Project Xanadu

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Xanadu is a hypertext project founded in 1960 by Ted Nelson ; The project, named after the legendary town of Xanadu , was intended to create the Docuverse , a universal library with countless networked documents.

Xanadu's hypertext concept is comparatively complex; For example, a transclusion mechanism is provided with which parts from other objects can be seamlessly integrated into a document. In addition, a billing model was always planned in Xanadu , similar to the newer approaches of micropayments .


Like the World Wide Web , Xanadu was intended as a decentralized storage system for documents. Every document in Nelson's hypertext room should have an absolutely unique address (regardless of where it is stored). Even individual characters within the document should be addressable directly from elsewhere. Nelson thought of documents as indelible entries in a global database. The idea was that a new version could be published, but the old version of the same document remained available and differences between two versions could easily be made visible. Documents that belong together should be displayed in parallel windows, so-called transpointing windows , including the links between them.


References should be bidirectional; if you looked at a page in Xanadu, you should also see which other pages referred to that page. Instead of the usual “copy & paste”, the simple copying of content, the addresses of the content should be pasted at the point where they are used. So if you z. If, for example, a book is quoted, one would simply insert the address (i.e. the globally unique number of the book and the number of characters to be quoted) in the appropriate place, not the quotation text itself (so-called transclusion). The client (the Xanadu equivalent of the web browser) would then paste the appropriate data in the right place.

Advantages and disadvantages

Quotations automatically remain up-to-date if this is desired, their authenticity can be guaranteed, the context of a quotation can be requested immediately, and authors can be remunerated in the background without great effort. Nelson was already looking for solutions to the problem of remuneration in the digital age when hardly anyone was even aware of its existence.

Instead of laboriously pursuing every violation of rights , documents in Xanadu should be so cheap that you ignored their payment. Fractions of cents should be paid for the exploitation of one document within another, and the system of direct addressing of content instead of copying it would mean that such exploitations would remain detectable unless the system was deliberately bypassed. "I would like to live in a world where there is no copyright, but that's not how things are," says Nelson - and calls his alternative model transcopyright . It is essential to be able to transfer small amounts between users economically.


Xanadu failed because of its complexity. The system was never completed; to date only prototypes exist. Nelson had studied philosophy at Harvard University and was not technically savvy enough to go it alone or to help others implement it.

In 1988 Autodesk took over 80% of XOC (Xanadu Operating Company), where Ted Nelson worked on Xanadu until 1992. The project was then continued at Keio University in Japan until 1998 . As a basis, Ted Nelson developed the ZigZag data structure there . In 1999 it was decided to release the source code under the name Udanax. The software programmed in a Smalltalk dialect was partially ported to Java by David Jones in the Abora project . The current development version of Xanadu (2009) is administered by Andrew David Pam, who joined the project as a student at Keio University.

In 1988 Roger Gregory was obliged to complete the source code for xu88 and to deliver the system. Since several programmers had threatened to quit because of Gregory's temper, he was removed from the line. What followed was a redesign of the entire program.


Nelson's conceptual ideas for Xanadu influenced Tim Berners-Lee in the development of the World Wide Web as well as Ward Cunningham in his wiki concept. All implementations of the hypertext concept that are widespread today are functional subsets of Nelson's Xanadu .

See also


  • Ted Nelson: Literary Machines . Mindful Press, Sausalito, 1981-1993 (last edition: 93.1). ISBN 0-89347-062-7 .
  • Gary Wolf: The Curse of Xanadu . In: Wired . Issue 3.06, June 1995 (see also the public replies to the article)
  • Belinda Barnet: The Magical Place of Literary Memory ™: Xanadu . In: Screening the Past . Issue 18, July 2005
  • Georg Jünger: Xanadu - A knowledge and information system . In: taz . from 17./18. April 2003
  • Ted Nelson: The unfinished revolution and Xanadu. In: ACM Computing Surveys. Volume 31, Number 4, December 1999 doi : 10.1145 / 345966.346039
  • Xanadu Operating Company a Subsidiary of Autodesk, Inc. (Ed.): Xanadu / Server "Network-Based Software for Hypermedia Information Management" . Palo Alto 1991 ( ).

Web links

Individual evidence

  1. Welcome to Retrieved March 29, 2020 .
  2. Xanadu Secrets Become Udanax open source
  3. ^ Abora Hypermedia Project
  4. ^ Ted Nelson: Xanadu History Cue Cards . September 30, 2019, p. 4 ( [accessed May 16, 2020]).
  5. sourcedoc: NetHistoryReply-D6. Retrieved May 29, 2020 .