This is of course very important! But just adding an alert in the
client before spending money is not a complex change. It might just be
annoying to the user (had you rather be annoyed or spend $$$ ?) The
user could also want to authorize access without warning to trusted
data sources, e.g. a pay-by-time database that he uses frequently
(with the stress of the ticking $ clock in the corner...)
> Also, attention links are not sufficient for a charging. They
> support a model where I am charged once per read, no matter how much
> of the document I read. But it seems likely that there might be need
> for other charging models.
For a discussion of the many problems of a read-based charging scheme
(which was to be implemented in Xanadu as an answer to the Copyright
issues), you may want to read a paper presented at the Hypertext'91
conference in San Antonio, by Pamela Samuelson and Robert Glushko,
"Intellectual Property Rights for Digital Library and Hypertext
Publishing Systems: an Analysis of Xanadu" (unfortunately not
available online to my knowledge...)
-- Jean-Francois Groff (jfg@info.cern.ch) World-Wide Web initiative CERN, ECP division, CH-1211 Geneva 23, Switzerland Phone +41 22 767 3755 -- Fax +41 22 767 7155-- "Life may at times be boring, but is it more fun to be dead ?" -- Alcor