It has been suggested that this article be merged into Project Xanadu . (Discuss) Proposed since October 2023. |
The topic of this article may not meet Wikipedia's general notability guideline .(June 2010) |
In the design of the Xanadu computer system, a tumbler is an address of any range of content or link or a set of ranges or links. According to Gary Wolf in Wired , the idea of tumblers was that "the address would not only point the reader to the correct machine, it would also indicate the author of the document, the version of the document, the correct span of bytes, and the links associated with these bytes." Tumblers were created by Roger Gregory and Mark Miller. [1] [2]
They were used in the Xanadu FEBE (Front End - Back End) protocol in a manner similar to the use of URIs between web browsers and servers.
The idea behind tumblers comes from transfinite numbers. [1] A tumbler is a unique numerical address of any interesting artifact. It resembles an IP address, but is much larger and has much more detailed structure. The structure looks like this.
1. < node >.0. < user >.0. < document >.0. < element >
The leading "1." is used in order to mark the start of a new address. The individual fields of the address are divided with ".0." so that they can be arbitrarily long. Each < element > has the format "n. n. ... . n", a hierarchy of subaddresses.
The last element denotes the type of data the tumbler refers to, for example:
Address area | Tumbler Address | Comment |
---|---|---|
Node | 1.2368.792.6 | This is the computer with the number 2368.792.6 |
User | 1.2368.792.6.0.6974.383.1988.352 | This is user 6974.383.1988.352 on the above computer. |
Document | 1.2368.792.6.0.6974.383.1988.352.0.75 | The user's document number 75. |
Version | 1.2368.792.6.0.6974.383.1988.352.0.75.2 | Version 2 of the document. |
The 9287th byte of this version of the document would be 1.2368.792.6.0.6974.383.1988.352.0.75.2.0.1.9287 and the 356th link would be 0.2.356 on the end instead.
A tumbler can be issued only once and never changes. The type of structure can grow at will, so the address space is infinite.
Nelson also introduces the concepts of direction and a "span", which is a part of a document that is semantically meaningful for the document. For example, one can speak of "2 chapters back" or "300 bytes forward".
The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It defines the meaning and structure of web content. It is often assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript.
Hypertext is text displayed on a computer display or other electronic devices with references (hyperlinks) to other text that the reader can immediately access. Hypertext documents are interconnected by hyperlinks, which are typically activated by a mouse click, keypress set, or screen touch. Apart from text, the term "hypertext" is also sometimes used to describe tables, images, and other presentational content formats with integrated hyperlinks. Hypertext is one of the key underlying concepts of the World Wide Web, where Web pages are often written in the Hypertext Markup Language (HTML). As implemented on the Web, hypertext enables the easy-to-use publication of information over the Internet.
In computer science, transclusion is the inclusion of part or all of an electronic document into one or more other documents by reference via hypertext. Transclusion is usually performed when the referencing document is displayed, and is normally automatic and transparent to the end user. The result of transclusion is a single integrated document made of parts assembled dynamically from separate sources, possibly stored on different computers in disparate places.
Theodor Holm Nelson is an American pioneer of information technology, philosopher, and sociologist. He coined the terms hypertext and hypermedia in 1963 and published them in 1965. According to a 1997 Forbes profile, Nelson "sees himself as a literary romantic, like a Cyrano de Bergerac, or 'the Orson Welles of software'."
In computing, a hyperlink, or simply a link, is a digital reference to data that the user can follow or be guided to by clicking or tapping. A hyperlink points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks. The text that is linked from is known as anchor text. A software system that is used for viewing and creating hypertext is a hypertext system, and to create a hyperlink is to hyperlink. A user following hyperlinks is said to navigate or browse the hypertext.
The Spanning Tree Protocol (STP) is a network protocol that builds a loop-free logical topology for Ethernet networks. The basic function of STP is to prevent bridge loops and the broadcast radiation that results from them. Spanning tree also allows a network design to include backup links providing fault tolerance if an active link fails.
