Re: Transparency vs. Performance: survey of opinion

> I worry, however, about leaving it at that.  Certainly, there *are* cases
> in which caching is entirely inappropriate.  A simple `do whatever you
> please' model is inadequate in the following scenario:
> 
> Alice offers a book ordering service.  Bob sees that Alice has a book
> for sale, `HTTP Caching in Ten Easy Lessons.'  He fills out a form, and
> places an order for a copy to be shipped to him.  The copy goes out via
> air express, and arrives on Bob's desk the next day.
> 
> Bob peruses the book, and decides it would make a perfect birthday present
> for Carla.  He returns to Alice's service, fills out the form again, and
> submits it a second time with identical data. 

As I just reminded the caching subgroup, the issue of transparency that
we were talking about only applies to GET and HEAD requests.  Since the
above transaction would involve a response from a POST request, it does
not apply to this issue.  The HTTP/1.1 specification already forbids
clients from behaving as above.


 ...Roy T. Fielding
    Department of Information & Computer Science    (fielding@ics.uci.edu)
    University of California, Irvine, CA 92717-3425    fax:+1(714)824-4056
    http://www.ics.uci.edu/~fielding/