Re: Thinking out loud about a new RPG web framework

Ahh, the joys of NEP-MRT's... Remember NEP-NOP's ?

Tom

-----Original Message-----
From: web400-bounces@xxxxxxxxxxxx [mailto:web400-bounces@xxxxxxxxxxxx] On
Behalf Of Joe Pluta
Sent: Thursday, June 05, 2008 3:15 PM
To: Web Enabling the AS400 / iSeries
Subject: Re: [WEB400] Thinking out loud about a new RPG web framework

Aaron Bartell wrote:

Have a "mother router" program that sits under Apache and all it does is
receives in HTTP requests from the browser and based on a hidden form

value

(or cookie storing a session ID) it would appropriately "write" that

request

to a keyed data queue where a program is waiting for that specific

session

key. Upon receiving the data queue entry, the business logic program
processes the contents of the HTTP post by evaluating the action that was
taken (just like how green screen programming checks for the function

key).

It then determines what to respond with and goes back into a wait state

on
a

data queue "read" (just like waiting on EXFMT). The benefit in this case

is

that all global variables, open data paths, and SQL cursors were able to
remain open and stateful as it relates to that specific users

interactions.

The data queue layer is basically acting as the replacement mechanism for
EXFMT.

The issue I had previously is that each web browsing user had their own

job

on the iSeries which could potentially become burdensome for a public
website with thousands of users coming in.

I'm not going to go too deep into this today, but I am a little hazy on
some specific issues. Let's say you have 100 users doing order entry.
They're all calling the same program. Is there only a single instance
of this program? Or is there one per user? If it's the former, then
that program will have to restore state based on the session ID for
every request. This is what we had back in the days of NEP-MRT CCP, and
it's *not* a trivial task, especially as the programs grow.

If, on the other hand, there is one job per session, then why bother
with the mother router? In fact, let each HTTP session have its own job
and now we're back to my architecture. In fact, with servlets, we just
use the toolbox to create a connectin, and the job we use is the
QZRCSRVS job.

There is the issue of scalability for large sites, but the majority of
those sites can probably use a non-persistent application such as a
catalog right up until the time when they need to actually do an order -
which is when they need to log in and fire up the RPG program, which is
when you would establish a support job.

Joe
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