RE: SQL data access

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx 
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Shannon 
O'Donnell
Sent: Thursday, October 19, 2006 4:31 PM
To: Midrange Systems Technical Discussion
Subject: RE: SQL data access

I'm not familiar with using DDM to access an SQL database 
such as MySQL.
Is that even possible?  That would be really cool if it is and I will
have learned something new if you could share your solution 
for how this
works.

AFAIK, MySQL doesn't currently support the DRDA protocol.  

But since mySQL is open source and the DRDA specs are published, it
could be added.  Might make a nice winter project. <grin>

What I meant in terms of overhead performance, was that if you have to
add another software package in the middle there, just to create a
pipeline to the SQL database and then format that data into a 
file that
could be referenced using an F-Spec in an RPG program...that 
you'd have
a potential application performance issue there because of all the
intervening middleware. 

I didn't think I had to spell it all out. I assumed that 
list-ees would
be able to reason out the logic on their own. My mistake.

While I agree that the middleware adds overhead, I disagree that the
overhead is higher than what you'd see using the other methods.  

All I'm saying is that DDM files between an iSeries and another DB2
database performs quite well.  If you could do DDM to a non-DB2
database, there's no reason it couldn't perform just as good.

IBM (and Oracle) charges big $$$ for the middleware piece in question, I
have to assume they have spent some time optimizing the performance.
Actually, the Oracle middleware runs on the iSeries itself, whereas the
IBM middleware runs on an external PC.

I wonder what IBM would do if mySQL supported DRDA and you could use it
as a free and reasonably performing alternative to IBM WebSphere
Information Integrator.

Lastly, as I write this, I must admit that in the back of my mind I'm
recalling that the Oracle Transparent Gateway product didn't support DDM
files and RPG native I/O.  You had to use embedded SQL and the CONNECT
TO statement.  However, I might not be remembering correctly.  IBM's
product might or might not have the same limitation.  Certainly, they
don't have to have that limitation as DRDA between DB2 databases support
RLA using DDM.  

Charles Wilt
--
iSeries Systems Administrator / Developer
Mitsubishi Electric Automotive America
ph: 513-573-4343
fax: 513-398-1121