Hypertext Kasper Østerbye IT University of Copenhagen May 2008

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

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

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

The mother of all demo’s  Doug Englebart, Fall Joint Computer Conference (FJCC) 1968  NLS/Augment  3-5 copy, cut, paste - mouse  15:30 Graph, Hypertext  57:00 Video collaboration

Knowledge worker  Shared information  Shared 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.

Notecards, 1987

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

Reading and authoring Follow link: a) get content from some database b) get links on that content from link database c) render content with links Make link a) 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 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 editor b) Get link id from the link marker c) Retrive link from link database d) 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 Editor Links

Authoring a link Follow link: a) Get selection from the rendering of the source b) 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) 0 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 DB2  A creates a new node in DB2  B’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   et et  x.php/AMP-Spring x.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