Newsgroups: comp.constraints
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!howland.reston.ans.net!news.starnet.net!wupost!uhog.mit.edu!bloom-beacon.mit.edu!crl.dec.com!crl.dec.com!pa.dec.com!heydon
From: heydon@usenet.pa.dec.com
Message-ID: <9501060214.AA14752@spieler.pa.dec.com>
Subject: The Juno-2 Constraint-Based Drawing Editor
Date: Thu, 05 Jan 95 18:14:05 -0800
X-Received: by usenet.pa.dec.com; id AA17561; Thu, 5 Jan 95 18:14:07 -0800
X-Received: by spieler.pa.dec.com; id AA14752; Thu, 5 Jan 1995 18:14:05 -0800
X-To: comp.constraints.usenet@usenet.pa.dec.com
X-Mts: smtp
Lines: 75


This is to announce the availability of the following research report
from the Digital Systems Research Center (SRC):

"The Juno-2 Constraint-Based Drawing Editor"
Allan Heydon and Greg Nelson
Report #131a, December, 1994, 19 pages.		

The report is available in hardcopy, on the web, and by anonymous FTP.
The World Wide Web URL for SRC's research reports is:

  http://www.research.digital.com/SRC/publications/src-rr.html

The research report is also available via anonymous FTP on the
machine "gatekeeper.pa.dec.com" as the file:

  pub/DEC/SRC/research-reports/SRC-131a.ps.Z

(An accompanying video (#131b) is in preparation).

I've attached the abstract for the report, as well as a perspective
written by our colleague Lyle Ramshaw. Unfortunately, we are unable to
make the Juno-2 application publicly available at this time. In the
future, we may make executable binaries available for a limited number
of platforms.

- Allan Heydon

--------------------------------------------------------------------
Allan Heydon                           Digital Equipment Corporation
heydon@pa.dec.com                      Systems Research Center
(415) 853-2142                         130 Lytton Avenue
(415) 853-2104 (FAX)                   Palo Alto, CA 94301
--------------------------------------------------------------------

ABSTRACT

Constraints are an important enabling technology for interactive
graphics applications. However, today's constraint-based systems are
plagued by several limitations, and constraints have yet to live up to
their potential.

Juno-2 is a constraint-based double-view drawing editor that addresses
some of these limitations. Constraints in Juno-2 are declarative, and
they can include non-linear functions and ordered pairs. Moreover, the
Juno-2 solver is not limited to acyclic constraint systems. Juno-2
also includes a powerful extension language that allows users to
define new constraints. The system demonstrates that fast constraint
solving is possible with a highly extensible, fully declarative
constraint language.

The report describes what it is like to use Juno-2, outlines the
methods that Juno-2 uses to solve constraints, and discusses its
performance.

PERSPECTIVE

Computers now handle the words in the documents that we write, and
that is good: Revising, indexing, and formatting are lots easier,
while hyperlinks have opened up shining vistas. Computers also handle
the illustrations in our documents, but the news on that front is not
so good. Producing accurate drawings is still a tedious task in many
cases, revising them later is worse, and animations are not taking off
as fast as hypertext. Even if we grant that a picture is worth a
thousand words to the reader, why is its cost to the writer more like
ten thousand?

If computers are ever to help illustrators as effectively as they help
authors, some new ideas will be required. Juno-2 is a drawing editor
that explores an intriguing collection of ideas about two-view
editing, constraint-solving, and extension languages. This brief report
gives some early indications of the strengths and weaknesses of those
ideas.

Lyle Ramshaw
