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Adam Bosworth article "Lessons Learned from the Web"
- To: Xanadu List <xanadu@xxxxxxxxxx>, Udanax List <udanax@xxxxxxxxxx>, Ted Nelson <ted@xxxxxxxxxx>, Andrew Pam <xanni@xxxxxxxxxxxxxxxxx>
- Subject: Adam Bosworth article "Lessons Learned from the Web"
- From: Joseph Osako <scholr1@xxxxxxxxxxx>
- Date: Sat, 19 Nov 2005 12:15:29 -0800
http://acmqueue.com/modules.php?name=Content&pa=showpage&pid=337&page=1
While he is primarily discussing conventional relational databases, I
think that he makes several points which are relevant to the Xanadu
Project as well. OTOH, some of the points also highlight important
differences between Xanadu and conventional 'data management', and
several of his criticisms of XML are in line with Xanalogical concepts,
especially in regard to link metadata (self-describing links, 'time to
live' markers, etc.)
His first 'lesson' (that text data formats are both more accessible and
more scalable than binary data formats) is already a well-known
principle among Unix programmers: outside of large database systems,
binary data formats (as opposed to executables) are almost unknown in
Unix, and for good reason. Note that human readability and editability
is a key part of this: HTML works because anyone with a text editor and
a little knowledge of the markup language can create a new web page;
similarly, the fact that HTTP addresses are plain text and easily
readable (at least for top-level addresses) has considerable impact on
the accessibility of the web - to the extent that tools for shortening
addresses, such as Snip URL (http://www.snurl.com), are quite popular as
a way of making complex addresses more accessible. The implications of
this for Xanadu are problematic, especially when taken in conjunction
with lessons 6 and 7: because to is so fine-grained, Xanadu could not
leverage these advantages even if a text format were used instead of a
binary one. Given how Xanadu addresses work, reading a link would be a
tedious exercise (how much useful information could a non-programmer get
of out a tumbler address and a span of bytes?) and hand-editing out
would be positively dangerous. Fine-grained chunking also presents
scaling problems for distributed systems, and increases the coupling,
both of which make the system both harder to use and more brittle. These
are serious problems that are inherent in the Xanadu concept - without
the ability to link to arbitrary data, it simply isn't Xanadu.
The point about staleness is an interesting one, with both positive and
negative implications for Xanadu. The fact that Xanadu data is stored
permanently, with only the data views getting changed, Xanadu should
have no problem with this; however, the fine-grained nature of Xanadu
links again becomes a concern, as updating local caches (something that
is supposed to be transparent in Xanadu, invisible to the user and
automatically balanced) for impermanent data would require considerable
overhead for consistency checking - something that the Web simply
ignores. By requiring viewer updates to be done semi-manually, and
requiring the data sources to have a custom-built solution for 'server'
updates, it forces attention to the issue - which far from being a
limitation, is a benefit, since (as Bosworth points out) no
one-size-fits-all solution could cover every case.
Lesson five, however, is very encouraging: it vindicates the basic
concept of hypertext, that non-linear presentation is not only possible
but natural once the technology to support it exists. While the web only
hints at the potential of a truly powerful hypertext system, it does
show that Xanadu's overall direction is the right one.
Not surprisingly, some of his criticisms of both XML and relational
databases do apply to Xanadu as well, but hardly all of them: if there
is one thing Xanadu documents are not, it's monolithic, and ordering is
of no consequence in Xanadu either. Still, his arguments do raise issues
that any future hypertext system - Xanalogical or otherwise - will have
to consider.