WWW Applets: Embedding & Filters

Ellis S. Cohen (ellis@osf.org)
Wed, 21 Dec 1994 02:51:10 +0100

I was just looking over your WWW Applets material
and wanted to let you know of some work we've done at
OSF in the context of X that is relevant.

I agree with you that the overall browser framework
needs to support (at least as an option) viewers and
user accessories which are placed within the main browser.

The main issue in supporting embedding is the protocol
used for commnication between the parent and child applications --
among other things, this needs to support negotiation about
window placement, color, resources, transfers of focus,
propogation of inputs, support for dialogue windows,
and menu integration.

In the Windows world, OLE 2 supports this ability;
on the Mac, Apple will provide OpenDoc;
on X platforms, the winner is still unclear.

If you want to take a look at the way embedding needs
to be dealt with in the X environment, you might be
interested in the work done by Jan Newmarch, from the
University of Canberra, when he took his sabbatical at OSF.
Jan built an embedding protocol on top of ICE, a virtual
message protocol layered over TCP, and released as part
of X11R6. The code plus demos is available from Jan
(jan@ise.canberra.edu.au), and possibly may be available
from the contrib area of the X Consortium.

Jan will be giving a talk at the upcoming X Conference
(Jan 30-Feb 1 in Boston) about this work.


On the issue of filters -- as you note, one of the main
problems is characterizing the degradation factor
in translating from one format to another.

You might want to take a look at my article in Issue 5
of the X Resource, based on the talk I gave at the 1993
X Conference, on Describing Formats for X-based Data

It deals (among other things) with the more general problem of
characterizing the information carried in a selected part of a
document, and is a good starting place for dealing with
degradation issues as well.

-- Ellis