[Zope] how to download big files using zope?

[Yuppie]

Hi!

I have some big files (about 500 MB) in the filesystem on the server and 
want to make them downloadable.

I could do something like this, but it loads the file into memory:

<code>
def manage_download(self, REQUEST):
     myfile = open('myfile.bin', 'rb')
     filestring = myfile.read()
     myfile.close()
     REQUEST.RESPONSE.setHeader('Content-type', 'application/data')
     REQUEST.RESPONSE.setHeader('Content-Disposition',
                                'inline;filename=myfile.bin')
     return filestring
</code>

Is there a way to just pass the file through? Without loading it in a 
string or in the ZODB?

Any hints are welcome.

TIA,
Yuppie