On Thu, Jan 12, 2017 at 1:08 PM, Evan Harris <auctionitis@xxxxxxxxx> wrote:
Hi Nathan
<Snip>
Regarding business rules, it is best to implement them in a language
environment which has direct access to the database as opposed to language
environments which don't (i.e. Java, Ruby, PHP, Python, Perl, .Net,
Node.js, etc.). I'm surprised at the number of OO developers who argue
otherwise.
</SNIP>
I admit to writing that - just for the sake of reference. Note that I was
referring to "business rules", as opposed to the ambiguous term "business
logic". Rob cited an example of a business rule - don't ship more than you
have on hand.
What does this actually mean in practical terms ?
Given a rule like - don't ship more than you have on hand, the logic to
implement that hasn't been defined, but for the sake of discussion let's
say that it requires access to several database records and more logic than
just database joins. I'm suggesting that the logic be encapsulated into a
procedure, running in a language environment that runs in the same address
space as the DBMS, using a language that provides for record-level access.
Let's take another rule: when adding an order item, retrieve the next item
sequence number from the order header and associate it with the new item,
and update an item total. That's another example of rules which are best
implemented in a procedure that provides RLA and runs in the same address
space as the DBMS.
Such procedures could be invoked from components running in language
environments that don't run in the same address space as the DBMS. It's
such a waste of time and resources to implement those types of rules in
language environments that are designed to perform something like browser
I/O.
I may be reading it incorrectly, but it seems to say that anything but RPG
is not the best choice - or is there another language that you have not
listed that meets your criteria of a language that has direct access to the
database?
RPG would be my preference on IBM i. But what if your DBMS is Oracle or MS
SQL Server? Developers might use SQL stored procedures, which do run in the
same address space as the DBMS although my point about "direct access" is
debatable. I'm not sure if Oracle and MS SQL Server provide RLA in addition
to SQL.
By extension this means that *everything* would be "best'
implemented on an IBM i (I can't think of a meaningful application that
does not use a database at all).
I think that's stretching my assertions about the implementation of
business rules too far. But I do believe that IBM i offers unique value,
which exceeds the value propositions of every other application / database
server on the planet - and that business would do themselves a service by
migrating business applications and database workloads off other platforms
to IBM i on Power.
midrange.com
