Subject: [Sip] questions about drat-bjorkner-serviceroute-00

From: Timothy SOETENS <[email-masked]>
Date: Thu, 13 Sep 2001 10:23:39 +0200

Hi All,

I have some questions regarding the draft
draft-bjorkner-serviceroute-00.txt.

I think it is a good thing to route requests according to the service a
user is subscribed for, but still I am confused in how the service-route
header is used.

1. "The service-route header should only be inserted in the first
request in a call leg." (4.1, page 4) Is it not possible that you first
contact the callee before deciding on which service to use?

2. "If a request contians both route headers and service-route headers
the route headers MUST be used for request routing." (4.1, page 5)
Indeed, if the route headers are used for request routing, it is not
useful to insert service-route headers in the subsequent requests.
However, I have the feeling that service-route headers can be useful in
subsequent requests. 

Comments?

Thanks,
Tim.
-- 
Timothy Soetens
_________________________________________

From the Network Strategy Group @ Alcatel

Tel. +32-3-240.42.11
Fax  +32-3-240.48.88

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---

From: Henrik Gustafsson <[email-masked]>
Date: Thu, 13 Sep 2001 11:31:25 +0200

The service route is actually a loose route and the chain of service 
routes could
be considered as a chain of outbound proxies. We didn't like initial 
routing
and filtering services to be visited for a all following request, that 
is the reason
we stated a service-route SHOULD only be inserted in a initial request. 
If a
service needs to keep the call state, you should add a record-route, 
like you do
today.

Actually there is an error in the draft, the service route must also be 
added to
the CANCEL.

If a message contains both route-headers and service-route-headers, it is a
result of an error and the damage is minimized by just go for the route.

/Henrik Gustafsson

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From: Timothy SOETENS <[email-masked]>
Date: Thu, 13 Sep 2001 11:51:42 +0200

> service needs to keep the call state, you should add a record-route,
So the chain of service-route headers is actually a set of application
servers in the originating domain, each responsible for a different
server?
> result of an error and the damage is minimized by just go for the route.
I think this should be repeated in section 4.2. As the text is stated
now, section 4.2 says to go for the service-route header, at least that
s how I interpreted it.

Tel. +32-3-240.42.11
Fax  +32-3-240.48.88

---

From: Henrik Gustafsson <[email-masked]>
Date: Thu, 13 Sep 2001 14:05:02 +0200

>servers in the originating domain, each responsible for a different
Yes, that's true. I think it is important to point at that the 
service-route
is not the ideal service compositioning mechanism, it is just one
possible tool.

This is also related to the currently very active loose-routing thread.
I belive adding complexity to the existing route header is worse than
adding complexity to the protocol with a new relative simple header.

>now, section 4.2 says to go for the service-route header, at least that
Yes, it is somewhat unclear. Now it is described at the end of 4.1.

/Henrik