From: barmar@alum.mit.edu   
      
   In article <1phqkeh0a1uotgg9ub0h1dptuintjiqtnm@4ax.com>,   
    Robert Wessel  wrote:   
      
   > On Fri, 09 Aug 2019 05:12:11 -0500, Robert Wessel   
   >  wrote:   
   >   
   > >On Fri, 9 Aug 2019 00:58:16 -0700 (PDT), groovee@cyberdude.com wrote:   
   > >   
   > >>I was just shopping groceries on a site. I searched "potato" on it and got   
   > >>a list of results. Then I went to some other page. *Then* I happened to   
   > >>click the Back button. Firefox showed me a "We need to resend your query to   
   > >>the server"...blah blah. What does this mean??? Can Firefox tell the   
   > >>difference between a static page and a dynamic one? What is the   
   > >>relationship between dynamic pages and caching exactly? If a page is   
   > >>dynamic, does that automatically MEAN that the server needs to be hit every   
   > >>time it's fetched? (doesn't APPEAR to be the case - there are other sites   
   > >>which do not show this behaviour).   
   > >>I suspect what happened was that these guys turned OFF the cache totally   
   > >>for that page - like, why?? :) Are there going to be 2000 different   
   > >>varieties of potatoes being added to the site/sec?? :) If you were the site   
   > >>maker, is there some way to turn off caching ONLY FOR DYNAMIC PAGES,   
   > >>somehow?? - just out of curiosity?? How?? (nasty Apache conf file fiddling,   
   > >>right?? :( )   
   > >   
   > >   
   > >If I understand your question correctly, this is the result of a web   
   > >page using a POST (as opposed to GET) HTTP request.  Unlike GETs,   
   > >POSTs may impact state on the server, so cannot be safely (re)sent -   
   > >that's what the browser is warning you about.  Usually called a   
   > >"postback".   
   >   
   >   
   > As to caching, it can be controlled on a per-page basis with the   
   > Cache-Control parameter, although it doesn't directly prevent caching,   
   > it is supposed to make the browser use one of the "If-" parameters to   
   > validate the page - but that doesn't usually result in the "need to   
   > resend" message.   
      
   But browsers never cache the result of a POST, AFAIK, so cache control   
   is irrelevant there.   
      
   --   
   Barry Margolin   
   Arlington, MA   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)