User interfaces for low-bandwidth links, 3270 or 5250 on Unix/linux?

We have a large number of overseas sites connected over a WAN.  These links range from 8kbps to 2Mbps, >75% of worldwide sites have bandwidth < 64kbps and there are often several users sharing the link during the day.

We have a strategy for thin-client (i.e. Browser) application development, but real-time operational systems developed with a Browser interface have proved to be slow, even after considerable tuning.

Successful applications running in this environment are mainframe based, with 5250 or 3270 based interfaces.

What I think we're after is a text based interface which uses very little bandwidth (such as 5250,3270 or telnet) and can be used on low cost unix/linux platform.  Ideally linking to Java based functionality running on an application server (e.g. Weblogic).  But the interface should not be command line driven.  Rather it should support function keys, colours and possibly menus, dropdown lists etc.

Any ideas?  What are other people doing in these harsh conditions?
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sunnycoderConnect With a Mentor Commented:
Hi davidbartrum,

I do not know what people do in such harsh conditions, but I think you should be able to program a GUI for telnet ...

GUI application can run locally (just like you have locally installed browser) .... it can accept commands from the user ( in form of mouse clicks or menu selections or text ) and communicate them to the remote site using telnet ....

The user interface and the user's experiance need not be the criteria of the bandwidth usage.
The bandwidth is on actual data transferred.
A CUI or a Gui makes no differance  as the bandwidth is not governed by the client-softwares or the server-softwares size. as long as the same is not trans mitted across the network
In such cases most of the times thin clinet creats more overload on net worsk as teh user experiance has to be transmitted over the network along with the data

 to illustrate an example
     -> a web page with a javascript ot java applet or a activex on web page takes more bandwidth
        in contrast if we make a GUI front end and only the data is transferred the bandwidth usage is far less
     -> another example is a chat page using a n applet and a chat using a messenger.

If I were in a situation like that I coulds make my first step to adopt or create a communication protocol that could be text based(naturally) and that could be lightest possible.
and get a messenger like front end for it

davidbartrumAuthor Commented:
SunnyCoder's suggestion is basically "screen scraping".  The GUI sits ontop of a telnet session and depending on user activity, submits text based commands to unix over the telnet session.  The unix responses (screen) must be parsed (scraped) by the GUI and displayed to the user in an appropriate way.

A more acceptable variation to this might be for the data to be returned to the client as XML.  At least this would be easier to parse, while still being human readable for debugging and for a raw telnet user.  I'll consider this further.

For the 5250 part You should take a look at Jadvantage from BOS, which is a web based 5250 emulator with all functions like Client Access.
It runs on most Java enabled platforms, including Linux, Mac and windows.
For the low bandwith connections there are Telnet or an old Application also from BOS. It is called Advanced Server for SAA. It's a SNA server like application allowing you to transfer green screens over TCPIP links.

Kim P.
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