RE: Green-screen versus browser

Comments in-line... 


John A. Jones, CISSP
Americas Information Security Officer
Jones Lang LaSalle, Inc.
V: +1-630-455-2787  F: +1-312-601-1782
john.jones@xxxxxxxxxx

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Reeve
Sent: Sunday, April 24, 2005 10:02 PM
To: Midrange Systems Technical Discussion
Subject: Green-screen versus browser

>>"The problem with green-screen is that the programmer is limited to a
fixed font size, a limited color palette, essentially no support for
graphics, only 132 columns (across), only 27 lines (down), and the
requirement to use a non-standard, usually non-free terminal emulation
program (Client Access, etc.), which means you can't talk directly to
many new communications devices like PDA's.<<

I have a tn5250 client on my PDA.  Many handheld scanners from Symbol,
etc. have 5250 access.  I think the line about comm devices should be
removed.  Also, an advantange of a green-screen on a PDA (or in general)
is that there's less/no temptation for developers to bloat the UI.
Also, while there are free emulators, Mocha can be had for for $250 for
a license for an entire company.  Email-based support appears to be
free.

>>"There is nothing innately good about browsers; except for Firefox,
they're bloated with generally useless features, each has its own unique
characteristics (meaning it doesn't work exactly the same as other
browsers), and many continue to be a gateway ("Gates way"?) for viruses
and spyware.<<

If you want management to take your comments seriously, remove the Gates
bashing.  I would also remove the 'bloated and generally useless' part.
I'd probably word it something like this:

There is nothing innately good about browsers.  Each has there own
characteristics and compatability issues.  Indeed, within versions of
the same browser compatability issues often exist.  Browser feature
support also varies considerably across versions and across operating
systems; what works on Windows may not work the same on an Apple or a
Linux-based system.  Web application developers that want to include
rich content but need to support more than a single version of a single
browser on a single OS generally devote additional development resources
to cross-browser and cross-platform support.  Also, browsers are a major
entry-point for spyware and along with email are major entry points for
computer viruses.  

Conversely, 5250 has none of these issues.  A 5250 emulator is available
for all major and most minor computing platforms.  Applications are
written to the 5250 data stream; compatability issues are extremely
rare.

>>"The benefit of browsers is that the programmer has much greater
control over what the user sees and how the screen works...but it takes
a lot more programming effort to deliver a browser-based application.
The basic tradeoff is balancing time-to-deliver (low for green-screen,
high for browser), function (low for green screen, high for browser),
and performance (relatively high for green-screen, relatively low for
browser).<<

The benefit of browsers is that the programmer has a wider array of
capabilities that can be delivered as part of the UI, potentially
enriching the user experience.  However, a browser-based application is
rarely more efficient as a data entry or reporting tool than a 5250
application once the user training period is over.

Both browser and 5250 solutions are host-based computing models.
Browsers require a smarter client, but with PCs displacing terminals for
5250 usage, the point is moot.  On the host side, the 5250 data stream
takes far less host CPU and RAM resource than a web page that serves
dynamic content.  Web pages are almost universally larger than 5250
screens in terms of the data being sent, so a web server will require
more bandwidth than a 5250-based server.

Typically, data entry will use less host resources when done via 5250.
Also, because a data-entry clerk can keep their hands on the keyboard
and not have to reach for a mouse, and because the communications
overhead is smaller with 5250, data entry will tend to be faster with a
5250-based session.  Both browser and 5250 solutions allow users to
submit batch work and there is no difference in batch run times since
the batch process does not use the browser/5250 data stream when
running.



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