Re: EGL and other things

Joe wrote:

The correct architecture (which as far as I know we've all agreed on for
some 15 or 20 years now) is to use RPG to build your business logic and then
attach it to your UI using some sort of SOA attachment. Web services, data
queues, RPC, I don't care. But the business logic should be entirely UI
agnostic, and that's what EGL does for RPG. Even green screen programs
should be written so that the UI doesn't have business logic in it, right?

Joe, you mention "correct" architecture. What is "correct"? What you actually mean is that the "architecture" of the day is to have the business logic (or, the application) on the server and the UI being presented on the client, using a plethora of alternative tools and technologies. And you have plenty of them, for me a indication that this "correct" architecture is still heavily evolving. Let's see in five to ten years.

A "correct" architecture is any architecture that is robust, scalable, and.... simple. What seems to happen these days is that the wheel is invented one more time. I.e. we use a combination of HTML, CSS and Javascript to communicate with the server and present the UI. But because we want "Rich" application we push this browser based stuuf further and further and add in more and more Javascript and CSS to present these rich UI's. But... we already had these nice and very rich UI. It's called a "GUI", nothing new under the sun.

I don't believe (and history supports me) in technologies that are "dropped" on our head and require a completely new (to most RPG'ers) technology. This top-down approach never worked. All relevant technologies that become populair were grass roots developments. HTTP, HTML were years ago invented to simply present documents with "hyper text" capability. HTTP only became a "standard" and (in your words) "correct" architecture simpy because it became populair and hype. These days, if a technology isn't HTML/Javascript/Browser based it's not "modern" and should be ignored. HTTP is okay for documents and the like (for which it was intented). But for e.g. OLTP apps it's... well.... pathetic. I know, "stateless" is the way to go, that's the saying. But why? Only when you are amazon and have 100.000 hits a minute. But for day-to-day apps which run within a controlled environment (a LAN) is "stateless" the right architecture? Apparently not, because we need all kinds of frameworks ala JSF to "fake" stateful sessions. This is just one example.

I don't think the whole HTTP/HTML/CSS/Javascript is the "correct" architecture for our business apps. It works, maybe... with a lot of complexity thrown in. And what do we get back? An app running on the server, and a UI presented on a browser, or client, or terminal or whichever you name it. But is this progress?? A 5250 green screen app gives us the same, but without all the unneccesary complexity just to cope with the underlying "correct" architecure. No i'm not advocating green screen apps. It's a shame that we still program green screen and completely missed the client server development. What i mean is that the only difference between green-screen and web-based actually is that "web-based" is "Rich" and simple HTML and green-screen is not.

You said that the business logic should be UI agnostic. Yes, of course, but does this automatically mean it is bad practice to program a UI with RPG??? Of course not. SEPARATION is what is important. Separate the UI from the business logic. But the UI could be programmed in RPG, nothing "bad" about that. Only thing is.... we only have green-screen functionality from RPG. And this is historical, has NOTHING to do with "JSF" or whatever being the "correct" architecture.

Jacobus

From: joepluta@xxxxxxxxxxxxxxxxx
To: web400@xxxxxxxxxxxx
Date: Sun, 16 Dec 2007 14:42:32 -0600
Subject: [WEB400] EGL and other things

From: Aaron Bartell

those initiatives have died (i.e. EXUI opcode or something like that)

EXUI is gone at least in part because it's a bad idea. RPG is a business
language, not a UI language. It has never been a UI language. Even 5250
was a graft; it required a completely different language (DDS), special
opcodes and a powerful dedicated client machine (the 5250).

The correct architecture (which as far as I know we've all agreed on for
some 15 or 20 years now) is to use RPG to build your business logic and then
attach it to your UI using some sort of SOA attachment. Web services, data
queues, RPC, I don't care. But the business logic should be entirely UI
agnostic, and that's what EGL does for RPG. Even green screen programs
should be written so that the UI doesn't have business logic in it, right?

Given your love for RPG, can you say you have heard cool things coming
down the pipe for that language?

Yeah. Multithreading, for one. Ought to make Steve happy. I think I heard
that you will be able to pass files between procedures, which could make for
some very interesting encapsulation capabilities.

But be clear, I'm not an IBM employee. I know a lot about EGL because I am
one of a group of business partners who work closely with the EGL team. I
don't work with the compiler team the same way, so I don't know what the
specific future of RPG holds. I can tell you though what I know from
discussion with various IBM officials, and RPG and i5/OS are both still
strategic. A bunch of us just met with Marc Dupaquier, and while I'm under
NDA on the specifics of the discussions, I can guarantee you that i5/OS is
still a major part of the future.

Joe

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