Path: utzoo!utgpu!watmath!clyde!att!pacbell!lll-tis!helios.ee.lbl.gov!pasteur!dent.Berkeley.EDU!davidh
From: davidh@dent.Berkeley.EDU (David S. Harrison)
Newsgroups: comp.sys.next
Subject: Re : Display PS vs NeWS
Keywords: NeWS is a superset of POSTSCRIPT!
Message-ID: <7957@pasteur.Berkeley.EDU>
Date: 3 Dec 88 02:44:57 GMT
References: <2391@ssc-vax.UUCP> <941@riddle.UUCP>
Sender: news@pasteur.Berkeley.EDU
Organization: UC Berkeley Electronics Research Lab
Lines: 35

(ed. Positive comments about NeWS;  Negative comments about X.
     Plus the following debatable statements:)
> I have a healthy respect for X11 but with the
> exception of the networking it is the same old ten (or more) year old 
> techology ... it is no REAL breakthrough...X is a toy when compared
> technically with NeWS...(you can emulate X from NeWS...the reverse is
> not possible) ...
> ... and if I want to have X do what NeWS
> does ...sigh...well then I CAN'T DO THAT. (sorry for being obnoxious...
> but consider it an education).

I have often heard these opinions stated by NeWS advocates.
Unfortunately,  they are not entirely true.  In its current
form,  NeWS *cannot* fully emulate X.  This is because the
NeWS color model *does not* support writable color tables.
Furthermore,  there are operations supported by X which
cannot be efficiently emulated under NeWS.  The prime example
is stipple filled areas.  The Postscript/NeWS display model 
does not support writing a certain pattern of bits onto the
display without changing the bits not specified in the pattern.
This can be emulated but the replacement operations are *very* 
slow.  These two features alone rule out reasonable implementations
of a wide class of color graphics editors under NeWS (including
the one I have developed under X).

Please don't misunderstand:  I see many advantages in the NeWS
model.  However,  the argument is far from one sided.  There
are several serious problems with NeWS in its current form.  X,
although low-level,  addresses many of these problems.  That
is precisely the reason why Sun has decided to produce a combined
X11/NeWS server (not just an X11 emulator above NeWS).

				David Harrison
				UC Berkeley Electronics Research Lab
				(davidh@ic.Berkely.EDU, ...!ucbvax!davidh)