The original hypertext system and Wikipedia

Jakob Voss

The original hypertext
system and Wikipedia
We were promised Xanadu

draft slides for discussion

presented at
Fachhochschule Hannover
June, 14th 2010

Agenda
● Wikipedia
● WWW
● Xanadu
● Comparision
● Discussion

Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010

“Imagine a world in which every single
person on the planet is given free access
to the sum of all human knowledge.
That's what we're doing.”
Jimbo Wales in: Robin Miller:
Wikimedia Founder Jimmy Wales
Responds. Slashdot (2004-07-28)


Wikipedia
● Wiki-based open content encyclopaedia
● Quick editing
● Versioning
● Hypertext (pages, links, discussion pages...)
● Open Content license (CC-BY-SA)
● Founded 2001 (by accident!)
● More than 200 language editions,
10 of them with > 500.000 articles


Wikimedia
● Infrastructure
● donations and volunteers
● Wikimedia foundation and local chapters
(among them Wikimedia Germany)
● MediaWiki software
● Largest general reference work(s)
● Other Wikimedia projects
● Commons, Wikiquote, Wikisource …
● Projects only partly connected

Some more Wikipedia features
● Redirects and disambiguation
● Media inclusion via Wikimedia Commons
● Templates (Infoboxes…)
● Categories (Thesaurus)
● Interwiki links (mono-directional)
● Extracted data (DBPedia, Personsearch…)
● ...


Wikipedia revision history
http://en.wikipedia.org/w/index.php?title=Gdańsk&action=history

http://en.wikipedia.org/w/index.php?title=Gdańsk&oldid=221829087 (“Permalink“)

Internet Archive snapshots
http://web.archive.org/web/*/http://en.wikipedia.org/wiki/Gdańsk

http://web.archive.org/web/20080626090544/http://en.wikipedia.org/wiki/Gdańsk

WWW
Bild: captsolo@flickr

Tim Berners-Lee Information Management: A Proposal (1989)


World Wide Web
● invented in 1989 by Berners-Lee
to connect distributed databases
● limited to a mono-directed graph, no history
● original concepts reintroduced: collaboration
(“Web 2.0”), data integration (“Semantic Web”)


Hyperlinks
ted.hyperland.com

Ted Nelson

A File Structure for the Complex, the
Changing and the Indeterminate (1965)


“HTML is precisely what we were trying to
PREVENT – ever-breaking links, links
going outward only, quotes you can't
follow to their origins, no version
management, no rights management.”
Ted Nelson's Computer Paradigm,
Expressed as One-Liners (1999)


“Xanadu, a global hypertext publishing
system, is the longest-running vaporware
story in the history of the computer
industry. It has been in development for
more than 30 years.”
Gary Wolf: The Curse of Xanadu.
Wired Issue 3.06 (1995)


Concepts of Xanadu
● Deep links to document fragments
● Transclusion
● Versioning
● Docuverse (parallel texts)
● Strechtext (levels of detail)
● Rights management


Some properties of Xanadu
(4) Every user can search, retrieve, create and store documents.
(5) Every document can consist of any number of parts each of
which may be of any data type.
(6) Every document can contain links of any type including virtual
copies ("transclusions") to any other document in the system
accessible to its owner.
(7) Links are visible and can be followed from all endpoints.
(8) Permission to link to a document is explicitly granted by the
act of publication.
Xanadu FAQ (2002-04-12)
http://xanadu.com.au/general/faq.html#2


Some properties of Xanadu
Wikipedia
(4) Open editing ✓ partly (on-topic only)
(5) Compound ✗ very limited
documents
(6) Transclusion ✗ very limited
(7) Bidirectional links ✓ yes (inside one wiki)
(8) Reuse and linking ✓ yes
allowed


Differences
Wikipedia Xanadu
● Open content only ● Any content
● Nobody is paid ● Micropayment
● Reuse and mixing ● Reuse and mixing
encouraged but easy and tracked
difficult to track


Common properties
● Both are “closed systems”
● In Wikipedia backlinks, version history etc. do only
work inside a Wiki (not even between languages)
References to external resources are plain text only
● In Xanadu there is no “outside of the system”
● Both support mixing and changing of content
● Wikipedia solves the rights (but does not track all)
● Xanadu is based on mixing and linking of content


How can we do better?
We were promised Xanadu!


Limitations of the WWW
● Structured data ✗
● Collaboration ✗
● Backlinks ✗
● Changes ✗
● Split & Merge ✗


Limitations of the WWW
● Structured data ✓ Semantic Web
● Collaboration ✓? “Web 2.0”
● Backlinks ✗
● Changes ✗
● Split & Merge ✗ “Mashups”, “Copy & Paste”


Limitation: Backlinks
● How do you easily get the resources
that link to a given resource?
● Possible solutions
● HTTP Referrer ✗
● Notify link targets (Pinkback etc.)
● Harvest links (crawler)
● Open Questions
● Not integrated into basic Web infrastructure
● No open link databases to query!

Limitation: Changes
● How do you track changes
in documents on the Web?
● General solution
● Versioning and Diff
● Practical solution
● Adding history to the Web
● Open questions
● Which standard?
● How to diff specific file types (see: split & merge)

Adding history to the Web
● URL identifies the current
version of a Web resource
● Some create new URLs for each new version
● Old versions may also be available elsewhere


Adding history to the Web
● Memento Web Project (work in progress!)
● Additional HTTP-Header
● Typical requests
● “get the resource as it was at time X”
● “get the list of changes between X and Y”
● Related techniques
● Feeds of changes (ATOM, RSS) and OAI-PMH


Limitation: Split & Merge
● How to track merge and split on the Web?
● Problems
● Compound documents and document parts
● Clone & Merge instead of Copy & Paste
● Existing standards (Xpointer etc.) failed
● Existing solutions
● Distributed Version control systems (git, hg, bzr…)
● OAI-ORE (Object Reuse and Exchange)


Deep links in Xanadu
“An identifier for any portion/span of text (of
whatever version) can be constructed. This is in
fact the main innovation of Xanadu.”


time

version 1 text A text B

change merge
version 2 text C
change change
change

version 3 text D text E

change change

version 4 text F

change merge
version 5 text G


Types of changes

text A
text C
parallel change change
change
text
branch

text B text D text E
parallel
text


“All human beings are born free and equal in dignity and rights.
They are endowed with reason and conscience and should act
towards one another in a spirit of brotherhood.”
extract

„All human beings are born free and equal in dignity and rights.“

translate extract (sense changed)

„Alle Menschen sind frei und „All human beings are equal.”
gleich an Würde und
Rechten geboren.“


Types of changes (to discuss)
● Some practical examples
● Simple extract (quote)
● Modfied extract (thumbnail, abstract … )
● Translation, review
● Some general types
● branch (sth. “new”)
– Split (to branches that may be joined again)
● modify (expand, remove, same document)
● merge/combine (transclusion, aggregation)
– Insert into an aggregation


The original hypertext system and Wikipedia

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