T.Sharon-A.Frank 1 Multimedia Hypertext and Hypermedia

2 T.Sharon-A.Frank Hypertext Issues Hypertext History Hypertext Representation Application Example (Nielsen) Hypertext Navigation Aids

3 T.Sharon-A.Frank Normal Text vs. Hypertext

4 T.Sharon-A.Frank Hypertext Text augmented with links: –Link: pointer to another piece of text in same or different document. –Navigational metaphor  User follows a link from its source to its destination, usually by clicking on source with the mouse. –Use browser to view and navigate hypertext.

5 Memex – Vannevar Bush, 1945 – Concept of linked documents; photo-mechanical realization never implemented. Xanadu – Ted Nelson, late 1960s onwards – Hypertext defined; intended as global system but no real popular implementation. Hypercard – Apple, 1987 – Shipped with every Mac; popularized concept. World Wide Web – 1993 Glimpse into Hypertext History

6 T.Sharon-A.Frank MEMEX MEMEX – MEMory EXtender by Vannevar Bush –Developed 1932 –Publication 1945 –Great Insights –Never implemented

7 T.Sharon-A.Frank Envisioned Memex

8 T.Sharon-A.Frank Linearity vs. Non-linearity

9 T.Sharon-A.Frank Hypertext View

10 Hypertext is not usually read linearly (from start to finish). Links encourage branching off. History and back button permit backtracking. Not an innovation, but the immediacy of following links by clicking creates a different experience from traditional non-linearity (e.g. cross-references in encyclopedia). Non-linearity

11 T.Sharon-A.Frank Hypermedia

12 T.Sharon-A.Frank Hypermedia View

13 T.Sharon-A.Frank A Web site is Hypermedia

14 T.Sharon-A.Frank Hypertext/media structure is a graph Nodes – Information Units Edges – Links to other Information Units Navigation: traversing through the graph SourceDestination

15 T.Sharon-A.Frank Graph is Media Independent Text Graphics Still Images Audio Animation Motion Video ABC

16 T.Sharon-A.Frank Various destination anchors

17 Simple unidirectional links: – Connect single point on one page with a point on another page (e.g. Web). Extended links: – Regional links (ends may be regions within a page). – Bidirectional links (may be followed in both directions). – Multi links (may have more than two ends). Types of Links

18 T.Sharon-A.Frank Hypertext Abstract Machine (HAM) Presentation Level Hypertext Abstract Machine (HAM) Level Host File Systems Level [Campbell & Goodman, 1988]

19 T.Sharon-A.Frank Dexter Model (88-90)

20 T.Sharon-A.Frank Flag Model (HT’96)