Re: Application design

The 4-tier application architecture, while not exactly common, has been
around for quite awhile.  It is typically described as:

Data Tier:  Data storage processes.
Data Centric Tier:  Data manipulation processes
User Centric Tier:  Data/Business rule integration Ppocesses
Presentation Tier:  Presentation processes.

A good textbook on the subject matter is entitled "Enterprise Application
Architecture", published in 1999 by Wrox Press Ltd. The author is Joseph
Moniz. The book is heavily oriented toward VB, ASP, and MTS, so some iSeries
purists may find themselves scoffing at the first few chapters -- where much
time is spent discussing the setup of a server farm. But if you hang in
there, you'll find a lot of useful concepts being explained.

Regards,

John Taylor


----- Original Message -----
From: "Joe Pluta" <joepluta@PlutaBrothers.com>
To: <midrange-l@midrange.com>
Sent: Tuesday, November 26, 2002 8:17 AM
Subject: RE: Application design


< BIG SNIP >
>
> This level of abstraction allows the application programmer to concentrate
> on the business, while the database programmer can use whatever tools best
> suit their purpose.  This also, by the way, allows a level of platform
> independence above and beyond that of SQL, which is notorious for
> inconsistencies among platforms.  With this architecture, you can add new
> non-homgenous databases by simply modifying the tier 3 attribute reporter
> and writing a new tier 4 data deployment module.  The business logic won't
> change at all.
>
> Joe
>