Re: S/36 MRT programs (some questions)

[Pete Hall <peteh@xxxxxxxxxx>]

At 08:46 PM 1/14/98 -0500, Marc Zylka wrote:
>I'm looking at changing our MRT programs to be SRT programs and I have some
>questions (they're running on the AS/400 in the 36 environment):
>
>1) I have removed the display file keywords such as KNUM, WSID, etc.   I've
>also
>removed the REL workstation opcode.  Is this usually sufficient?

Marc,

"Usually" is not applicable. It depends entirely on the coding style of the 
program. See #3

>2) I'm trying to understand how an MRT program works.  Does it, for every
>cycle,
>process whichever workstation has requested a unit of work?

One workstation at a time can run through the cycle. All other requesters who 
have pressed the enter key, wait on queue.

>3) Is there anything to watch out for during this change?

There are a few things.

Since all MRT requesters share the same file cursors, you may have trouble with 
records being left locked. Make sure that record locks are always released. 
Control records that contains a values that are updated frequently can cause 
problems. Also beware of deadlock situations. 

Sometimes variables are omitted from the save data structure or shared 
indicator array. This could be because their initial state is insignificant, 
but it could also be because the variable is used to communicate between all 
attached sessions. Next invoice number, next record number, etc. You need to 
figure out the usage of each field that is not defined in the save data 
structure and each indicator that is not saved. You may need to use a shared 
user space or data area to provide interprocess communication, and if you do, 
you'll need to either explicitly move values to/from it, where this had been 
handled implicitly before, or pass pointers to the external shared data space 
and synchronize the access to it, thereby emulating the behavior of the MRT in 
your code.

hth
Pete


Pete Hall
peteh@inwave.com 
http://www.inwave.com/~peteh/

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