1 Todays web is far from perfect Typed links and nodes The web is - PDF document

What is hypermedia? � Hypertext; hyperfilm; hypermedia: � Curiousity: terms coined by Ted Nelson Hypermedia 1 � Berners-Lee’s WWW proposal (1965, ◊ 11): from 1990 � “Let me introduce the word History and basic concepts ‘hypertext’ to mean a body of written or pictorial material interconnected in such a complex way that it could not conveniently be presented or represented on paper.” � The World-Wide-Web (Berners-Lee, 1991, ◊ 54) is an example of a hypermedium New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 2 Pre-WWW hypermedia systems Basic hypermedia terminology � Xanadu � Node � Nelson (1965) � Link � NLS/Augment � Anchor (node) � Engelbart (1968, ◊ 16) � Destination (node) � ZOG/KMS � Carnegie Mellon (1975) � Aspen Movie Map � MIT (Lippman, 1978) � Intermedia � Brown University (1985) � HyperCard � Apple Computer (1987) New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 3 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 4 Some possible questions about hypermedia links Today’s web is far from perfect � How is it perceived by the user? � The web is in many ways a very limited hypermedia system if � Does it have a clear existence? compared to visions of Nelson and � What does the link mean? Of what Engelbart. Yet, very little has been type is the link? done to improve the core of this � What info does the anchor reveal hypermedium since 1993. about the destination? � How? � What is the cost of following the link? � How persistent is the link? New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 5 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 6 1

Today’s web is far from perfect Typed links and nodes � The web is in many ways a very � Typed links and nodes � Helps authors organize � Similarly, node types categorize limited hypermedia system if information more effectively node content � Link attributes and structure- compared to visions of Nelson and based query � Provides context to readers Engelbart. Yet, very little has been � Connecting occurrences: done to improve the core of this transclusions, warm links and hot hypermedium since 1993. � Link type examples: links � Bieber et al. (1997) suggest the � “explanantion” � Example: gIBIS (Conklin & � Annotations and public or private following enhancements: Begeman, 1989) uses typed nodes � “further details” links and links � “contrasting argument” � Computed, personalized links � A typed link conveys the � External link databases and link relationship between the link’s update mechanisms destination and the link’s anchor � Local and global overviews � Trails and guided tours � Backtracking and History-based Navigation New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 7 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 8 Connecting occurrences: transclusions, warm Link attributes and structure-based query links and hot links � Link attributes (“labels”) can add � Transclusion – a mechanism for � Warm links – node content even more semantic info to links having the exact same object becomes updated on user request (node content) exist in multiple � Makes it possible to make the � Hot links – node content becomes places links context-sensitive automatically updated when the � Note 1: not copies, more like node is about to be displayed � Readers should also be allowed to “shortcuts” define labels � Eliminates the problem of manual � By supporting more advanced link updating of node object copies attributes, structure-based queries when the original changes can be asked (compare with today’s free-text based queries) � Note 2: we are talking about parts of nodes, not whole nodes � The web can become more like a database New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 9 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 10 Annotations and public or private links Computed, personalized links � Annotation provides means to � NSCA Mosaic 2.6 supports � The reader should be allowed to comment on node content personal, workgroup, and public specify rules for automatic link annotations generation � Very common in non-WWW hypermedia systems, why not in � Example: a sales agent in an the WWW? insurance company could specify to the hypermedia system that � What about going further, allowing names of customers would readers to modify the node automatically be linked to every content itself? insurance policy ever held by that � Need for access permission customer control like in ordinary file systems New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 11 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 12 2

External link databases and link update Local and global overviews mechanisms � Enables users without write-access � Global overview diagrams provide to nodes to create links an overall picture and can also nevertheless provide anchors for local overview diagrams � The links are not hardcoded into the node but are stored externally � Local overview diagrams provide a fine-grained picture of the local neighborhood of a node � Both serve as navigational aids New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 13 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 14 Trails and guided tours Backtracking and History-based Navigation � The concept of trails or paths are � Helps managing detours taken from Vannevar Bush (1945) � Reduces cognitive overhead � Trails connect a chain of links � Many different kinds of through information spaces, backtracking has been proposed in providing context for viewing and the literature understanding a series of � Common browsers use the documents (nodes). “stack” metaphor � Authors can prepare multiple “recommended” trails tuned to different readers New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 15 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 16 Video clips illustrating hypermedia � Douglas Engelbart’s NLS/Augment � Pederson’s 3D navigation vision demo from 1968. from 1997. New Media � demo video � Video clip End of hypermedia I – history and basic concepts New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 17 New Media 2006 | Thomas Pederson, Dept. of Computing Science, Umeå University, Sweden 3