Taking over output in your special page
From mediawiki.org
Normally your Special page will queue up some HTML and/or wikitext output via $wgOut, which will take care of actual HTML output and skinning at the end of the request.
Sometimes though you want to output things directly, such as to export a custom XML type, data feed, or binary download. It's not too hard to do, but it's not super-obvious either... Here's some example bits snipped from Special:Export:
In your SpecialPage class's execute() method:
// Disable the regular OutputPage stuff -- we're taking over output! $wgOut->disable(); // Cancel output buffering and gzipping if set // You might need this if you're creating HUGE output, otherwise skip it //wfResetOutputBuffers(); // Set your content type... this can XML or binary or whatever you need. header( "Content-type: application/xml; charset=utf-8" ); // If you want to force browsers to download instead of showing XML inline you can do something like this: // Provide a sane filename suggestion $filename = urlencode( $wgSitename . '-' . wfTimestampNow() . '.xml' ); header( "Content-disposition: attachment;filename={$filename}" ); // Now you can output data directly with 'print', 'echo', etc. print "<xml><hello to='world'/></xml>";