Using Content-Encoding and Content-Disposition together

The following question comes up when Content-Encoding and
Content-Disposition are used together in a message:

To which layer in the two-layer, ordered encoding model:

                entity-body := Content-Encoding( Content-Type( data ) )

of 7.2.1 (draft -08) does a suggested filename in Content-Disposition
apply?  As an example, let's take the gziped text format of the draft 
itself, available at
<http://www.w3.org/Protocols/HTTP/1.1/draft-ietf-http-v11-spec-08.txt.gz>.
Thanks by the way for providing it in this format, works great with Lynx.

This is currently being served with headers (among others)

  Content-Encoding: gzip
  Content-Type: text/plain

If one wanted to add a Content-Disposition header, should that be

  Content-Disposition: xxx; filename="draft-ietf-http-v11-spec-08.txt.gz"

or

  Content-Disposition: xxx; filename="draft-ietf-http-v11-spec-08.txt"

Current usage (typically larger files, which will be saved in
compressed form) suggests the first alternative.  If Content-Encoding
becomes more of an on-the-fly thing, the second alternative makes more
sense - especially if proxies can change the coding.  (In the second case
a client wishing to save to disk in compressed form would probably append
the ".gz" suffix to the suggested name, as required or "natural" for the
platform.)

Since this is a HTTP specific question which doesn't occur for mail,
the HTTP spec should probably say something about it.
It may become an impediment to implementing Content-Encoding in clients,
if different implementations choose different answers.  (for all I know
there may be today more widespread support for Content-Disposition than
for Content-Encoding in user agents.)

   Klaus

Received on Friday, 1 August 1997 23:01:36 UTC