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One way of allow<strong>in</strong>g HTML documents to achieve the alternative l<strong>in</strong>k<strong>in</strong>g without extend<strong>in</strong>g the language itself<br />

is to use Java applets to implement the l<strong>in</strong>k<strong>in</strong>g specification. As a result, the language is kept simple and the<br />

extensions are achieved by the use of simple applet activation. We next comment how such specification can be<br />

done for the alternative l<strong>in</strong>k types discussed (more details <strong>in</strong> Pimentel [ & Buford 96]).<br />

Multi-end L<strong>in</strong>k. The Intermedia pop-up menu approach could be used to allow for multi-end l<strong>in</strong>ks <strong>in</strong> WWW<br />

pages. In this case, a Java applet is implemented that receives <strong>in</strong><strong>format</strong>ion regard<strong>in</strong>g anchors and dest<strong>in</strong>ation<br />

as parameters and, upon user activation, pops up a menu with labels associated to dest<strong>in</strong>ation anchors; each<br />

dest<strong>in</strong>ation anchor corresponds to the URL address to be loaded <strong>in</strong> case of selection.<br />

Pop-up L<strong>in</strong>k. A temporary pop-up l<strong>in</strong>k can specify what text is to be presented to the user by present<strong>in</strong>g the<br />

text explicitily. In this case, the Java applet responds to the l<strong>in</strong>k selection by popp<strong>in</strong>g up a w<strong>in</strong>dow conta<strong>in</strong><strong>in</strong>g<br />

the given text.<br />

Preview<strong>in</strong>g the Dest<strong>in</strong>ation of a L<strong>in</strong>k. When compared to the pop-up l<strong>in</strong>k, the specification for the<br />

Preview<strong>in</strong>g L<strong>in</strong>k needs one extra parameter: the address for the URL that is be loaded for the cases where the<br />

user chooses to complete the selection for the l<strong>in</strong>k.<br />

4. F<strong>in</strong>al Remarks<br />

The applets presented <strong>in</strong> this paper provide a low-cost way for the application designer to obta<strong>in</strong> some of the<br />

features of previous hypertext systems without wait<strong>in</strong>g for vendors and consortia to re-discover them. As the<br />

performance of Java implementations improves and the ability of applets to control more of the browser is<br />

provided, it is reasonable to expect that more powerful hypertext functionality will be available as add-on client<br />

functionality. The desirability of such customizibility of the hypertext system by application designers and end<br />

users was one of the key lessons of NoteCards [ Halasz 88], which used Lisp <strong>in</strong>stead of Java, and is still true<br />

today. Work is be<strong>in</strong>g carried out on the implementation of Java code support<strong>in</strong>g the l<strong>in</strong>k<strong>in</strong>g structures specified<br />

above and examples are available <strong>in</strong> [ Pimentel & Buford 96].<br />

5. References<br />

[Buford & Rutledge 96] Buford, J. & Rutledge, L. (1996). Third Generation Distributed Hypermedia Systems. Handbook<br />

of Multimedia In<strong>format</strong>ion Management.<br />

[Carr 96] L. Carr et al. (1996) Open In<strong>format</strong>ion Services. Proc. Fifth Intl. WWW Conference.<br />

[Halasz 88] Halasz, F. (1988). Seven Issues for Next Generation Hypermedia. CACM, July.<br />

[Ladd 95] Ladd, B & Capps, M & David-Stotts, P. & Furuta, R. (1995). Multi-Head Multi-Tail, Mosaic. Proc. Fourth Intl.<br />

WWW Conf.<br />

[Maurer 94] Maurer, H. (1994) Advanc<strong>in</strong>g the Ideas of the World Wide Web. Proc. Distr. Multimedia Systems and<br />

Applications.<br />

[Meyrowitz 86] Meyrowitz, N. (1986). Intermedia: The architecture and construction of an object-oriented hypermedia<br />

system and applications framework. Proc. Conf. OOPSLA.<br />

[Pimentel & Buford 96] Pimentel, M.G. & Buford, J. (1996). Non-Invasive Improvements to Hyperl<strong>in</strong>k<strong>in</strong>g with HTM<br />

(extended version). http://www.icmsc.sc.usp.br/~mgp/webnet96ext.html<br />

[Pimentel 94] Pimentel, M.G. (1994). Evaluation of alternative operations for brows<strong>in</strong>g hypertext. People and Computers<br />

IX, Cambridge.<br />

[Shneiderman 87] Shneiderman, B. (1987). User <strong>in</strong>terface design for HyperTies. Proc. Hypertext'87.<br />

Acknowledgements

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