1. Jakob Voss
The original hypertext
system and Wikipedia
We were promised Xanadu
draft slides for discussion
presented at
Fachhochschule Hannover
June, 14th 2010
2. Agenda
● Wikipedia
● WWW
● Xanadu
● Comparision
● Discussion
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
3. “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)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
4. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
5. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
6. Some more Wikipedia features
● Redirects and disambiguation
● Media inclusion via Wikimedia Commons
● Templates (Infoboxes…)
● Categories (Thesaurus)
● Interwiki links (mono-directional)
● Extracted data (DBPedia, Personsearch…)
● ...
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
7. 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“)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
8. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
9. WWW
Bild: captsolo@flickr
Tim Berners-Lee Information Management: A Proposal (1989)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
10. 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”)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
11. Hyperlinks
ted.hyperland.com
Ted Nelson
A File Structure for the Complex, the
Changing and the Indeterminate (1965)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
12. “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)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
13. “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)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
14. Concepts of Xanadu
● Deep links to document fragments
● Transclusion
● Versioning
● Docuverse (parallel texts)
● Strechtext (levels of detail)
● Rights management
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
15. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
16. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
17. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
18. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
19. How can we do better?
We were promised Xanadu!
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
20. Limitations of the WWW
● Structured data ✗
● Collaboration ✗
● Backlinks ✗
● Changes ✗
● Split & Merge ✗
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
21. Limitations of the WWW
● Structured data ✓ Semantic Web
● Collaboration ✓? “Web 2.0”
● Backlinks ✗
● Changes ✗
● Split & Merge ✗ “Mashups”, “Copy & Paste”
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
22. 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!
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
23. 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)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
24. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
25. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
26. 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)
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
27. 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.”
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
28. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
29. Types of changes
text A
text C
parallel change change
change
text
branch
text B text D text E
parallel
text
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
30. “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.“
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010
31. 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
Jakob Voss: The original hypertext system and Wikipedia
draft slides for discussion. June 14th, 2010