Let's see how this goes if we substitute "book store" for "caching server"
  
  Because anyone running a caching server runs the dual risk of presenting 
  out-of-date information to their users and can be in direct violation of 
  international copyright law.
Yes, a book store could sell the old edition or let its customers Xerox books 
and never pay the publisher.  Bookstores even get to return unsold books for 
credit.  For paperbacks, at least, they don't even have to return the whole 
book, only the cover.  They can (and some do) sell the rest (this is 
physically possible, not legal).
  
  The publisher holds complete responsibility over their product, in
  content, presentation, timeliness and distribution.  By running a caching
  server on my content, you are robbing me of any control I might have over
  the timeliness and distribution. 
Yes, as does the bookstore.
  
  You can provide no guarantee that the versions that you present to your
  users are accurate or timely.  Further, I have no idea of the number of
  consumers who view my content through your cache or what they view, how
  and when. 
Yes
  
  Even assuming that you are acting in good faith, there are many kinds of 
  information which have value because of their timeliness.  Daily news and 
  stock quotes are two which immediately come to mind.
Yes, the bookstore should pull yesterday's newspapers and put out todays.
  
  Of course, I can mark my information as being uncacheable, but will you
  honor that request?  Your interest is to provide content to your users
  with as little impact on your communications resources as possible.  I
  believe that your goals and mine are not compatible. 
Well, my bookstore would be a lot more profitable if I could get the New York 
Times shipped by one week ground.
  
  The copyright issue is the more difficult one.   In light of the previous 
  argument, you are archiving an original work.  This is called "copying" 
  in copyright law and if it is done without permission, is against the law.
If I have the book on my shelf without having gotten it through a legitimate 
chain of transactions leading back to the publisher, I have also broken some 
laws.
  
...
  
  I expect that most professional publishers will not serve content to any 
  site which caches unless they can enter into a business relationship with 
  that site.  Unfortunately, this presents a very interesting N by N 
  problem, as publishers and caching servers proliferate.
Yes, this is an issue for bookstores too, and all other forms of retail 
commerce, actually.  That's why wholesalers and distributors, the infamous 
"middlemen" of common parlance, exist. 
  
My flipness aside, there are issues here, but they are issues which are 
amenable to technical solutions.  There are lots of authentication mechanisms 
for insuring that a publisher only "sells" to a "distributor" (cache) that she 
trusts, and to sign time critical material to that it identifiable as reliably 
as a newspaper is by the date on the top.  If anything, our problem is 
choosing among the alternatives, which is a problem largely because the 
choosing may decide a lot of things about who get rich from this new 
technology.
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Sarr Blumson                         sarr@citi.umich.edu
voice: +1 313 764 0253               FAX: +1 313 763 4434
CITI, University of Michigan, 519 W William, Ann Arbor, MI 48103-4943