Hypertext: An Introduction and Survey

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Hypertext An Introduction and Survey

• By
• Lene Ane Ingrid

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An Introduction

• Hypertext An Introduction and Survey
•  
• Hypertext Implementations (different hypertext
  systems)
•  
• The essence of hypertext
•  
• The advantages and disadvantages uses of
  hypertext
•  

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Hypertext An Introduction and Survey

• Introduction what is hypertext
• Glimpse of using hypertext

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Introduction what is hypertext

• Hypertext non-linear text
• Computer based links are a central issues
• One to one correspondence between nodes in the
  database and windows desktop (dont need to be
  like that replacement link Guide)

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Hypertext database
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What is not hypertext?

• Windows systems
• File system
• Outline editor
• Database Management Systems

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Glimpse of using hypertext

• Windows can contain any number of links icons.
• The database is a network of textual nodes which
  can be thought of as a kind of hypertext
• Windows on a screen correspond to nodes in the
  database.
• Standard Windows system operations are supported.

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Glimpse of using hypertext 2

• The user can easily create new nodes and new
  links to new nodes.
• The database can be browse in 3 ways
• By following links and opening windows to examine
  their contents
• By searching the network for some keywords.
• By navigating around the hyperdocument using a
  browser

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Hypertext Implementation

• 1.      Macro literary system
• 2.      Problem exploration tools
•   3.      Browsing systems
• 4.      General hypertext technology

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Macro literary system

• Is the study of technologies to support large
  on-line libraries in which interdocument links
  are machine-supported, that is all publishing,
  reading collaboration and criticism take place
  within the network.

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Bushs Memex

• Bush proposed a system called the "Memex" in
  1945, in his article As we May Think
• Store information on microfilm which would be
  kept on the user's desk
• Tying two items together

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Engelbart s NLS/Augment

• Was designed for office automation to store
  research's paper, reports etc.  
• Like others early hypertext systems NLS
  emphasized 3 aspects
• A database (of nonlinear text).
• A viewer filter (which selected information from
  this database).
• A views (which structured the display of this
  information for the terminal).
•  
• Files in NLS were structured into a hierarchy of
  segments called statements

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Augment
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Nelsons Xanadu project
It is a write-once system Links are
created by users. The original document remains
the same. Uses much attention to re-design and
re-implementation of file systems.
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Triggs Texnet
Randall Trigg wrote the first thesis on
hypertext. High-level financial plan that
defines financial model, pricing assumptions,
and reviews yearly expected sales and profits for
the next three years. Textnet system as a
supporting nonlinear text. Relationships
between nodes. First definition of a path, as a
ordered lists of nodes.
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Problem exploration tools

• Are tools that support early unstructured
  thinking on a problem when many disconnected
  ideas come to mind.

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 Issue- Based Information System

• The IBIS aids participants in defining problems
  and reducing the kinds of repetitive exposition
  that are all too common in less-structured
  forums.
• IBIS uses a small set of document types to encode
  an entire discussion. Forcing the discussion into
  this format can be tricky.
• IBIS has 3 types of nodes.
• - Issues
• - Positions
• - Arguments

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Issue- Based Information System
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SYNVIEW

• Is similar to in concept to Rittels, IBIS but
  goes in a different direction.
• It proposes that the user in addition to proposes
  that their own issues and arguments access
  previous posting as to their validity and
  relevance. This is done by a kind of voting. The
  various display of the argument structure show
  the values for each posting allowing readers to
  focus, if they choose to, on those argument
  trails having the highest voted validity.

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UNCs WE

• Writing enviroment call WE, are designet for
  experimental platform to study what tools and
  facilities there vill be useful in a writers
  enviroment.
• WE is support the upstream part of writing and
  contains 2 major view windows, one graphical and
  one hierarchical
• WE use a relational database for storage of nodes
  and links.
• The user use a mous to point to a selected node.

