Many years ago, in the 90's, I read a commentary at Dr. Dobb's Journal about somebody connecting using X11 using a 19,200 baud connection, and he was surprised by the speed and quality of the interaction. That really intrigued me.

That's why I'm saying that we should look more into this. I'm not so sure scalability is that bad. We actually need some hard numbers.

-----Original Message-----
From: java400-l-bounces@xxxxxxxxxxxx [mailto:java400-l-bounces@xxxxxxxxxxxx] On Behalf Of john e
Sent: Wednesday, February 06, 2008 10:53 AM
To: Java Programming on and around the iSeries / AS400
Subject: RE: Create Graphical interface

Could you please elaborate a bit on the "it is not scalable because it
is not scalable"?

I'm no expert on this. But i know it's "old" technology, and it is quite a primitive library of basic windowing functionality. The reason it is not scalable is because, for example, individual lines (primitive draw operations) are sent to the X Server (which is the program running on the PC which displays the GUI). Also, a lot of signals are sent back to the host, i.e. mouse movements and keystrokes. If you have only a couple of programs doing this it will not be a problem. But if you have hundreds of programs running at the same time and pushing individual lines to hundreds X Servers and these X servers communicate each mousemovement back to the host then this will have a big impact on overall performance. For sure it will not scale as well as 5250. In general, the interface between the client (running on the host) and the server (running on the client) is very fine grained and works ok if both are on the same machine.

Date: Wed, 6 Feb 2008 16:12:01 +0100
From: thunderaxiom@xxxxxxxxx
To: java400-l@xxxxxxxxxxxx
Subject: Re: Create Graphical interface

john e skrev den 06-02-2008 14:36:
X-Windows works over a network, but it is not scalable to hundreds of users because of technical reasons (it's architecture is not scalable). Also, unix is not like the as/400, and having one program (job/process) running for each interactive user is not a good idea in a unix environment. For unix type servers a client/server approach is best for scalability. And X-Windows is difficult to program for because the underlying base libraries are quite old (25 years).

Could you please elaborate a bit on the "it is not scalable because it
is not scalable"? Also I do not understand the rest of your arguments.
So IMHO X-Windows is only useful on the as/400 (PASE) if you have to run an existing unix utility or program which happens to use X-Windows.

Which we most likely do namely the JVM. I will try one of these days to
see if Swing is available.

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