Re: Upgrade Informix version 5 to version 9

Anthony Burkitt wrote: > > My company has an application (compiled ESQL/C) running against Online > version 5. > In recent discussions, my management have been told by Informix that > there are no great problems porting from version 5 to version 9 (My > management appears to have been sold on the saleability of > Object-Oriented). > I do not know if Informix said (or implied this), or whether my > management is jumping to conclusions, but they are now under the > impression that we would probably not need to re-compiled the > application for such an upgrade. I find this a difficult concept to > believe. > > Could anyone out there confirm or deny this? > Some facts would be most useful at this point... WELLLLLLLLL.... You CAN run the 5.0 executables against a 7/8/9 server, however, since the 5.0 app expects to own a copy of the engine, ie the SQLEXEC process, and 7/8/9 engines are independent and the connectivity code was moved into the ESQL/C libraries, the 5.0 app will need to run the SQL Remote Module (sqlrm) as its SQLEXEC process. This is basically a protocol converter that lets 5.xx apps talk to local 7/8/9 servers. This works but is VERY slow. If the server and apps are not on the same machine the apps can continue to use the sqlexec client side program and access the 9.xx engine remotely with no performance penalty. You can recompile the 5.xx source with no modifications with the 9.xx ESQL/C it just will not take advantage of any 7/8/9 specific features. The advantage of this is that while you are porting your source and testing you can be running the 9.xx apps against the 5.xx server which works well (the app just treats the server as if it were a remote engine you just cannot use shared memory connections). This works so well that the 9.xx compiled apps will outperform the 5.xx apps running against the 5.xx server. Then once all apps have been recompiled and torture tested in production against the 5.xx engine the upgrade to 9.xx will be painless, at least from the application point of view, since the recompiled apps will have already been tested and verified. This is the upgrade method I use and recommend. Art S. Kagel