[TYPO3] Write output to static file

[David Krüsemann]

Hi list,

in some cases, I want TYPO3 to write full page output into a static file 
(e.g. xml, html) using

file_put_contents($filename,$????);

in my extension. Already had a look in tslib_fe without any results.
Does anybody know how/where to access page generation for this purpose??

Any help appreciated,
David