Re: [hybi] hum #3: Message

[John Tamplin <[e-mail]>]

Ok, does this summarize the various positions regarding chunking and
lengths?


   - We want to have a length of the complete message when it is available
   to make buffer management simpler for the receiver
   - We want to be able to fragment messages to avoid extra buffering when
   the length of the entire message is not known up front, such as when sending
   dynamic content, compressing frames, etc.
   - We want to keep small frames having small overhead (though there is a
   limit on how much this matters given TCP/IP overhead)
   - We want to be able to send very large files in a single fragment so we
   can just hand it off to sendfile or equivalent

What about the following:

   - 1 bit - Initial fragment
   - 1 bit - Final fragment
   - 1 bit - reserved
   - 5 bits - opcode
   - 8 bits - short length
   - [if length = 255: 8 bytes - length]
   - [if Initial = 1 and Final = 0: 8 bytes - overall message length, with 0
   meaning "unknown"]
   - length bytes of payload

This could be extended with any of the extension or padding proposals out
there, just trying to get the basic idea of having initial/fragment bits
with an optional overall message length up for discussion.  The length could
be a variable-length integer as in v76 if you prefer, likewise for the
message length.

-- 
John A. Tamplin
Software Engineer (GWT), Google