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I read Ted Nelson's autobiography. My impression was he had great visionary scale ideas, but couldn't describe a concrete implementation. I actively sought to understand concretely what Xanadu is and came up empty, a lot of high level words that could mean anything to different people reading them. Nothing concrete, at least that I was capable of understanding in the amount of time I was willing to invest. Nelson's research and vision predates computers and programmers as we know it today, so it makes sense that he wasn't a programmer. Tim Berners Lee was of course a programmer, and wrote in Weaving the Web, "having a working demo is table stakes."

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For an overview of the "user side" read his book "Literary Machines".

If you want to understand the technology behind it, consider that there have been two incomplete implementations: Udanax Green and Udanax Gold: https://web.archive.org/web/20090226223053/http://www.udanax... (the domain udanax.com now seems now to be used by someone else).

The first was based on a data structure called "Enfilade" (http://www.sunless-sea.net/wiki/EntTheory), which was invented by Roger Gregory (https://en.wikipedia.org/wiki/Roger_Gregory_(programmer)). Xanadu Gold was based on a data structure called "Ent", which is much more complicated and was according to http://xanadu.com/tech/ invented by K. Eric Drexler. Understand Enfilades before trying to understand Ents.

The best overview of an Ent that I could find (seems incomplete, though) is https://web.archive.org/web/20071027094309/http://www.sunles...

I don't know the autobiography, but everything I have read by Nelson tells me he had very specific implementation ideas.

With Xanadu he had very clear ideas, for example, about documents that link to each other (even down to the paragraph/word/character level) and are able to preserve their integrity even in the face of edits, and his collaborators were able to come up with quite brilliant technical solutions. Nelson had a lot of working prototypes made up throughout the years.

One crucial problem was that a Xanadu-style system was a closed system; in a distributed world, the same implementation would have had to be run by every single server. It was diametrically opposite in philosophy to what became the World Wide Web, with its "anything goes" URL scheme, and it was a very clear case of "worse is better" winning over a carefully designed, walled-garden ivory-tower kind of solution.

Of course, Xanadu was completely prescient about link integrity. There was a rather sad post on HN recently about an late-1990s book which had lots of URLs to resources, none of which worked.

Did he though? It's been many decades with little if anything to show for it, and Nelson admits to this day he's not a programmer. So it sounds like his ideas are just drawings and equations on paper. That's design, not implementation.

Apparently there's some old demo version, but...

http://xanadu.com/xuspViewer.html "Unfortunately this made it a very complicated package, eventually too tangled to improve further, and Rob had to get on to other things. "

So one volunteer (Rob) who actually made a working demo some years ago wrote spaghetti code that couldn't scale. That's as close as they can get to working software in decades? Granted the system they propose is difficult to grasp and likely math-heavy, but I don't see it as multiple-decades difficult given the progress computing has made in that time.

The more I read about Nelson and Xanadu, the more it seems like the people backing it have no desire to interact with reality. It's as if they expect their grand ideas, simply by virtue of being grand, will naturally create a viable product on their own somehow, and the "low work" of creating a viable product with a market is somehow beneath them.

I don't mean that they ever had a workable implementation. I mean that it wasn't just cloud talk. They did multiple implementations, of Xanadu itself and other components, some of which was open-sourced.

So it's a lot more than just visionary talk, and a little more than just design.

It might've been the above wired article, but some discussion of his work I vaguely remember was Nelson being bought into by I think autodesk, and Nelson basically managed the project poorly; the team would make headway in some direction over a year, then decide to do a fundamental redesign. Repeatedly. So a fully working product was never built, though some interesting components were

"...he had great visionary scale ideas, but couldn't describe a concrete implementation."

I revisit Xanadu every couple of years. For its time, its "closed" architecture seemed reasonable. How else would one implement persistent two-way links? Once you kinda grasp Xanadu, kludges like pingbacks and link liveness checkers seem ridiculous.

Alas, Ted Nelson, like myself, didn't anticipate, or was slow to fully appreciate, how DNS, HTTP, URL/URI would up-end the world. Whatever else was going on with Nelson, Xanadu, Autodesk, whatever, "the web" tsunami obliterated competing notions.

Animats' comment (below) about git (eg github) being today's closest realization of the Xanadu ideal is insightful.

"its "closed" architecture seemed reasonable. How else would one implement persistent two-way links"

That's a great example of a concrete implementation detail - unbreakable links means a central link database - that has significant implications in the shape of the vision. For example the only way I can think of to do unbreakable links but also distributed is an immutable public ledger perhaps something like a blockchain. And now we can talk about specifics like what other properties does a blockchain implementation shape? What does a database app with HTML forms and such look like? But did Nelson understand this? Can anyone cite an implementation source that goes into Nelson's analysis of this stuff?

Nelson was not a programmer. However, Mark S. Miller told me that he came up with http://e-drexler.com/d/09/00/AgoricsPapers/agoricpapers.html out of thinking about how to architect the full distributed Xanadu system. I believe Nick Szabo was heavily influenced by Miller's ideas in his first paper on smart contracts: it references Miller and mentions that Szabo did work for the company started up to commercialize those ideas (Agorics). It's not quite a coincidence that you think of blockchains.

I don't know how Xanadu was supposed to work on the inside. I do have a dim vague memory of seeing a mailing-list post many years later in response to someone seeking the earliest prior art on using content hashes for a distributed content-addressable store -- from someone in Xanadu. That's all I got in my memory. I want to say they also mentioned Merkle trees, but I may be confabulating. (I'd be surprised if Miller didn't know Merkle personally -- they both worked with Eric Drexler, and Drexler invented his ent just a few years after Merkle patented his tree.)

Robin Hanson published a paper back then with a non-Xanadu design sketch with similar goals: http://dl.acm.org/citation.cfm?id=43938 but it's paywalled. (Hanson also got involved with Xanadu for a little while.)

IPFS solves the addressability, availability and decentralized storage for this kind of thing.

> For its time, its "closed" architecture seemed reasonable.

The currently dominating platform gives the impression that "closed" has won nowadays.

This mythos of "working demos" needs to be put to rest.

At least in the form that many people consider "working demos".

Not everyone can, needs to, or wants to code. The ideas a person can express shouldn't be limited by the wood they can whittle. There are many game and ux folks who envision systems w/o having demos. They story board, animate or write Haiku.

Depends on your objectives. If you want people to actually use your stuff, they need to be able to... you know... use it...

Ideas don't take over the world, implementations of them do. Playing around with concepts is all well and good, but don't gripe when you can't demonstrate its usefulness and no one cares.

Look at the impact that Bret Victor has had by not releasing working demos. He communicates in ideas, others are free to implement them. If Bret subscribed to CoGTFO, he would be sucked into a quagmire of maintaining an instance of an idea. By not creating a functional artifact, he forces the universe to make multiple competing copies.

Some ideas need to shown, some can be told. Some people are really lousy at telling stories. Vastly more people can code than think creatively.

I disagree entirely. Execution is everything. If a given person has a vision but doesn't know how to code, they can either learn or hire someone to implement those ideas.

Yes, in interviews etc. he's struct me as an "ideas guy" who got stuck on the same idea for 30 years. You'd think in that time he could have just coded the damn thing.

Somehow, the ICO craze bypassed the working demo phase.

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