streaming dynamic downloads?

[jeff emminger]

I have a php app running through fastcgi, and there's a page where I
stream out a file for the user to download:

	$output = dynamically_generated_content();
	header("Content-type: application/octet-stream");
	header("Content-disposition: attachment; filename=somefile.xml");
	echo $output;

This works fine in apache, but in nginx all I get is a zero-size file
called 'somefile' (no extension)

Is there a way to make this work?  The file is generated on the fly.

Thanks,
Jeff