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Robert,
Thx for speedy response. I have a
question again.
How a
same session is shared between 2 modules using an MSRP
layer?
My
understanding is same connection and same session can be shared between 2 or
more modules which are capable of sending MSRP
messages.
I have
2 user agents E1 & E2. E1 has 2 modules, Mod1 & Mod2 (both in same
process) using MSRP layer.
Mod1
establishes MSRP session with E2, MSRP URL as
msrp://mod1.example.com:7654/jshA7we;tcp
Then Mod1 has a chat session with E2.
Now Mod2 wants to use same connection & same MSRP session as
Mod1.
My understanding is Mod2 sends one more INVITE to E2, with MSRP
URL is SDP as
msrp://mod2.example.com:7654/jshA7we;tcp
here
the port and the session id is same as that was for Mod1.
Is
this the way one shares an existing session?
Please
clarify.
Thanks
& Regards,
Srinath
responses inline
On Jan 17, 2006, at 2:30 AM, Srinath.H.N wrote:
Hi
All,
I have 2 questions
regarding recent MSRP draft released.
1) In the latest
draft (draft-ietf-simple-message-sessions-13) there is a change
when compared to the previous draft numbered 12.
In section 5.1
the last but one paragraph states as given below.
.......... The ability to interrupt messages allows multiple sessions to share a
TCP connection, and for large messages
to
be sent efficiently while not blocking other messages that share the same
connection, or even the same MSRP
session.
Any
chunk that is larger than 2048 octets MUST be interruptible.
....................................
The
colored text is the change. Can you please explain what "MSRP session" here
means?
Does that mean the session which is established using SIP or it
refers to the media session that follows the SIP
signalling?
MSRP is media. An MSRP
session is set up using SIP the same way an RTP session is set up
using SIP. When you say "the session which is established using SIP"
above, I think you must
mean dialog (or dialog usage). Otherwise, both sides of your "or" refer
to exactly the same thing.
2) multiple sessions can share a same TCP
connection.
So if we have 2 applications listening on the default
port, say 6000 ( which might be standardized later) and if we receive a
SEND request,
Please be precise with your terms. You will never have two applications
(in the different process
sense) listening on the same port. I think you mean two parts of your
code sharing an MSRP layer.
There will never be a default port for MSRP. There is no need for one,
the same way there is no
need for a default port for RTP. MSRP does not stand alone - an MSRP
session must be established
with a rendezvous protocol. Right now, that's only SIP.
how
do we arbitrate among the applications?
You use the identifier that
arrives in the To-Path (you provided this in the SDP you used to set
up the session - you will use a unique identifier here for each
session you set up). Look, for example,
at the bottom of page 12 (of message-sessions-12), and scan for the
role of the To-Path in general.
There should be some protocol specific parameter based on which
the MSRP stack can give the event to an
application.
How
do we do that in MSRP? see
above.
Please help me in finding answers to the above
questions.
Thanks & Regards,
Srinath.
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