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Any way to disable tiles caching when updating periodically the web page? RRS feed

  • Question

  • Hello,

    We are using HDView as a (great) way to display our periodic images taken w/ a robotic camera.

    We take a set of images every 30 minutes or so on site, generate the panorama, and upload it to our website.

    On my PC (vista), once I have navigated over all tiles in my panorama, I no longer update them if I come back later on the same page, even if the panorama/tiles have changed (I mean 0_0.jpg as chenged, etc. but always in the same directory structure).

    If I change the directory name, looks like my HDview plugins considers that this is a completely new site/panorama, and loads correctly all tiles.

    If I clear my browser cache, no change.

    It runs the same in chrome IE9 firefox.

    It looks more like a (logical) HDview plugin optimization (to keep preceeding tiles when coming back to previously downloaded tiles)?

    Any ideas ?

    Thanks a lot for your support.

     

    Best Regards,

     

    François

     

    Saturday, July 30, 2011 3:41 PM

Answers

  • Francois,

    If you only control the client side, you'd need to reload the web page after clearing the browser cache in order to guarantee that HD View doesn't display any cached tiles.  However, if you also control the server side, there are ways to set the expiration date of content so that the browser will not cache it, or will only cache it for a specified time period.  If you can configure the web server so that the image tiles expire immediately, then every time you reload the web page, HD View would load fresh tiles and you would not need to clear the browser cache.  You could even edit the web page that displays the HD View control and add some JavaScript code that forces the web page to reload every 30 minutes to get the latest tiles (assuming the old tiles have expired from the browser cache).

    For more information on how web servers tell browsers the expiration date of content, try searching the web for "web server cache control".  For example, I found information about configuring the Apache web server at http://www.websiteoptimization.com/speed/tweak/cache/ and information about Microsoft's IIS web server at http://www.iis.net/ConfigReference/system.webServer/staticContent/clientCache.

    I hope this helps.


    Eric Stollnitz, Interactive Visual Media Group, Microsoft Research
    Monday, August 1, 2011 6:06 PM

All replies

  • Hi Francois,

    Yes, that's right, HDView is using the browser cache, plus it caches tiles in memory on its own.  Clearing your browser cache needs to be coupled with purging HDView's memory cache, but unfortunately there's no mechanism to do that.  Panning around a lot will bring in new tiles and flush out the old ones.

    --Howard

     

    Monday, August 1, 2011 4:59 PM
  • Francois,

    If you only control the client side, you'd need to reload the web page after clearing the browser cache in order to guarantee that HD View doesn't display any cached tiles.  However, if you also control the server side, there are ways to set the expiration date of content so that the browser will not cache it, or will only cache it for a specified time period.  If you can configure the web server so that the image tiles expire immediately, then every time you reload the web page, HD View would load fresh tiles and you would not need to clear the browser cache.  You could even edit the web page that displays the HD View control and add some JavaScript code that forces the web page to reload every 30 minutes to get the latest tiles (assuming the old tiles have expired from the browser cache).

    For more information on how web servers tell browsers the expiration date of content, try searching the web for "web server cache control".  For example, I found information about configuring the Apache web server at http://www.websiteoptimization.com/speed/tweak/cache/ and information about Microsoft's IIS web server at http://www.iis.net/ConfigReference/system.webServer/staticContent/clientCache.

    I hope this helps.


    Eric Stollnitz, Interactive Visual Media Group, Microsoft Research
    Monday, August 1, 2011 6:06 PM