Re: MS SQL server access from RPG

Walden H. Leverich wrote:

Informix probably does not provide DDM access to its
data, so presumably only DRDA will be available to
access Informix SQL data;

And even if it did, how would you translate
RLL (chain/read) into SQL?
One statement per IO request?
Sure... that will perform well! :-)

Sure. But there would be no _requirement_ to convert a chain\read into SQL if Informix actually has\had DDM architecture support to access its SQL data. As a participant in DDM, then it should have keyed RLA support to whatever data being exposed. There may be /levels/ of support for the architecture where keyed access is a higher level of compliance but I am not aware. But RLA access is a feature of the DDM which would dictate that any DDM server be able to do that. Just as DB2 for i provides DDM access to its SQL data without converting those requests into SQL, so could Informix or any other database that wanted to expose its data via DDM.

DDM does not know SQL. DDM & DRDA are entirely different concepts, even if DRDA is built on top of DDM on i. They merely share some communication and data transport concepts. DDM provides RLA, and DRDA provides SQL access. DB2 for i provides both a DDM client and DDM server. IIRC there was a PC-based RPG that used the DDM to access database file data on the i, with the PC being a client and i the server. The RPG on i could use a DDM device *FILE as a client to access data in a homogeneous request or on any other system supporting DDM using the non-standard file naming for the target /data file/ that is to be accessed; e.g. a DDMFile could point to a file on a S/36 which provides support as a DDM server, exposing its DISK files.

Regards, Chuck