Hypertext

1
Hypertext

• Kasper Østerbye
• IT University of Copenhagen
• May 2008

2
Agenda

• What is a link
• Selected aspects of hypertext history
• Architecture of a hypertext system
• Why hypertext systems are hard to build
• A success story (wiki)
• Scripting in hypertext

3
Links

• Links in the database are not stored as part of
  the contents, i.e., the b and g links are not
  part of A.
• The visible rectangles on the screen are called
  link-markers.
• There can me more than one rendering of the
  hypertext database
• One could render the B node in lined in A
• Outline mode starting in A
• Graph like

4
Macro literary systems

• Vannevar Bush, Memez, 1945
• Microfilm technology
• Links
• Trails
• Authoring/Reading integrated
• Douglas Engelbart, NLS/Augment 1968
• Ted Nelson, Xanado
• Unclear if it was ever implemented
• Randall Trigg, Textnet

5
The mother of all demos

• Doug Englebart, Fall Joint Computer Conference
  (FJCC) 1968
• NLS/Augment
• 3-5 copy, cut, paste - mouse
• 1530 Graph, Hypertext
• 5700 Video collaboration

6
Knowledge worker

• Shared information
• Shared analysis
• Shared annotations
• Shared linking
• Multimedia (text, graphs and graphics)
• Problem exploration systems (Conklins own area)

7
gIBIS

• Structural argumentation
• Specific link types
• Known node and link types enable computer tooling
  on top
• overviews
• un-argued positions
• issues with only one position
• Problem Hard to use, not how people think. The
  fundamental idea of structured argumentation
  tools were dismissed at a panel discussion at one
  of the Hypertext conferences.

8
Notecards, 1987
9
Essence of HT - used in the creative phase

• Focus of the HT research was on augmenting the
  human intellect
• WWW also had that focus in the very beginning -
  get and put are fundamental parts in http.
• The graphic browsers ignored the write part as an
  integrated aspect.
• Security and access rights was a non-issue

10
Reading and authoring

• Follow link
• get content from some database
• get links on that content from link database
• render content with links
• Make link
• Mark source and destination marker of link
• Add additional info reg. link - eg. type of link
• Translate markers into persistent anchors.
• Store link, info, and anchor in link database

Editor
Links
Content
Content
11
What is a link

• Different kinds
• Hierarchical
• Referential
• Keyword
• Additional structure
• Name
• Type
• Cardinality (linking more than 2 nodes)
• Attributes (date, owner, color,...)

• Source
• Node
• Inter-node location
• Destination
• Node
• Inter-node location
• In viewer
• Region/Link marker
• Rendering issue
• Tracking links when cut/copy/paste
• In database
• Anchor definition (persistent link marker)
• Media independent storage
• Tracking anchors for changed contents

12
Following a link

• Follow link
• Click on a link marker in the editor
• Get link id from the link marker
• Retrive link from link database
• Retrive destination node D from content base
• Search link database for links which have the
  source in D
• Render D with link markers for all links

Editor
Links
Content
Content
13
Authoring a link

• Follow link
• Get selection from the rendering of the source
• Get the selection from the rendering of the
  destination
• Open a link-editor to allow entering of
  link-kind, link-type, and other attributes
• Transform the source and destination selections
  into anchors.
• Store the link into the link base
• Update the renderings to show the new link
  (create link markers)
• 0

Editor
Links
Content
Content
14
Typical shortcuts

• Annotate
• Create a new link of type annotation to a new
  node by one key-stroke
• New subsection
• Create a new structural link to a new node by one
  key-stroke
• Current selection to existing node reference
• Create a new link of default type to an existing
  node from the current selection. The mouse cursor
  changes to indicate special mode, and link is
  created when a special key is pressed.

15
Hypertext system architecture
16
Computer supported cooperative work

• B monitors contents in DB2
• A creates a new node in DB2
• Bs viewer is notified, and
• get new content
• retrieves links from LB1 and LB2
• renders contents with links
• ? Is there a difference in what A and B sees?

B
A
LB1
LB2
DB1
DB2
17
Third party formats

• Content is in proprietary format
• How to add and author links?

Editor
Links
Content
18
Hypertext on the web - wiki wiki

• Blending authoring and reading
• History
• Discussion
• Blending into www
• Single shared view
• No personal annotations
• No personal linkages

• http//en.wikipedia.org/wiki/Wiki
• http//wiki.secondlife.com/wiki/LlSitTarget
• http//www.itu.dk/research/pls/wiki/index.php/AMP-
  Spring2008

19
Linearization

• Scripting

20
www and hypertext

• WWW is today a general user interface platform
• WWW has very poor support for hypertext authoring
• Link source is well supported