crossdomain.xml prevent caching

Question

After changing domain name where flash application being hosted I should change crossdomain.xml file. That crossdomain.xml is hosted on api-server, which is used by flash application. I see that flash uses crossdomain.xml from browser's cache. Is there any trick to make flash to not get crossdomain.xml from cache? Maybe there is any parameter, that I can pass to flash during it's call in object tag?

Answer 1

Annoying issue - no doubt.

First of all: I like Caching - as long as I'm in control. This is, how I gain control over crossdomain.xml caching:

Let's say, we have a flash app that requires some input from a different server. In my case we have this configured as a flashvar dataSrc=http://www.company.com/data/calendar.xml

So flash is looking for www.company.com/crossdomain.xml ... which is loaded once and than taken from users browser cache until he manually flushes it.

The solution is in changing the subdomain the crossdomain.xml ist taken from:

Make sure, that for example(!) noCache.company.com/ points to company.com's documentRoot. Flashvar is modified to dataSrc=http://noCache.company.com/data/calendar.xml. In fact, you're addressing the same file as before.

Flash is looking for noCache.company.com/crossdomain.xml which will be taken from the Server now because there is no cached file for that uri.

It's up to your fantasy... if you allow subdomains like noCache_{numeric_value}, you could easily handle your own TTL by accessing http://noCache_{week_of_year}.company.com/data/calendar.xml ...

You can as well increment that numeric value each time crossdomain.xml has changed.

Answer 2

Use following apache directives to specify caching policy for the file:

<Directory /var/www/mysite>
  <FilesMatch "crossdomain.xml">
    Header set Cache-Control "max-age=86400, public, must-revalidate" 
  </FilesMatch>
</Directory>