FYI: Osmic
Jim Whitehead (ejw@ics.uci.edu)
Mon, 15 Feb 1999 11:20:56 -0800
From: Jim Whitehead <ejw@ics.uci.edu>
To: Versioning <ietf-dav-versioning@w3.org>
Date: Mon, 15 Feb 1999 11:20:56 -0800
Message-ID: <007d01be5918$4fad57c0$d115c380@galileo.ics.uci.edu>
Subject: FYI: Osmic
Ted Nelson, the researcher who coined the term "hypertext" and who worked
for many years on the Xanadu system, has recently been working on
versioning, as part of his Osmic system. The Osmic approach is much more
fine-grain than the WebDAV versioning proposal, and is more similar to
synchronous collaborative editors. For details on Osmic, including access
to the code for a running demo, go to URL:
http://www.sfc.keio.ac.jp/~ted/OSMIC/OSMICpage.html
The versioning model is described more at:
http://www.sfc.keio.ac.jp/~ted/OSMIC/osmicTime.html
IMO, one of the fundamental departure points between the Osmic work and the
WebDAV versioning work is that WebDAV provides the same versioning
facilities to all content types. Providing more fine-grain versioning
requires content type specific knowledge so you know what the basic
operators are for that content type (what does "insert" mean for a bitmap
image?). Internal knowledge about the content type is needed if the content
type has a checksum, or a complex internal structure, which prevents it from
being treated solely as a set of bytes for merge operations. In turn, the
content-type specific knowledge then makes the protocol more brittle, since
it is now dependent on the definition of the content type, and many
frequently-used content types on the Web are in constant evolution, making a
protocol based on them brittle. Of course, if you limit yourself, as Osmic
does, to ASCII text (a stable, and widely supported content type) these
problems don't appear.
- Jim