[hybi] Compression spec decoupling

[Takeshi Yoshino <[e-mail]>]

As the target data is close, I'd like to list options with concrete
examples and call for opinions to settle this topic.

See also this thread:
http://www.ietf.org/mail-archive/web/hybi/current/msg09469.html

We have two options.
(I saw slight objection to add a new handshake header to pass
algorithm parameter in f2f meeting)

a) One per-frame compression extension for all compression algorithm

draft-ietf-hybi-websocket-perframe-compression defines
- an extension "perframe-compress" and how it frames data including usage
of RSV1
- an extension parameter "algorithm" and its format
- an algorithm parameter "deflate" and how it transforms data

RSV1 is given to perframe-compress extension. It might make incompatible
extension checking easier.

There something does "per-frame compression" but needs framing beyond what
we define in this spec might come in the future. Then, we need to choose
either of break this 1:1 assignment or forbid it to use RSV1.

Example:
Sec-WebSocket-Extensions: perframe-compress; algorithm="foo;
foo-param1=123, bar; bar-param1=abc"; general-param1=xyz", ...

Example (with mux):
Sec-WebSocket-Extensions: perframe-compress; algorithm="... (algorithms for
pre-mux) ...", mux, perframe-compress; algorithm="... (algorithms for
post-mux) ..."

b) One extension for each per-frame compression algorithm

draft-ietf-hybi-websocket-perframe-compression defines
- a method how to frame data with per-frame compression including usage of
RSV1
- an extension "deflate-frame" which uses the framing method and how to
transforms data

RSV1 is given to any extension that does per-frame compression. Endpoints
need to sort out mutually exclusive extensions.

Any future per-frame compression extension may or may not refer to the
framing method defined in draft-ietf-hybi-websocket-perframe-compression.

Example:
Sec-WebSocket-Extensions: foo-compress; foo-param1=123, bar-compress;
bar-param-1=abc, ...

Example (with mux):
Sec-WebSocket-Extensions: ... (extensions for pre-mux) ...", mux, ...
(extensions for post-mux) ..."