Subject: [BLISS] BLISS problem statement draft

From: "Peter Musgrave" <[email-masked]>
Date: Wed, 18 Jul 2007 11:22:08 -0600

Hi Jonathan, 

In the motivation section you have:

   In some cases, these interoperability failures are the fault of poor
   implementations.  In other cases, they are purposeful failures, meant
   to ensure that third party equipment is not utilized in a vendor's
   solution.  

I think there is another major reason we are in "the confusion of
tongues" (nice turn of phrase BTW). It is simply that an implementing
company is typically developing a server or a specific UA and is trying
to provide some feature to the customer. The only thing under their
direct control is the part of the 'distributed state-machine' that
resides within their product. To release a feature in a timely way the
implementation will be tilted in favor of an implementation on that
product which makes only very basic assumptions about the other elements
in the 'distributed state machine'. 

In this case I don't see it as poor implementations or deliberate
failures - it simply stems from a desire to get stuff out the door - and
I think it will keep happening over and over again.

While I really want BLISS to succeed (since it's almost kinda funny that
after 20 SIPits things like park/pickup are still fair game for
discussion), I think the ambition expressed in your problem statement is
*very* difficult. Mandating a specific implementation (modulo some
details) may be ultimately more successful.  

Are you aware of any 'existence proofs' of efforts where a specification
has constrained behavior without detailing implementation and led to
successful interop?

I think the "Phase II" - Submit feature flows - is of substantial
benefit in its own right. There are many cases where I have developed a
flow for something only to find a much better one after its "too late" -
and a "Field Guide" to flows for common features *especially* with why
some flows crash-and-burn in some cases would be very useful - even if
we still end up with a confusion of tongues some of the more tortuous
dialects may be avoided.

Regards, 

Peter Musgrave

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