Subject: Re: [Sipping] Drafts on exploders

From: Gonzalo Camarillo <[email-masked]>
Date: Fri, 13 Feb 2004 11:38:53 +0200

Hello,

> Why do you need a heavy-weight light B2BUA for "exploding". 

Do you mean light *or* heavy-weight?

In any case, you do not want to use a proxy because the services these 
exploders provide (e.g., conferencing) are provided by B2BUAs, not by 
proxies.

Gonzalo

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From: "Banibrata Dutta" <[email-masked]>
Date: Fri, 13 Feb 2004 15:33:46 +0530

Hi Gonzalo,

  I am sorry, I meant "heavy-weight" only. Okay, isn't then exploder
itself a service, but yes it would become a feature they may be used
by several services. Confercing is then just another service that uses
the exploder feature, right?

  Won't it be better to take that responsibility out of a B2BUA and
put it in the core network (in the proxies) s.t. the explosion happens
where it is needed? Let me explain my view as follows:-

there are 2 ways:-

1) A single To: header which explodes to multiple INVITES (or other
   method messages).
2) A single INVITE with multiple To: headers which is understood by
   a router and split off into multiple INVITE's with single To:
   headers.

in the first case the exploding proxy (or entity) needs access to a
explosion database (i.e. group-name -> list of members). this "may be"
achieved by DNS mechanisms (i am not even close to being a DNS
expert, but i think that it can be done, the same way SOS URI's
are transformed into actual ERS/PCAP #s).

in the second case the exploding proxy doesn't need a explosion database
and the original INVITE anyway had all the info needed to split it off
into multiple INVITEs with single To: headers. 

with these approaches the benefit of "localization" of explosion can be 
used, i.e. the explosion happens as late as possible, leading to the
minimum # of messages in the network, i.e. multiple exploder proxies
would exist in the network and it may so happen that the orginal
invite with 10 To: headers go split into 2 INVITES with 6 and 4 To:
headers respectively at an exploder proxy, and then the INVITE with
6 To:s got split into 2 with 3 To:s each and so on. this way the
explosion is "Just-In-Time" and minimal.

regards,
banibrata dutta.

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] 
> On Behalf Of Gonzalo Camarillo
> Sent: Friday, February 13, 2004 3:09 PM
> To: Banibrata Dutta
> Cc: 'sipping'
> Subject: Re: [Sipping] Drafts on exploders
> 
> 
> Hello,
> 
> This communication is confidential and intended solely for 
> the addressee(s). Any unauthorized review, use, disclosure or 
> distribution is prohibited. If you believe this message has 
> been sent to you in error, please notify the sender by 
> replying to this transmission and delete the message without 
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> 
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> 
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> sip Use [email-masked] for new developments of core SIP
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---

From: Gonzalo Camarillo <[email-masked]>
Date: Fri, 13 Feb 2004 12:22:31 +0200

Banibrata,

The services we intend to provide using exploders are implemented using 
B2BUAs. If the services you have in mind can be implemented using only 
proxies, you do not need to use the mechanisms described in these drafts.

Thanks,

Gonzalo

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From: Michael Hammer <[email-masked]>
Date: Fri, 13 Feb 2004 10:20:31 -0500

I am a little leery of a proxy-based solution, based on the experiences 
with early media.  In essence, the middleman initiates the INVITE at the 
front end of a dialog then expects the UAC to handle who knows how many 
responses that return to it.  For connectionless operations it might work, 
but for connection-oriented operations, it can easily scale beyond the 
capability of the UAC to handle it.  Hopefully, this will be more elegant 
than early media.

Mike