[self-interest] Re: remote GUI

Stefan Matthias Aust sma at 3plus4.de
Fri Feb 25 20:02:37 UTC 2000

At 19:26 23.02.00 -0300, Jecel Assumpcao Jr. wrote:

>I should have been more specific about what I want to do: basically the
>idea is to have a shared space on the internet similar to Kansas
>(infinite scrollable space) where the users can draw and "chat". 

This is actually exactly the same type of application I wanted to create
recently.  We (that is www.baltic-online.de) stopped development when we
noticed that our very generic approach was too slow.

I started with the assumption, that if X would be fast enough, then a
specially written light-weight protocol similar to X could be fast enough
to support a few (up to 10) clients over ISDN (which was our assumed
minimum).  I did this in Java and it worked very well with the exception
that cursor movements where very sluggish and because of a high lag time,
it was remotely nearly unusable.

We're now using a different approach that uses local UIs with only shared
models located in a central object database.

But interestinly, drawing and chatting, actually a collaborate whiteboard
was exactly our goal, too.

>This is easy to program in Self (it is almost done already, after all :-) and
>would work fine on a high speed LAN with people using X Windows. But I see
>that it is too ambitious to try that over a 33kbps modem.

Something that is faster than X is SLIM, the protocol used by Sun to
connect SunRay1 terminals to a central server.  There's a paper available
online about that protocol but I didn't find an exact specifiction how to
implement that protocol.  They say however, it's a very simple protocol
consisting of only 5 commands which are centered around bitmap copy.   The
paper tries to prove that SLIM is not slower than X, ofen faster and better
for multi-media applications like playing movies.

At work, we've only SunRays, so I can say that it works quite well for
typical business stuff like doing accounting or development.  (It slows
down Squeak, though, but this might be because Squeak is already slower on
X than on Windows)

Stefan Matthias Aust  //  Bevor wir fallen, fallen wir lieber auf.

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