REFLECTIONS ON NOTECARDS: SEVEN ISSUES FOR THE NEXT GENERATION OF HYPERMEDIA FRANK G. HALASZ

About NoteCards Developed at Xerox PARC by Frank Halasz, Thomas Morgan and Randall Trigg Workstation based Hypermedia System Used for analyzing information, constructing models, formulating arguments, designing artifacts and processing ideas System is a network of electronic notecards interconnected by typed links

Four Basic Constructs Notecards electronic generalization of the 3 x 5 paper notecard displayed using standard Xerox Lisp windows several types like text-based cards, animation cards,etc. Links typed, directional connection between a source card and a destination card

Four Basic Constructs Browsers notecard containing the structural diagram of a network of notecards the diagrams in browsers are computed by system Fileboxes specialized cards for managing large network of notecards by using an additional hierarchical category structure for storage and retrieval

1 st Generation Hypermedia Systems NLS/Augment, FRESS, ZOG Mainframe based Focused primarily on text nodes Little or no graphic capabilities Supported medium to large teams of workers sharing a common network

2nd Generation Hypermedia Systems Began in early 1980s Workstation based, research oriented systems NoteCards, Neptune, Intermedia Support graphics, animation nodes and fully formatted text nodes Meant for single users or small work groups

Diversity in Hypermedia Systems  Scope size of information database and user population varies  Browsing Vs. Authoring Browsing-oriented System - well-developed tools for information presentation and exploratory browsing. Eg. Interactive museum exhibits Authoring-oriented System – well-developed tools for creation and modification of the network. Eg. Document authoring systems  Target Task Domain designed to support specific task. Eg. Neptune supports software engineering and hence focuses on versioning

NoteCards Designed for small groups Authoring System General purpose hypermedia system Originally designed for use in idea processing in research environment

Seven Issues for the next generation Hypermedia Systems Issue 1:Search & Query in Hypermedia Network  Hypermedia is navigational access  For effective access query/search facility must complement navigation  Three classes of navigational applications 1. NoteCards meant for small user groups 2. Display-oriented representation tasks. Network is centered around a single display 3. On-line interactive presentations  Navigational access difficult when network changes and structure becomes heterogeneous

Seven Issues for the next generation Hypermedia Systems Issue 1:Search & Query in Hypermedia Network (Contd..)  Browsers made more effective by applying techniques like fish-eye views and graph flyovers  Content search and Structure search mechanisms can be introduced  Example Query - all subnetworks containing two nodes connected by a supports link, where the destination node contains the word “hypertext.”  For implementing structure search, a query language to describe hypermedia structures and a search engine capable of satisfying the queries must be developed

Seven Issues for the next generation Hypermedia Systems Issue 2: Composites – Augmenting the Basic Node and Link Model  Hypermedia models lack composition mechanism  Browsers cannot understand and display compositions  Fileboxes fail to differentiate between reference relations and inclusion relations  Documents can be seen at only one level  Solution is to add composition as a primitive construct in the basic hypermedia model

Seven Issues for the next generation Hypermedia Systems Issue 3: Virtual Structures for Dealing with Changing Information  Hypermedia data model is static and fragmentary  Problem of “premature organization”  Relaxation of strict titling and filing requirements will help  Virtual structures can be defined – requires query mechanism  Virtual composite allows user to create nodes dynamically at access time from other nodes, links and composites in the network  Virtual links are also possible

Seven Issues for the next generation Hypermedia Systems Issue 4: Computation in (over) Hypermedia Networks  Hypermedia systems are passive storage and retrieval systems  Notecards can be augmented with active computational engines for particular applications  Future hypermedia systems should function more like knowledge-based AI systems  Merging concepts from frame-based systems and object-based systems  Choice between active and passive system is a trade off between efficiency and generality

Seven Issues for the next generation Hypermedia Systems Issue 5: Versioning  NoteCards does not have a versioning system  Versioning not required for authoring, argumentation and idea processing tasks  Crucial for software development applications  Neptune provides time-based linear version thread for individual nodes and links  PIE uses a layer mechanism  PIE provides a collaborative system

Seven Issues for the next generation Hypermedia Systems Issue 6: Support for Collaborative Work  Collaborative work involves creating annotations, maintaining multiple organizations of a single set of materials, and transferring messages between asynchronous users  Notecards is a single user system  The mechanics of simultaneous multi-user access to common network must be improved – hard locking techniques are inappropriate  Social interactions must be provided

Seven Issues for the next generation Hypermedia Systems Issue 7: Extensibility and Tailorability  Hypermedia systems are flexible and hence have broad applications  Generic nature – a boon and a bain  NoteCards – lack of strategy manual showing uses of the system in specific tasks  Extensibility – extend the system with new functionality  Tailorability – tailor the existing functionalities to better suit the application  Achieved in NoteCards by providing programmatic access to system’s functionalities