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Asked: 2026-05-19T00:58:12+00:00

Basic Requirements I have a SL app that can be run in-browser or out-of-browser.

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Basic Requirements

I have a SL app that can be run in-browser or out-of-browser. I want the browser to:

  • Cache the xap file
  • Load the xap from the cache if it has not changed or re-download it if it has changed.

More details

Setting a future expires header obviously solves the caching problem but then I cannot force the user to download the latest version. Normally I would just add a querystring to the url (eg url?v=1) but I cannot do this as this breaks the out-of-browser functionality. eg the app thinks it is not installed when in fact it is.

no cache

If I set Cache-Control to no-cache, Chrome and Firefox correctly send a request to the server for the xap but use the cache if a 304 is returned. IE8 just downloads the file again as does Safari.

must-revalidate

Setting Cache-Control to must-revalidate again works correctly in Chrome and Firefox but Safari always downloads the xap again while IE8 always uses the cache.

How do I set this up to work as described at the start of this question?

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1 Answer

  1. Editorial Team

    I’m not sure that the Chrome/Firefox is strictly “correct”, you have after all not told the browser that it should cache the content or even that the content is cacheable.

    Instead of no-cache try “Cache-Control: max-age=15” instead. See if that convinces IE that it ought cache the content despite its large size (which is why its not caching it originally).

    For OOB install use the Application object’s CheckAndDownloadUpdateAsync method. Note you need to inform the user to restart the app once an update has been downloaded.

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