Re: [hybi] Handling multiple compression method entries of the same extension

If this functionality is to be included I think 2-d is the best option.

I am mildly concerned about the increasing complexity of the perframe-compress extension handshake. Is this sort of negotiation common for compression in other protocols?

Peter Thorson

On May 11, 2012, at 0:55, Takeshi Yoshino <tyoshino@google.com> wrote:

> Hi,
> 
> I'm going to clarify whether multiple method descriptions with the same method name is allowed to be listed in the perframe-compress's method parameter or not.
> 
> The benefit of allowing multiple entries is that the client can offer the same extension with different parameter settings to try to use the best parameter both endpoints can agree.
> 
> There's also a problem with this. The client cannot identify which of the entries has been accepted by the remote endpoint.
> 
> Options we can take are:
> 
> ----
> 
> 1-a) disallow use of multiple entries
> 
> 2-a) tag requested methods
> Request:
> perframe-compress: method="deflate; id=0; foo=200, deflate; id=1; foo=100, deflate; id=2; foo=0"
> Response:
> perframe-compress: method="deflate; id=1; bar=3.14"
> 
> 2-b) put "rejected" that means the method placed at the corresponding position in the requested-method-list has been rejected.
> Request:
> perframe-compress: method="deflate; foo=200, deflate; foo=100, deflate; foo=0"
> Response:
> perframe-compress: method="rejected, deflate; bar=3.14, rejected"
> 
> 2-c) send back not a method description but the index of the description to accept and server-side parameter
> Request:
> perframe-compress: method="deflate; foo=200, deflate; foo=100, deflate; foo=0"
> Response:
> perframe-compress: accept=1; bar=3.14
> 
> 2-d) ack the requested parameters by echoing them back to make the accepted-method-desc self-contained (describing all negotiated parameters)
> Request:
> perframe-compress: method="deflate; foo=200, deflate; foo=100, deflate; foo=0"
> Response:
> perframe-compress: method="deflate; foo=100; bar=3.14"
> 
> ----
> 
> My preference is 2-d). I'll rename max_window_bits and no_context_takeover by prefixing them.
> 
> What do you think?
> 
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