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Outline Processors
An outline prossor is a word processing program
which is specialized for processing outlines, in
that its main commands deal with movement among
creation of and modification of outline
entries. Have a simple text editors. Open up just
those entries that are relevant. Each outline
entry can have Textual body of any lenght. Body
can appear or dissappear with a single keystroke.
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Structured browsing systems

• Used primarily to support applications with a
  high amount of information
• Easy to learn and easy to use
• Adding new information is not well supported
• The user is often only able to read information

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Shneidermans hyperTies

• Started University of Maryland's Human-Computer
  Interaction Laboratory.
• It provides authoring and browsing tools. A
  node may contain an entire article that may
  consist of several pages.
• Links are represented by highlighted words or
  embedded menus which can be activated using e.g.
  a keyboard
• Readers can preview links before actually
  traversing them.
• The user interface is relatively simple due to
  the original emphasis on museum information
  systems or kiosks.

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Shneidermans hyperties
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ZOG/KMS
KMS the commercial successor of the ZOG
system developed at CMU developed/marketed by
Knowledge Systems first version of KMS
available in 1983 designed to manage fairly
large hypertext networks across local area
networks KMS is based on the basic unit called
the frame. A frame can contain text,
graphics, or images. Frames are connected to
other frames via links.
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ZOG/KMS 2

• Links are of two types - tree items to
  represent hierarchical relationships -
  annotation items to represent referential
  relationships.
• There is no distinction between browsing and
  authoring modes.
• Users can make changes to a frame or create
  links at any time and these changes are saved
  automatically
• KMS supports features such as aggregation,
  keyword searching, tailorability, collaboration,
  concurrency control, data integrity and security.
  
• It has been used for collaborative work,
  electronic publishing, project management,
  technical manuals and electronic mail.

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Symbolics Document Examiner

• Runs on LISP as an on-line help system, and also
  designed to browse through for example a
  technical manual
• The user can place bookmarks on any topic so the
  user can move fast between bookmark topics
• The user supports on-line string search of whole
  words, leading substrings and embedded substrings
• It is not possible for the user to change the
  manual set but he can save the personalized
  bookmarks

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Emacs INFO Subsystem

• The help system is a used text editor
• Much like ZOG and KMS
• It uses a set of standard commands
• Primarily hierarchical but the user is able to
  jump into a different place in the hierarchy
• It can only display a single frame at a time

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General hypertext technology
These systems primarily purpose is
experimentation with hypertext itself as a
technology. For example for authoring,
programming, project management, legal research
and engineering design.
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Xerox PARCs NoteCards

• Was developed at Xerox PARC in the mid 1980s
• Is a general hypermedia system designed for many
  uses
• Designed to help people work with ideas
• The intended users are authors, researchers,
  designers, and other intellectual laborers
• Xerox Lisp (InterLisp) running on a Lisp machine

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NoteCards
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Xerox PARCs NoteCards

• Each node in the system equals a notecard.
• A card is represented as a small window on
  screen
• A attributes can be attached to cards
• It uses two way links
• It can specify the type of link
• Users can use graphical browser to edit network
  structure
• Edits made to browser representation affect
  underlying cards and links between them

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Guide
Guide was developed by Peter Brown as a research
project at the University of Canterbury,
U.K Commercially marketed by Office Workstations
Limited both on the IBM PC and Apple Macintosh.
(Multiple OS) First wide spread commercial
hypertext system Text and graphics are
integrated together in articles or documents.
Guide supports three different kinds of links
replacement links, note links and reference
links. Guide does not distinguish between the
author and the reader
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Intermedia

• Intermedia was developed in 1985
• It gathers different editors with a homogeneous
  approach. It can use the following editors
• InterText (text editor)
• InterDraw (graphics editor)
• InterSpect (3-D object viewer)
• InterPix (scanned image viewer)
• InterVal (timeline editor)

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Intermedia
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Intermedia 1

• The Intermedia author has the ability to create
  nodes, links, and link sets or webs within a
  template.
• Documents within the same template can be linked.
  
• Users can also link a document in a template to
  another document outside of the template.
• The user can specify the folder or directory
  under which each document is created and also the
  folder where the template has to be duplicated.
• The user can also name and save a template for
  future use.

