Appendix:Xanadu

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How does the AT Protocol stand up to the rules of the mystical Xanadu?

A brief refresher:

Project Xanadu was the first hypertext project, founded in 1960 by Ted Nelson. Administrators of Project Xanadu declared it superior to the World Wide Web, with the mission statement: "Today's popular software simulates paper. The World Wide Web (another imitation of paper) trivialises our original hypertext model with one-way ever-breaking links and no management of version or contents.

Wired magazine published an article entitled "The Curse of Xanadu", calling Project Xanadu "the longest-running vaporware story in the history of the computer industry". The first attempt at implementation began in 1960, but it was not until 1998 that an incomplete implementation was released. A version described as "a working deliverable", OpenXanadu, was made available in 2014.

The original 17 rules of Xanadu

  1. "Every Xanadu server is uniquely and securely identified."
    TRUE: Every Personal Data Server (PDS), relay, AppView, and microservice is uniquely and securely identified by a Decentralized Identifier (DID).
  2. "Every Xanadu server can be operated independently or in a network."
    TRUE: Every PDS, relay, AppView, and microservice has the choice to operate in an isolated or semi-isolated state.
  3. "Every user is uniquely and securely identified."
    TRUE: Every user is uniquely and securely identified by a stable DID.
  4. "Every user can search, retrieve, create and store documents."
    TRUE: Every user can search records (through AppViews or microservices), retrieve records (from the repository of the creator), and create/store records (on their PDS).
  5. "Every document can consist of any number of parts each of which may be of any data type."
    TRUE: Every record can consist of arbitrary data structures encoded deterministically and interpreted with a common schema language.
  6. "Every document can contain links of any type including virtual copies ("transclusions") to any other document in the system accessible to its owner."
    TRUE: Every record can reference other records through a mutable AT-URI and/or an immutable Content Identifier (CID).
  7. "Links are visible and can be followed from all endpoints."
    CAVEAT: Links are traditionally visible from the source record to the target record, but following links in the reverse direction requires the use of a microservice that indexes such links.
  8. "Permission to link to a document is explicitly granted by the act of publication."
    TRUE: Permission to link to a record is explicitly granted by the act of publication to a PDS.
  9. "Every document can contain a royalty mechanism at any desired degree of granularity to ensure payment on any portion accessed, including virtual copies ("transclusions") of all or part of the document."
    SOON: No such mechanism exists on the AT Protocol as of writing. Possible through community efforts to standardize payments utilized alongside permissioned data.
  10. "Every document is uniquely and securely identified."
    TRUE: Every record is uniquely and securely identified by a mutable AT-URI and/or an immutable CID.
  11. "Every document can have secure access controls."
    SOON: Possible through permissioned data.
  12. "Every document can be rapidly searched, stored and retrieved without user knowledge of where it is physically stored."
    TRUE: End-users are not required to have knowledge of the AT Protocol.
  13. "Every document is automatically moved to physical storage appropriate to its frequency of access from any given location."
    CHOICE: A PDS could store records across multiple physical storage mediums, according to the frequency of operations for each record.
  14. "Every document is automatically stored redundantly to maintain availability even in case of a disaster."
    CHOICE: Any entity could take proactive backup measures for certain selections of records that they produce or consume.
  15. "Every Xanadu service provider can charge their users at any rate they choose for the storage, retrieval and publishing of documents."
    CHOICE: A PDS could charge users for storage, bandwidth, and maintenance expenses.
  16. "Every transaction is secure and auditable only by the parties to that transaction."
    SOON: Possible through permissioned data.
  17. "The Xanadu client-server communication protocol is an openly published standard. Third-party software development and integration is encouraged. "
    SOON: Possible through IETF standardization.

The score

  • Rules that the AT Protocol strictly conforms to: 1 through 6, 8, 10, and 12
  • Rules that the AT Protocol leaves as a choice for service operators: 13 through 15
  • Rules that the AT Protocol may conform to in the future: 9, 11, 16, and 17
  • Rules that the AT Protocol does not strictly conform to: 7