The ZigZag structure...is extremely simple but has remarkable properties.
GZigZag, Gzz, fenfire, ...
On the downside, patent problems have caused open source implementations of these same ideas to be politely shutdown.
It's interesting to trace from GZigZag to Gzz to fenfire, and I've heard that's still not the entire story.
a cosmology for a different computer universe :)
Technically, ZigZag is a database and visualization/user-interface system for a subset of general graphs - the restriction is that a node may have only one incoming and one outgoing edge with a given edge label. So structures are organized as lists/strings of nodes, which makes it easier to visualize than general graphs, that can have any number of edges with a given label incoming/outgoing on a node.
Nelson explained that he never succeeded as a filmmaker or businessman because "the first step to anything I ever wanted to do was Xanadu."
Xanadu was meant to be a universal library, a worldwide hypertext publishing tool, a system to resolve copyright disputes, and a meritocratic forum for discussion and debate.
He pointed out that the Web still lacks nearly every one of the advanced features he and his colleagues were trying to realize.
But something seems flawed with Nelson's vision of Xanadu/Theweb: point of the whole server reliability seems to be to charge the user for anything done to data (reading, mashing up, copying or distributing). The web as we know it today might not be as close to Xanadu's vision as we'd like it to be but at least we can swim in that ocean of data in a free and anonymous way.
Worse than that: it was kinda RIA's and MPAA's heaven. Which means that would've been a TERRIBLE world to live at, for the rest of us.
If you can find a used copy of his books 'Literary Machines' and/or 'Computer Lib', get em and read em. 'Literary Machines' describes the goals and design of Xanadu, and the philosophy/motivation for hypertext. 'Computer Lib' is about what personal computers could do for culture and society.
It amuses me that someone can loudly proclaim that most people are fools and most authority is malignant...
...and yet be a malignant, foolish authority all at the same time.
And the idea that simply putting information out there will cure scientific ignorance and produce political harmony is a fallacy that should have been stamped out fifty years ago, yet is still blissfully held on to. There's no reason to suspect people work in this way, and much evidence to show quite conclusively that they don't.
I think it's worth considering that monoculture (that is, the ubiquity portrayed by a concept like Xanadu) hinders development (in the broad sense, if not the software sense per se).
While having a single login for the web may have its perks, it also has its limits. I value being able to identify myself differently for different purposes on the web, personally. I don't like the idea of my identity for discussing politics being mixed up with my identity for job hunting.
One of the most stupid limitations is Copy & Paste: You copied the "17 rules of Xanadu" from the Xanadu FAQ but the reader has to reconstruct the connection. It is not obvious who wrote the original list (Andrew Pam at some time between 1994 and 2002) and whether you modified something or not (you modifed the numbering schema). I would prefer a Wiki-like diff with your article at one side and the source at the other and then browse the version history of the FAQ to see when which sections were added.
Every Xanadu server is uniquely and securely identified.
Every Xanadu server can be operated independently or in a network.
Every user is uniquely and securely identified.
Every user can search, retrieve, create and store documents.
Every document can consist of any number of parts each of which may be of any data type.
Every document can contain links of any type including virtual copies ("transclusions") to any other document in the system accessible to its owner.
Links are visible and can be followed from all endpoints.
Permission to link to a document is explicitly granted by the act of publication.
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.
Every document is uniquely and securely identified.
Every document can have secure access controls.
Every document can be rapidly searched, stored and retrieved without user knowledge of where it is physically stored.
Every document is automatically moved to physical storage appropriate to its frequency of access from any given location.
Every document is automatically stored redundantly to maintain availability even in case of a disaster.
Every Xanadu service provider can charge their users at any rate they choose for the storage, retrieval and publishing of documents.
Every transaction is secure and auditable only by the parties to that transaction.
The Xanadu client-server communication protocol is an openly published standard. Third-party software development and integration is encouraged.