it is native RPG or SQL (or even on
another machine, through ODBC/JDBC etc.)

The goal was to convert the business logic service
program to a batch transaction processor, so the
UI could be 5250, or a GUI (also avoiding a lot of
the 'interactive' tax). The code described in these
documents is currently running commercial
code (all file maintenance/inquiry for a suite of exit
point programs), but we were acquired and product
development halted before we could get to phase II.

Chris
--
The prisoner falls in love with his chains. -
Edsger W. Dijkstra