RE: Anyone using the *AFTER *READ Triggers in V5R1/V5R2?

> From: Booth@MartinVT.com
>
> An additional layer?  I thought that la rage de jour was 3 layers: bottom
> = data, middle =business rules. top=user interface(s)?  Is there a 4th
> layer being proposed Joe?

Yup.

Layer 1 - UI
Layer 2 - business rules
Layer 3 - business attributes (contained in objects)
Layer 4 - data deployment

While layer 2 depicts the business rules of my company (which accounts are
assets, which items are raw materials, which customers get which discounts),
my business attributes layer (layer 3) is the data that allows those
decisions to be made.  For example, one business attribute is the general
ledger account type, while another is the customer code.  These have an
abstract depiction - enumeration, say, or decimal value with x.y precision.
How they are stored in the database, on the other hand, is entirely up to
the data deployment layer.  The business rules never talks to the data
deployment layer; instead, all communication is through the business
attributes (and more appropriately, through the containing objects).  The
objects themselves then communicate with the deployment layer, which might
be SQL or might be message-based servers.

The beauty of this approach is that it can be implemented in any language,
including RPG.  While Java might lend itself a little more easily to the
interface definition, I've been playing around a little and it's actually
not too difficult to design the same sort of infrastructure with service
programs.  And once you've separated business logic from the data
deployment, it allows you to do some awesome things - like combine two
completely different databases seamlessly, or use both online and offline
storage, or mirror data to multiple formats, or provide transparent
logging - the list is endless.

Anyway, I realize it's a pretty major change in thinking.  Instead of
thinking about tables and rows and columns, you think about attributes and
entities.  And no, this is not EJB, which is really just a higher layer of
SQL abstraction, nor is it an object database.  It's a completely database
independent business entity definition layer.  There are places where the
overhead might be too much, at least today.  But the benefits - the benefits
are so immense in today's world of heterogenous networks that it may make
sense to start to look at it.

Joe