On 10/30/14 5:23 PM, Dale R. Worley wrote:
From: Paul Kyzivat <pkyzi...@alum.mit.edu>
I disagree here. UA B would be irresponsible if it created an INVITE
including a header field that it doesn't understand.
Why would it be irresponsible?
It's not UA B that's deciding to produce the INVITE, it's the element
that sends the REFER to UA B that is deciding that Replaces is needed.
If UA B understands Replaces, then it will presumably know that it is
safe to include it in the INVITE - that it is harmless.
But if UA B *doesn't* understand the header, then it doesn't understand
what the implications are of including it. And the resulting INVITE is
from B - it will be responsible for whatever happens. Doing that is
irresponsible.
For instance, what if a Geolocation header was embedded in the URI, and
UA B didn't understand that header. This could result in UA B making a
call with a fraudulent location. That could potentially be used for lots
of ulterior purposes.
A similar but more extreme example of that is a 'method=" parameter in
the Refer-to URI. If the recipient doesn't understand the method named
it would be irresponsible (insane) for it to create a request with that
name.
Thanks,
Paul
And that element is responsible for deciding to what to do if
destination of the INVITE does not understand Replaces -- ignore it
(the default) or reject the INVITE (by also putting
"&Require=replaces" into the Refer-To URI).
Dale
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