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Intermedia 2

• The system will make copies of all folders and
  documents and automatically link them just as the
  original template was linked.
• When a template is duplicated, all associated
  documents and links can be easily accessed in new
  folders.
• Contents of documents can be edited.
• The user can easily find out which template was
  used to make a new hypertext collection.
• The original template itself is write-protected
  so that users do not edit it accidentally.

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Tektronix Neptune part 1

• Is partially designed as an open, layered
  architecture
• Front end Smalltalk-based user interface
• Back end a transaction based server called the
• Hypertext Abstract Machine (HAM)
• HAM maintains a complete version history of each
  node in the hyperdocument.
• It provides rapid access to any version of a
  hyperdocument
• It provides distributed access over a computer
  network
• It provides synchronization for multi-user access
• It provides a complex network versioning
• It provides a transaction-based crash recovery

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PlaneText

• Based on the unix file system
• In Planetext each node is a unix file.
• Links are implemented as pointers in separate
  files, so the hypertext documents are not changed
  when references are made between them.

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CREF

• A specialized text and graphics editor, but also
  used to investigate more general typertext design
  issues.
• Chunks of text, called segments, are the nodes
  tin the system.
• The segments are arranged in linear series, and
  can have keywords and various links to other
  segments.
• The system organizes into collections which can
  be defined implicitly by a predicate or
  explicitly by a list.
• Types of links
• Reference links
• Summarizes links
• Supersedes links
• Precedes links
• Multiple analysts can create their own theories
  about protocol, using the same segmented data.
• Every analyst imposes his own structure on the
  data

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Tektronix Neptune part 2

• It can use different kinds of browsers. E.g.
• A graph browser
• A document browser
• A node browser
• Attribute browsers
• Version browsers
• Node difference browsers
• Demon browsers
• Nodes and links may have an unlimited number of
  attribute/value pairs
• There are special high-speed included for
  queering the values of these pairs in the entire
  hyperdocument

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Neptune
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Linking 1

• Links and nodes are the basic building blocks of
  hypertext.
• A hypertext system is made of nodes (concepts)
  and links (relationships).
• A node usually represents a single concept or
  idea.
• It can contain text, graphics, animation, audio,
  video, images or programs.
• It can be typed thereby carrying semantic
  information.
• Nodes are connected to other nodes by links.
• Links can be either referential or hierarchical

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Linking
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Links

• To qualify as hypertext, links should Require
  no more than a couple of keystrokes to traverse
  Be very fast, requiring only briefest delay to
  traverse to linked material
• Links can serve many functions including
  Connect document reference to the document
  itself Connect comment or annotation to
  information it refers to Provide organizational
  information
• Connect successive pieces of text (creating a
  linear flow) Connect a figure or table entries
  to more detailed descriptions

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Types of links

• Referential links
• Explicitly connect two points in a hypertext
• Are the standard type of hypertext link
• Organizational links
• Are used to organize information
  hierarchically
• Connect a parent node with its children to
  form a tree subgraph in a hypertext network

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Hypertext nodes

• Encourage modularization of ideas
• provides intermediate level of machine support
  for representation
• Lies between characters and files
• Can be typed
• useful capability for processing internal
  structures of nodes
• Can be semistructured, instead of blank slates
• typed nodes that contain labeled fields and
  spaces for field values
• Enables creation of template nodes
• assist users in being complete, and assist in
  computer processing of node information
• Can be grouped (into composites)
• support aggregation
• useful capability in range of different areas

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The advantages and uses of hypertext

• Ease of tracing links
• Ease of creating new references
• Information structuring
• Global views
• Customised documents
• Modularity of information
• Consistency of information
• Task stacking
• Collaboration

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The disadvantages of hypertext

• The risk of disorientation while navigating the
  information space is one of the major usability
  problems with hypertext systems.
• Cognitive overhead is another problem with
  hypertext systems. It may be difficult for group
  members to become accustomed to the additional
  mental overhead required to create and keep track
  of links.
• In general the additional effort and
  concentration necessary to maintain several tasks
  or trails at one time may be experienced as a
  burden.

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