Re: successful migration from client/server to 3 tier systems ?

I said:

> From a performance point of view, TPC-C configurations share an
> important 3-tier characteristic: the distribution of client load across
> "front end" processors. This is true even though TPC-C doesn't define
> a full 3T logic. For that matter, even some 1-tier (host/mainframe)
> environments share this offloading characteristic. While they may not
> be your cup of tea, MVS mainframes scale darn well, thank you very
> much!

1. Singh <asingh_at_infinet.com> asks:

> How does a front-end processor make it 3-tier. Physically there may be
> only two tiers - the front end and the back end running and between them
> they can run all of the application for TPC-C. This may give you a "fat
> client" but, I think, it is still 2-tier. Logically it may be 3-tier but
> then you can get logical 3-tier on MVS mainframe also.

A front-end processor does >not< make it 3T. I don't mean to call TPC-C a 3T application, because logically it's not. The point is that FEPs, be they in TPC benchmarks or in traditional mainframe designs, remove load from systems higher in the pipeline, such as the DBMS server(s). This offloading is the same characteristic that makes multi-tier client/server more attractive from the scalability perspective.

--
Jonathan Eunice
Analyst, client/SERVER Companion