RE: Event driven was Re: Hmmmm.....$1 Billion

["Elvis Budimlic" <ebudimlic@xxxxxxxxxxxxxxxxxxxxxxxxx>]

It's been a few years since I took the operating system course, but I
believe software and hardware interrupts are the guts of truly event-driven
model.  Some OSs simulate interrupts with never ending loop with a large
if-else (switch) statement.
However, when you start talking interrupts the next logical question is 'can
interrupt be interrupted'.  Answer is yes, but then how many levels deep you
want this to go?
It's all doable and there are many OSs that do it.  
I must claim ignorance as to if and how 400 interrupts function on the 400
as at the level I code I don't really need to know.  
I have coded some threads on the 400 but always in batch jobs obviously.
Trickiest part was ensuring that all the underlying apis, commands etc. that
my threads would use are also threadsafe.  Lets just say I learned to read
fine manuals for every OS function and learned to hate the word
'Conditional'.

Elvis

-----Original Message-----
 To: Midrange Systems Technical Discussion
Subject: Event driven was Re: Hmmmm.....$1 Billion

How does one simultaneously do a data queue operation and a screen read? 
VARPG (from what I've heard) supports event driven stuff, but not RPGILE. 
For example, the user is on a screen, but then another event comes in 
(let's say a critical update from a shop floor counter) and it needs to 
update the screen.  Traditionally your RPG or COBOL is waiting on the read 
of the screen and is not checking the data queue at the same time.

Rob Berendt