To: Steven.Hoover@edrc.cmu.edu
In-reply-to: Steven.Hoover@edrc.cmu.edu's message of Tue, 23 Aug 88 08:42:43 EDT
Subject: Questions about windowing systems: NeWS?
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   Date:    Tue, 23 Aug 88 08:42:43 EDT
   From:    Steven.Hoover@edrc.cmu.edu

   There seems to be a proliferation of graphics tools and windowing systems
   for Sun machines and I'm confused.  So please excuse my ignorance and help
   me by answering some very basic questions.  I realize that these may
   require some long uninteresting answers to the experienced SUN hackers out
   there so please mail your responses to me.  I will summarize if there is
   interest.

   1.)  Under SunOS 4.0 what are the functions of Suntools, SunView, 
	SunCGI, Xwindows and NeWs?

Well, Suntools is Sun's original window system, and SunView is the
user interface toolkit on top of it. 
The window system code lives partially in the operating system
kernel, and partially linked into the client. (A client
is a program 
that runs under the window system, and uses its services). Each
SunView client must run on the same machine whose display it is using,
and have the huge SunView libraries linked into it. The latter is not
such a problem with SunOS 4.0, which has shared libraries, but right
now, SunView program right can't be run on a remote display over the
network. This will change with the next version, SunView 2.0, which is
built on top of X11/NeWS. The toolkit will still be linked into
clients, but the graphics code will reside in the X11/NeWS server.

I've never used SunCGI, but I think it's a package that runs on top of
SunView. I guess that it will migrate to SunView 2.0.

X-Windows is a public domain network based window system devaloped by
MIT, for DEC and other companies. X10 was a earlier, simpler version,
that is now pretty much obsolete. X11 is the latest version, which is
what you have been hearing all the industry hype about. The X server is a
program that runs on the machine with the display, and contains all of
code to do graphics. X clients talk to the X server over the network
or via local interprocess communication.  The X11 interprets a set of
commands called the "X Protocol", that your client uses though a
library called "XLib". 
There is a way to add extensions to the X server (by recompiling the
server and starting another one, unless it supports dynamic linking),
and a way for clients to ask the server if it supports a particular
extension. XLib is a rather low level interface to write an
application with, so there are several user interface toolkits
available written on top of XLib that save you the trouble of dealing
with it directly, such as the X-Toolkit, Andrew, and Interviews. The
toolkits available under X are linked into window system clients --
they are not a part of the X server. 

NeWS is Sun's PostScript based network window system. It is similar to
X in that clients can use the window system over the network, but the important
difference is that NeWS, like the Emacs editor, is extensible! The
NeWS server provides a multitasking, object oriented, device
independant PostScript programming environment. NeWS clients customize
the server to their needs by sending PostScript programs and data over
the network. The toolkit is written in PostScript, and runs in the
server, instead of being completely linked into the clients. Clients
running on different remote machines can all share the same PostScript
code, which runs in the NeWS server on the machine where the mouse,
keyboard, and display is. It can respond quickly to user input
without the lag of network communication, and process input locally to
cut down on the ammount of network utilization. 


   2.)  To what extent are any of the above compatible or mutually exclusive?

   and most importantly

   3.)  If I have a Sun-3/160 running 4.0 and NeWs networked with another
	unix workstation (Specfically an IRIS 4-D system) which runs NeWs
	what functionality does this give me? 

   Thanks,

   Steve Hoover

   sph@edrc.cmu.edu

   Department of Mechanical Engineering
   Carnegie-Mellon University
   Pittsburgh, PA 15217

Well, this summer, I have been using a color Sun-4/110, a monochrome Sun-3/160,
and a color SGI IRIS 4-D, all running NeWS 1.1. I've been working on
the NeWS display driver for Unipress Emacs, building an interface to 
windows, menus, control panels (buttons, scroll bars, etc), text selection
(rubber-band highlighting of text during mouse dragging, moving text
between NeWS and Emacs, etc...). Once we got 4Sight 1.1 from SGI
(their NeWS 1.1), I 
had all that PostScript code that had been developed on the Sun up and
running very quickly! It only took one night and a big mug of Capachino to
get the Emacs display driver working, and to make pie menus run in the SGI
overlay plane, and then a week or so to smooth it out and get the
driver into shape so that it would work on any of the machines. There
are a few differences between SGI's NeWS 1.1 and Sun's, that I had to
cope with. 

The most noticible thing is that the default transformation
matrix under 
Sun NeWS is [1 0 0 1 0 0], so the width and height of a pixel is 1,
while it's [1.324 0 0 1.324 0 0] on the SGI, so the width and height
of a pixel is 0.756. PostScript is resolution independant, but there
were a few assumptions in the code about pixel size -- drawing borders
and such, and I hade to make sure the transformation matrix I was
using to place characters was lined up with the pixels so there was
the same ammount of vertical space between each line. 
I had to fix some problems with font turds -- I got tired of watching
it leave the tips of p's and q's around. 

Another problem was with the keyboard -- SGI was doing the keyboard
translation in C instead of in PostScript, so I could not tell if the
meta keys were down. The state of the shift keys were not being
encoded in the events as high level names like /Control and /Shift, but
as raw key stations. There was no way to tell if the Alt (meta) key
was pressed that I could figure out. This was a problem that they say
will be fixed in the next release. 

Also, the SGI is VERY slow at scrolling and blinking the screen, or
any task where the main CPU needs to read data out of graphics memory.
It's *VERY* fast at rendering text, though! If Emacs is run with a
4Sight NeWS server, it repaints instead of scrolling (setq
use-ins/del-line/char 0), and beeps the keyboard instead of blinking
the screen (setq visible-bell 0).