xuHandout-D1y
=== 13.01.03
XANADU®-- THE FUNDAMENTAL ALTERNATIVE
Widely ridiculed and misunderstood.
Repeatedly prototyped and shot down politically.
Still valid, and with powers most people don’t imagine.
(BASIC CONCEPTS
Edit Decision List (EDL)—Hollywood origin of term
Xanalinks, individually published
Overlay Decision List (ODL)
Beam presentation
=== === ===
XANADU-- the second kind of electronic document to be invented.
(Engelbart’s were the first kind of electronic document, PARC’s the third.)
XANADU: VERY SIMPLE, HARD TO SUMMARIZE, HARD TO EXPLAIN
(it’s a sweeping paradigm, not just one idea)--
XANADU: DEEP ELECTRONIC DOCUMENTS
• side-by-side intercomparison
• flying pages and pieces in many possible structures
• visible side-by-side connections
• connection of content to origins
• unbreaking links to stabilized content
• remix with overlays
• quotations connected to their sources
• frictionless re-use of copyrighted material
XANADU: A PUBLISHING SYSTEM
• incremental publishing of versions maintains all connections
• flying comments, links may be published by anyone
but do not clutter the original
XANADU: A WORKFLOW SYSTEM
A workflow system from flying notes to finished documents
• but built for eternal revision if necessary
• content management
• version management
• side-by-side intercomparison of any two versions, showing what parts are the same
XANADU— MAKING POSSIBLE DIFFERENT STRUCTURES OF DOCUMENT, NEW DOCUMENT VISUALS
• (BEAMS THAT CAN BE TURNED ON AND OFF)
• Sworfing among views
• LADDER MODEL OF DOCUMENTS.
Ladderlike structure of parallel pages: xanadocs may be structured like ladders or cargo nets, with parallel pages connected by visible links and transclusions.
• TRANSCLUSION AS OUTLINING BRIDGE.
Corresponding pages or documents may be connected by transclusions; the same heading transcluded between them can provide a pathway between corresponding sections within the same document, or different versions of a document—for instance, the “Executive Summary” and the “Detailed Manual.”
• LINK AS STRUCTURING BRIDGE.
Xanalinks may be used as outlining bridges where the same content cannot be transcluded, for example between translations.
• Different approach to document size (e.g. for encyclopedia)
• Multiple organizations of same content, using alternative linkings
=== === === THE 1960 XANADU PAYMENT MODEL
• Content purchased by individuals per byte
• Therefore quotability smooth, don’t have to purchase whole document
• Could still find use, e.g. for comicbook panels, academic presses
(Various other models planned by others in Autodesk days—it would have been a fight)
=== === === TRANSCLUSION IN ITS VARIETY
Many people use the term “transclusion” for re-use of content by reference. (Wikipedia is based on a kind of transclusion mechanism: go to Wikipedia and search for “Wikipedia:transclusion”)
XANADU TRANSCLUSION: Only Xanadu transclusion seems to be designed for side-by-side comparison and structuring--
• Side-by-side comparison: identical transcluded portions may be seen side by side.
• Side-by-side structuring: transclusions can be used as a bridge in structuring a document.
=== TRANSCLUSION OPERATION INSTEAD OF COPYING:
XANADU DOES NOT HAVE A “COPY” OPERATION, which obliterates the origin. Instead we transclude, maintaining the origin.
=== === === XANADU AS CONTENT MANAGEMENT SYSTEM
If an organization can share a pool of stored content, every transcluded use of that content can be followed. This can make it much easier to make corresponding changes across a flight of documents.
Content ownership versus Structure ownership
• STRUCTURE ISINTRINSICALLY COPIABLE
• CONTENT MAY BE CONTROLLED AND SOLD,
since it can be controlled by the delivery source.
This provides a mechanism for fine-grain document commerce.
=== === === XANADU AS VERSION MANAGEMENT SYSTEM
Xanadu Hypertime Microversioning (a separate mechanism for going back and forth between EDLs).
• User with permission may step to any microversion.
