Re: The "Presentation" Layer

An interesting project regarding P2P is JXTA. It's a platform/language neutral P2P networking layer on top of a more primitive networking layer (like TCP/IP). In fact, it consists of a set of networking protocols that can be used to build P2P apps. E.g. for discovery of peers and available services within a P2P network. It also implements things like security. It is very robust and scalable (now on version 2.5 and quite mature).

Date: Fri, 18 Jul 2008 07:52:52 -0500
From: aaronbartell@xxxxxxxxx
To: web400@xxxxxxxxxxxx
Subject: Re: [WEB400] The "Presentation" Layer

Good point, I should be more careful of how I relate the architectures when
we are describing lower level details. So what would be the ramifications
of developing such a peer-to-peer in a GUI world? I guess it would be the
same issues of having persistent HTTP programming put in place where each
user had their own job, which could because a resource issue for a large
website.

Let me ask this: What exactly makes 5250 peer-to-peer vs. client/server? Is
it the "thin-ness" of the client (i.e. the terminal) ? Is it the
statefulness of the client in that it never loses connection and has a
direct line into the machine (brings back coaxial memories :-)?

And based on how that is answered, couldn't a guy create a "peer-to-peer"
with the JT400 classes as that will give you a handle to a specific
session/job on the AS400?

If a guy could make a JT400 connection from a thin client (like Flex/Flash)
to the AS400 then it could be seemingly peer-to-peer as there would be a
dedicated job. The reason I think dedicated jobs are ok in *some* instances
is because in *some* instances they work great. Just look at how successful
your 5250 programming has been to date. For most all new intranet
development a peer-to-peer/one-job-per-user would be perfectly acceptable
(because you already have that performance load on your AS400 through 5250
sessions).

Thoughts?
Aaron Bartell
http://mowyourlawn.com

On Fri, Jul 18, 2008 at 6:31 AM, john e <jacobus1968@xxxxxxxxxxx> wrote:

Aaron wrote:

What's so very interesting to me is that IBM chooses not to develop their
own Flex/Silverlight/JavaFX. Now this is most likely because of their

love

of Java, but I feel they forgot how successful they were with their
proprietary 5250 spec/implementation. Adobe/Microsoft/Sun are following

in

their footsteps 25 years later and saying it is "new".

5250/APPN which is the architecture the green screens are built upon is
completely different. The underlying architecture is not client/server, but
peer-to-peer. There is simply one program running on the host and it drives
the terminal, which is the other peer. This is completely different from
Flash etc. Flash/Silverlight is not new, indeed. It's simply client/server
but where the client code is provided by the server dynamically, eliminating
lots of deployment problems. And, of course, it has the "cool" factor, which
seems to be quite important these days.

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