Project Xanadu was the first hypertext project, founded in 1960 by Ted Nelson. Administrators of Project Xanadu have declared it superior to the World Wide Web, with the mission statement: "Today's popular software simulates paper. The World Wide Web trivialises our original hypertext model with one-way ever-breaking links and no management of version or contents."
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer.
ZIP is an archive file format that supports lossless data compression. A ZIP file may contain one or more files or directories that may have been compressed. The ZIP file format permits a number of compression algorithms, though DEFLATE is the most common. This format was originally created in 1989 and was first implemented in PKWARE, Inc.'s PKZIP utility, as a replacement for the previous ARC compression format by Thom Henderson. The ZIP format was then quickly supported by many software utilities other than PKZIP. Microsoft has included built-in ZIP support in versions of Microsoft Windows since 1998 via the "Plus! 98" addon for Windows 98. Native support was added as of the year 2000 in Windows ME. Apple has included built-in ZIP support in Mac OS X 10.3 and later. Most free operating systems have built in support for ZIP in similar manners to Windows and Mac OS X.
An HTML element is a type of HTML document component, one of several types of HTML nodes. The first used version of HTML was written by Tim Berners-Lee in 1993 and there have since been many versions of HTML. The current de facto standard is governed by the industry group WHATWG and is known as the HTML Living Standard.
In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer references a location in memory, and obtaining the value stored at that location is known as dereferencing the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture.
In computer science, canonicalization is a process for converting data that has more than one possible representation into a "standard", "normal", or canonical form. This can be done to compare different representations for equivalence, to count the number of distinct data structures, to improve the efficiency of various algorithms by eliminating repeated calculations, or to make it possible to impose a meaningful sorting order.
ZigZag is a data model, invented by Ted Nelson, that deconstructs the spreadsheet to allow irregular relations, at the same time generalizing the idea to multiple dimensions.
Computer Lib/Dream Machines is a 1974 book by Ted Nelson, printed as a two-front-cover paperback to indicate its "intertwingled" nature. Originally self-published by Nelson, it was republished with a foreword by Stewart Brand in 1987 by Microsoft Press.
RDFa or Resource Description Framework in Attributes is a W3C Recommendation that adds a set of attribute-level extensions to HTML, XHTML and various XML-based document types for embedding rich metadata within Web documents. The Resource Description Framework (RDF) data-model mapping enables its use for embedding RDF subject-predicate-object expressions within XHTML documents. It also enables the extraction of RDF model triples by compliant user agents.
Roger Everett Gregory is a US computer programmer, technologist, and scientist. Gregory's work in project Xanadu made him one of the earliest pioneers of hypertext technology, which helped lay the foundations for the hyperlink technology that underlies the World Wide Web. Gregory attended the University of Michigan as a mathematics major. In the 1970s, he founded the Ann Arbor Computer Club, similar to the West Coast's Home Brew Computer Club.
Enfilades are a class of tree data structures invented by computer scientist Ted Nelson and used in Project Xanadu "Green" designs of the 1970s and 1980s. Enfilades allow quick editing, versioning, retrieval and inter-comparison operations in a large, cross-linked hypertext database. The Xanadu "Gold" design starting in the 1990s used a related data structure called the Ent.
The Internationalization Tag Set (ITS) is a set of attributes and elements designed to provide internationalization and localization support in XML documents.
Semantic HTML is the use of HTML markup to reinforce the semantics, or meaning, of the information in web pages and web applications rather than merely to define its presentation or look. Semantic HTML is processed by traditional web browsers as well as by many other user agents. CSS is used to suggest its presentation to human users.
Hypertext is text displayed on a computer or other electronic device with references (hyperlinks) to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Early conceptions of hypertext defined it as text that could be connected by a linking system to a range of other documents that were stored outside that text. In 1934 Belgian bibliographer, Paul Otlet, developed a blueprint for links that telescoped out from hypertext electrically to allow readers to access documents, books, photographs, and so on, stored anywhere in the world.