• SIDEWAYS BRANCHING. User may go to a specific version and make a different modification that branches differently, going ‘sideways’ from the specific version without disturbing the existing sequence over versions. It is possible to transclude from one microversion sideways to another.
=== LOGIC OF XANADU DOCUMENT BOUNDARIES
Xanadu Boundary Logic—how documents may find each other, combine and open together
• TRANSCLUSION BETWEEN TWO XANADOCS: Two or more documents brought in together are like one document
•• Transclusions are visible from either side (by EDL comparison)
• LINKS BETWEEN TWO ARBITRARY XANADOCS: may be followed only from the document containing the xanalink, but may be SEEN when both are co-present
• BINDING XANADOCS TOGETHER
•• A binder xanalink from A to B makes the connection two-way—it tells the system to show incoming links from B to A. This means that document B can be seen from A.
=== === ===
=== === ===
=== === ===
THE FOLLOWING ARE ANSWERS TO THE TEST QUESTIONS, posted elsewhere.
How are conventional documents (.txt, .doc, .pdf, .teX) different from xanadocs?
APPEARANCE—paper simulation; necessarily rectangular
LINKING IN HTML—only one-way blind jumps
INTERNAL STRUCTURE
• Their content is included in the document file, with history lost
• markup is scrambled with content
What are some advantages of xanadocs?
LINKING—any types of connection
TRANSCLUSION—identitities of content viewable side by side between pages and documents (Xanadu transclusion is different from other transclusion)
ANNOTATION—possible by anyone (visible from commentator
WYSIWYNC—any type of view
How are xanadocs different from conventional documents?
INTERNAL STRUCTURE OF THE DISTRIBUTED FILE
Content is not included in the file, but brought in according to a list of content pointers (Edit Decision List, or EDL)
Links and formatting (xanalinks) are not included in the file, but brought separately available, and brought in from a list of Xanalinks (Overlay Decision List or ODL).
THIS IS THE NON-OPTIMIZED FORMAT, a much faster format is defined.
HOW ARE LINKS FOUND?
On the list of links (ODL or Overlay Decision List);
They may then be gotten individually.
THIS IS THE NON-OPTIMIZED FORMAT, a much faster format is defined.
HOW ARE TRANSCLUSIONS FOUND?
By comparison of the EDLs.
=== === === DIFFERENT XANADU VERSIONS
=== Xu72 (Hypertyper)
This used a simple enfilade, or editing tree, to rearrange externally stored content. Only one version could be maintained at a time.
=== Vortext design at Datapoint, proposed by Advanced Research Division
This used three “zip” files (this was before “zip” was a compression system—
• a cumulative text file (ZQ for Cumulative)
• a file of pointers giving the current sequence (ZS for sequence?)
• a file of overlay links (ZL for lnks?)
The design was considered “too radical” by
upper management. Datapoint did not survive long after.
=== Xu88 (Udanax Green)
ADDRESSES IN xu88/UDANAX GREEN. This uses a cosmically large address space (tumbler arithmetic) to maintain a potentially superhuge body of content.
A node (server) can have a number of accounts (authors) who can each have a number of documents, which can each have a number of versions. Content input by each author is appended to some particular document as its base address, but may then be re-used anywhere, subject to restrictions of privacy and sale.
VERSIONING IN xu88/UDANAX GREEN. It can maintain a huge number of documents and versions. Each is maintained as an enfilade representing a permutation; the version is enacted as a permutation matrix of tumbler spans.
=== Xanadu Purple, (basically a simplification to conventional files of xu88/Green)
ADDRESSES IN XANADU PURPLE. (What follows is a transposable system that may be moved on the net.)
• A document gets an unchanging numerical ID; titles may come and go.
• An author may have many individual documents, each represented by an EDL, but typically appends any original content to a single source document (permascroll). This is optional; content packages may also be posted.
• Xanalinks are published separately under their source document, but may be re-used by other xanadocs.
• CONTENT FROM OUTSIDE, presumably the web, must be cached with its address and time of origin, since its origin page may change. This is of course subject, unfortunately, to standard internet takedown rules.
span: