"why haven't the MV DBMS vendors created a READUO"

Possibly in part because of the need to then have resolution mechanism for when 
2 processes change the same data (assuming of course that the data wasn't, say, 
an accumulation total) --> what interface would you use .... telnet will not 
work nicely with the web app described, nor with someone using, say UOJ

Still, extend a bit, and it could throw an error with the differences to be 
handled by "whatever" application layer --> but of course the real kicker in 
all of this is, and always has been, the wealth of legacy code that WOULDN'T 
use the new mechanism without a major rewrite .... and if you get to THAT 
point, refer to "why U2" thread :-(



Ross Ferris
Stamina Software
Visage > Better by Design!

-----Original Message-----
From: u2-users-boun...@listserver.u2ug.org 
[mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Tony Gravagno
Sent: Thursday, 14 July 2011 8:46 AM
To: u2-users@listserver.u2ug.org
Subject: Re: [U2] Record Locks - How long should they last for? (Opinion)

After all of these years, why o why haven't the MV DBMS vendors created a 
READUO mechanism which allows us to optimistically lock records in exactly the 
way that George, Rex, and a hundred other app developers have indicated over 
the last 15 years?

Design tip: For all new development, abstract your file IO and all OS access 
into separate functions, Includes, and/or subroutines, away from the business 
code.  This way you can change your datastore interaction without messing with 
your application logic, and you can re-use the routines for a lot of different 
work.  The application needs to be aware of whether you're moving forward with 
a pessimistic or optimistic lock, but your app code shouldn't have to manage 
those mechanisms.

T

> From: George Gallen
> ... instead of the checksum token method, I was going to write the 
> record to a holding file with an ID that was a combination of 
> file/record/transaction token
> 
> And do a comparison using the saved item to see if record changed, but 
> only if the record lock had expired - I still wanted to keep the locks 
> since the system could be used by local users as well, which is easier 
> using the READU locally to test for locking.

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