Hyperformance in the Hyperfuture

Presented at the John Moores University Multimedia Conference, Liverpool, May 1994.


Xanadu publishing is a long-standing proposal for a new literary and communication medium for all purposes--pluralist, populist on-line publishing on a vast scale. Many different Xanadu implementations are possible, and several have been attempted(1).

The ideas of Xanadu publishing include hypertext and hypermedia; open contributions and linkages publishable by anyone; and quotation from other documents without negotiation or red tape. These ideas have now been validated by the spectacular success of World Wide Web--an Internet service originally inspired by Xanadu(2). However, the two systems are in various respects different, built on different ideas of data storage, delivery, ownership and payment(3).

Xanadu publishing is principally based on selling copyrighted materials in small amounts. All material may be re-used and quoted without special arrangement, provided the re-use is virtual (by transclusion--a pointer indicates material to be virtually included), so that the material is bought from the original publisher at the time of delivery. Xanadu has its own detailed contracts and business model for fine-grained ownership, sale, royalty and storage payment.

All Xanadu links and transclusions are bivisible (visible from each end of the connection) and bifollowable (followable from each end of the connection). The design cleans up copyright and rights issues by finely-detailed business tracking and the elimination of red tape.

Client Programs and the Purchase Model

The Xanadu usage model assumes a reader buying fragments from many different publishers on a rapid-fire basis(4).

Many front-end client programs are possible for this, in many variegated styles. These can vary from simple, "vanilla" windowing to colorful and even baroque viewing systems. We encourage other software developers to create client programs in their own styles for presentation and exploration of this new medium.

In addition, we intend to permit Xanadu use from the popular Mosaic, formatting Xanadu output into Mosaic's HTML on the fly, even though this format represents a different model of the world from ours.

Needed: A High Performance Client

Thus there needs to be a high-performance client language, which we are calling Hyperformance(TM). It is still under design, and our principal concerns at the moment are with getting servers up, not with these later embellishments, but it is time to start thinking about them. What structures, what synchronizations, what pieces to connect in new non-sequential ways, must be specified in the virtual document?

So I would like to say a few words on the ideal, high-performance Xanadu client front end. Now that we have a high-speed network (the Internet on a good day), what will top performance look like?

Consider the 3D workstations, especially those of Silicon Graphics, and how they offer top-speed zooming, rotation and 3D roving. Consider also the high-performance software specs of some of the newer programs, especially "Live Picture," a high-performance competitor for Photoshop now about to appear on the market. Live Picture allows high-speed panning and zooming where Photoshop was glacially slow. But it should also be noted that Live Picture is said to require a Macintosh with 64 megabytes of RAM, and 128 megabytes are recommended. So software comes with a hardware price.

Nevertheless, these levels of performance are what the world is moving toward. So what will high-performance Xanadu look like?

Xanadu server performance will look the same regardless of speed. So it is Xanadu client performance that will be able to vary in its appearance.

What It Should Do

High performance views are those which involve interactive zooming and panning, interactive animation, video (possibly video in several windows), video with alpha channel (permitting moving figures to be superimposed, as allowed by MacroMedia Director); 3-dimensional movement; the wrapping of pictures or "textures" onto surfaces in real time. As well as:
Pan, scroll and zoom. Text and graphics should be able to pan, scroll and zoom at high speed.
Reversibility of operations. Xanadu connections are bidirectional and bifollowable, and correspondingly, all movements by the user through the docuverse should be reversible. Supporting reversible operations at high speed is highly desirable.
Appropriate compressions. For transmission of pictures and video, compression is important; some compressions, such as MPEG, do not map well to the Xanadu model of purchasing arbitrary sections. We are particularly interested in other forms of compression, especially fractal, that will improve performance in the client.
Animation in real time (rather than received as canned video or digital frames) is a key capability that the high performance client should have. Not only is this desirable to meet varied user needs, but it also saves on transmission time and precious bandwidth.
Fast simulations are important for similar reasons.
Vamping. In musical theater, the pianist is often given the instruction "Vamp till ready;" this means that the music should plausibly continue until the performers arrive onstage. Corresponding vamping methods must provide fulfilling animations and screen events until materials arrive over the network. So these too must be specifiable in the high-performance client. (Note that similar techniques are available in such environments as Director.)

Benefits of high screen performance. There has always been a tradeoff between screen area and resolution and fast performance. The more performance, the bigger the screen will seem to be.

The High-Performance Client Language

The Xanadu model of sale assumes that portions bought from a variety of documents are recomposited into new structures and objects in the client. This is very like the Edit Decision List (EDL), the final list of what is to be put together in a video production: the succession of shots and audio pieces to be assembled for the final production. But in the Xanadu model these must in principle be bought from different sources and co-presented in real time. Thus the high-performance client system must be able to composite various data sources into a seamless, high-performance data structure in real time.

The formatting and presentational specification for such high-performance works or documents must be rich. The high-performance client language must allow the definition of visible and virtual units and objects, their possible movements and mutations, actions upon them and interactions with them. (More conventional formatting, like SGML's hierarchical template formatting on the basis of similarities, will also be needed--but for objects composited on the fly from different sources.)

Unfortunately we cannot use the existing "standard" tools, such as SGML and HTML, because they are inside-out from the Xanadu model of transclusion. Recommended Xanadu data structures are optimized for fragmentary re-use and re-embedding of all materials in any new contexts, in any possible structures. Thus the materials do not have internal markers, as does HTML, and so the Xanadu internals are inside-out from those of World Wide Web and Mosaic.

Wrap Up

Xanadu hot front ends will need a specification system, or language, that will be of a generally new kind, although it will borrow from many sources. It will have to deal with new arbitrary data composites having many owners, and very different contexts of origin, and they will have to dance, zoom and array themselves as if they had been carefully preformatted for the purpose.


  1. Theodor Holm Nelson, Literary Machines. Mindful Press, 3020 Bridgeway #295, Sausalito CA 94965.
  2. Tim Berners-Lee, personal communication.
  3. T. Nelson, "Xanadu and World Wide Web," unpublished.
  4. T. Nelson, "Publishing in the Point-and-click Universe." Presented at the National Convergence Conference '94, Sydney, Australia, April 1994.

Copyright (c) 1994 Theodor Holm Nelson, Project Xanadu, 3020 Bridgeway #295, Sausalito CA 94965. Tel. 415/ 331-4422, fax 415/ 332-0136.
"Xanadu," "Hyperformance," "Point-and-Click Universe" and the Eternal-Flaming-X symbol are trademarks of Project Xanadu. "Live Picture" is a trademark of HSC. "Photoshop" is a trademark of Aldus. "Macintosh" is a trademark of Apple. "Director" is a trademark of Macromedia.