Re: Multi Tiered ODBC

"Weiqi Gao" <weiqigao@crl.com> wrote: >> In article <327DE5D2.57DD@businessobjects.com>, >> wmartin@businessobjects.com wrote: >> >> > I would love to hear some feedback from anyone who has had experience >> > using a multi tiered ODBC solution ... >Please be aware that the word "multi-tier" means something quite different >when applied to ODBC. A two-tiered ODBC corresponds to a flat file >database. A three-tiered ODBC corresponds to the old two-tiered >client/server (application<->ODBC driver<->RDBMS). And in general, >whenever the ODBC documentation mentions the word "tier", no "three-tiered >client/server application" meaning is intended. I beg to differ. A simple ODBC driver on top of a flat file system is referred to as a single-tier driver by driver developers I know. A two-tier ODBC system is an ODBC driver that connects to a server, usually via a protocol proprietary to the server vendor (e.g. a Sybase ODBC driver based on CTLIB). A three-tier "driver" is something like SimbaExpress, where a lightweight client driver connects to an ODBC SERVER on another platform; that ODBC server (via the driver manager) loads ODBC drivers which typically are two-tier. Why go to all that trouble? It's a lot easier to install a single all-purpose client driver on a hundred networked workstations, and administer the heavyweight installs of Oracle, Sybase and what-have-you drivers on a single platform, than to install SQL*Net and Sybase CTLIB .DLL's everywhere . >Targetting multiple RDBMSs with ODBC sounds like a noble thing to do, but >doesn't offer any advantage to the corporate developers who have endured a >painful process of selecting their RDBMS very carefully. ODBC lets you plug new applications (Crystal Reports, Access, Impromptu) into old databases. It lets you combine different data sources that "just grew that way" in different environments. For example, I can join local Access tables to Sybase tables on my servers and C-ISAM files from my legacy SFAS system, with barely a thought to where each table is. I agree, nobody keeps switching databases for a single system. But you inherit a lot of stuff you'd rather not get too intimate with, and can be thankful when you can pick and choose Windows tools that all talk the same language even if the underlying data is baroque ("Quick, put a GUI on our VSAM files") Engineers believe that the equations approximate reality. Physicists believe that reality approximates the equations. Mathematicians never make the connection.