Hypertext

Kasper ØsterbyeIT University of Copenhagen

May 2008

Agenda

What is a linkSelected aspects of hypertext historyArchitecture of a hypertext systemWhy hypertext systems are hard to buildA success story (wiki)Scripting in hypertext

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

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and a decompressor

are needed to see this picture.

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

implementedRandall Trigg, Textnet

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and a decompressor

are needed to see this picture.

The mother of all demo’s

Doug Englebart, Fall Joint Computer Conference (FJCC) 1968NLS/Augment

3-5 copy, cut, paste - mouse15:30 Graph, Hypertext57:00 Video collaboration

Knowledge worker

Shared informationShared analysis

Shared annotations Shared linking

Multimedia (text, graph’s and graphics)

Problem exploration systems (Conklin’s own area)

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.

QuickTime™ and a decompressor

are needed to see this picture.

Notecards, 1987

QuickTime™ and a decompressor

are needed to see this picture.

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

QuickTime™ and a decompressor

are needed to see this picture.

QuickTime™ and a decompressor

are needed to see this picture.

Reading and authoring

Follow link:a) get content from some

databaseb) get links on that

content from link database

c) render content with links

Make linka) Mark source and

destination marker of link

b) Add additional info reg. link - eg. type of link

c) Translate markers into persistent anchors.

d) Store link, info, and anchor in link database

Content Content

Editor

Links

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

Following a link

Follow link:a) Click on a link marker

in the editorb) Get link id from the

link markerc) Retrive link from link

databased) Retrive destination

node D from content base

e) Search link database for links which have the source in D

f) Render D with link markers for all links

Content Content

Editor

Links

Authoring a link

Follow link:a) Get selection from the

rendering of the sourceb) Get the selection from the

rendering of the destination

c) Open a link-editor to allow entering of link-kind, link-type, and other attributes

d) Transform the source and destination selections into anchors.

e) Store the link into the link base

f) Update the renderings to show the new link (create link markers)

g) 0Content Content

Editor

Links

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.

Hypertext system architecture

Computer supported cooperative work

B monitors contents in DB2A creates a new node in DB2B’s 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?

DB1 DB2

A

LB1 LB2

B

Third party formats

Content is in proprietary format

How to add and author links?

Content

Editor

Links

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

Linearization Scripting

www and hypertext WWW is today a general user

interface platform

WWW has very poor support for hypertext authoring

Link source is well supported