Re: [hybi] Frame size

[Greg Wilkins <[e-mail]>]

Mike Belshe wrote:
> Sorry - we're thinking of two different things for chunking.  I was
> thinking of chunking in terms of enabling multiplexing; but maybe I was
> off from the original poster.  Sorry if that is the case.

Mike,

I was not proposing Fragmentation for multiplexing.   I was
suggesting it for error handling (which I guess can be considered
multiplexing control frames).

The scenario that I'm concerned about is that we need
a way to handle too-large-handle messages.

Currently the specification says that the endpoint simply
closes the connection.  But that is unsatisfactory as the
reason for the close is not known and the too-large message
will just be resent.

So we need some way of sending an error status back, saying
that the message being sent is too-large.
But if our framing allows arbitrary large frames, then
we conditions in which there is no way of sending any error
state.

If both endpoints start sending a too-large-to-handle
message at the same time, then both endpoints will
want to send a too-large error frame.   But neither
will be able to because they are in the process of
sending a large frame.

This is not an insurmountable problem, and I'm sure
might be able to invent ways to abort frames and send
error state etc.  However, I believe that such error
handling in an unlimited frame-size environment will
be significantly more complex that a fragmentation
mechanism.

Fragmentation does not avoid the need for error
handling for too-large-to-handle messages.  But
by removing the possibility of too-large-to-handle
frames, it means we are more likely to be able to
simply send the error messages.


regards.

PS> Another alternative is to mandate a negotiation
of maximum message size in the handshake.
Or somebody can come up with a good simple design for
error handling with large (or unlimited) frames.