CSA3080: Adaptive Hypertext Systems I

1. CSA3080:Adaptive Hypertext Systems I Lecture 8:Hypertext Issues and the WWW Dr. Christopher Staff Department of Computer Science & AI University of Malta 1 of 21 cstaff@cs.um.edu.mt

2. Aims and Objectives • DHRM has very few implementation examples • The WWW, while not DHRM-conformant, is the single largest and most popular example of a distributed hypertext system • There are general hypertext issues, which DHRM attempted to address • The implementation of the WWW has led to other issues, which AHS attempt to address 2 of 21 cstaff@cs.um.edu.mt

3. Issues in Hypertext • Halasz (again :-)) wrote “Reflections…” in 1987 • It re-surfaces frequently at conferences on Hypertext • Provoking much discussion and updating • Halasz believed that “hypertext” would “disappear”, becoming an underlying mechanism for storing and linking information • Hypertext is still very much “in our face”… 3 of 21 cstaff@cs.um.edu.mt

4. Issues in Hypertext • “Seven Issues” References: • Reflections on NoteCards: seven issues for the next generation of hypermedia systems Frank,G. Halasz July 1988  Communications of the ACM, Volume 31, Issue 7 • ACM Journal of Computer Documentation (JCD), Volume 25, Issue 3 (http://portal.acm.org/toc.cfm?id=507317&type=issue&coll=ACM&dl=ACM&CFID=14254782&CFTOKEN=22435962). Entire issue devoted to “Seven Issues” • Seven Issues, Revisited. Panel Session, Hypertext ‘02. 4 of 21 cstaff@cs.um.edu.mt

5. The Seven Issues • Search and Query • Composites • Virtual Structures and dynamic information • Computation • Versioning • Support for collaborative work • Extensibility and Tailorability 5 of 21 cstaff@cs.um.edu.mt

6. Issues in Hypertext • Search and Query • as part of the hypertext model! • Current generation web has 3rd party search engines • Semantic Web *may* be able to refer to objects via their content, rather than URL (or at least, do it seamlessly!) 6 of 21 cstaff@cs.um.edu.mt

7. Issues in Hypertext • Composites • Web still doesn’t really support composites, though it can be achieved through dynamic HTML • But watch out for the Dark Web! 7 of 21 cstaff@cs.um.edu.mt

8. Issues in Hypertext • Virtual structures and dynamic information • So that the network can reconfigure itself according to the information it contains • Self-repairing links, links which bind to the best destination when it becomes available • Web approximates by redirecting to relocated information… 8 of 21 cstaff@cs.um.edu.mt

9. Issues in Hypertext • Computation • The end of a link can be a computation • The computation can decide what destination to visit, etc. • Web can do… e.g.., search engines! 9 of 21 cstaff@cs.um.edu.mt

10. Issues in Hypertext • Versioning • Shudder!!!! • Some systems/editors provide versioning (e.g., SCCS for source code development) • Web absolutely does not! 10 of 21 cstaff@cs.um.edu.mt

11. Issues in Hypertext • Support for collaborative work • Web/internet is a collaborative place. We are sometimes aware of other people in this space • Yet collaboration on, say, development of a web site is not possible within the Web (i.e., there is no explicit support for it). • Web site updating is merely replace currently live page in Document directory • No locking, etc., of files supported 11 of 21 cstaff@cs.um.edu.mt

12. Issues in Hypertext • Extensibility and tailorability • The “programmable” Web • Servers can be independently configured/extended • Plug-ins increase support for doc types • Web browsers can be configured for individual user, etc 12 of 21 cstaff@cs.um.edu.mt

13. WWW • The WWW is the single largest example of a distributed hypertext system • But is it a good example of a hypertext system? • And does it really matter if it’s a good example? 13 of 21 cstaff@cs.um.edu.mt

14. WWW • The WWW was not developed with a formal model in mind • Based on the concept of a Uniform Document Identifier, HTTP, and a standard markup language (HTML) • TCP/IP used as the transport protocol • Link source is marked by <A HREF> tag, with an embedded destination • Reference: • Berners-Lee, T., et. al., 1994, “The World-Wide Web” in Communications of the ACM, Vol. 37, No. 8. August 1994. 14 of 21 cstaff@cs.um.edu.mt

15. WWW • Simple model, yet powerful • Can share documents across the globe • Anyone can author a Web page • With extensions to original model, can create pages dynamically • Can manipulate multimedia data • HTML still presentation markup language 15 of 21 cstaff@cs.um.edu.mt

16. WWW and DHRM 16 of 21 cstaff@cs.um.edu.mt

17. WWW and DHRM 17 of 21 cstaff@cs.um.edu.mt

18. Semantic Web • Next generation web attempts to overcome some of these problems • Thing is, “fixes” are built on top of existing structure, rather than bottom-up re-modelling 18 of 21 cstaff@cs.um.edu.mt

19. Semantic Web 19 of 21 cstaff@cs.um.edu.mt

20. Semantic Web 20 of 21 cstaff@cs.um.edu.mt

21. So… does it matter? • The (Semantic) Web will address some of the concerns in Seven Issues (but don’t forget about the other issues addressed by AHS!) • SemWeb promises to become a knowledge base that may eventually remove the need for user navigation all together 21 of 21 cstaff@cs.um.edu.mt