Subject: RE: [Sipping] More discussion of service-route draft

From: "Smith David G. (Adastral Park)" <[email-masked]>
Date: Wed, 21 Nov 2001 10:19:14 -0000

Hi Dean,

This is the first time I have seen this proposal. It looks a good approach
to me. 

One of the problems we have in mobile networks where services are
distributed across two or more application servers is how to resolve service
interactions. For example, the first application server may modify the
request URI and the second application server in the chain needs to know
that the first application server may have modified the request URI. The
fallback solution is to resolve service interactions when services are
provisioned, but this can be limit the scope of services. Some kind of
dynamic solution may be more useful.

One possibility is that the Service-Route header could perhaps optionally
include a 'history' containing a list of all of the application servers that
have handled the request and the sequence of handling (i.e. the chain). The
last application server in the chain could remove the 'history' as it would
no longer be needed.

Has the issue of service interaction been discussed in the context of this
memo?

Have I overlooked something in the current proposal?

Thanks,

David G. Smith

-----Original Message-----
From: Dean Willis [mailto:[email-masked]]
Sent: 20 November 2001 21:47
To: Sipping (E-mail)
Subject: [Sipping] More discussion of service-route draft

The service-route draft:

http://search.ietf.org/internet-drafts/draft-bjorkner-sip-serviceroute-00.tx
t

is a fairly complete writeup of one of the two loose-routing approaches we
came up with during the ad-hoc in London. The other suggestion from London
was a loose/strict modifiers on routes in the Route header, and there was an
older suggestion (from Alan Johnston) on using an maddr parameter on the
original request-URI.

"loose routing", as you may recall, is an attempt to meet the requirement of
delivering outbound services from a non-local proxy. For example, if I have
aspeed-dial service on my home proxy, I woulsd add the home proxy to my
servcie routem then send the request to my local outbound proxy. Before the
request gets delivered to the destination UA, it gets passed through my home
proxy, which might do something useful with it.

Anyhow, I think that there is a fairly clear path to using the service-route
proposal to meet the "how to get outbound services from the  home proxy"
requirement posed by 3GPP. In fact, I think it's a complete solution (or at
least very close) to that problem. There's the seperate problem of "how do I
find out what my home proxy is" that will have to be solved, but there are
three or four easy ways to do that and we've declared that a seperate
problem.

SO-- if you're involved in the 3GPP requirements work, please review the
afore mentioned draft, and if you either disagree with my "it's a fix"
assertion or wish to discuss it further, please do so. Also, please look it
over if you see a need to get outbound services from a home proxy in any
other sort of network (and I know you Comm/ASP people have this problem).

If this really does appar to be an effective solution, we can recommend it
up the the SIP group for detail consideration and implementation.

Thanks,

--
Dean Willis

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---

From: Dean Willis <[email-masked]>
Date: Wed, 21 Nov 2001 12:39:54 -0600

No, we haven't really gotten into service interaction in that sort of 
way. What you describe might be feasible. I suspect that we aren't going 
to know how to solve this sort of problem until we have more real world 
experience with application server environments. Doesn't hurt to think 
about it now, however!

--
Dean

Smith David G. (Adastral Park) wrote:

> Hi Dean,
>
> This is the first time I have seen this proposal. It looks a good 
> approach to me.
>
> distributed across two or more application servers is how to resolve 
> service interactions. For example, the first application server may 
> modify the request URI and the second application server in the chain 
> needs to know that the first application server may have modified the 
> request URI. The fallback solution is to resolve service interactions 
> when services are provisioned, but this can be limit the scope of 
> services. Some kind of dynamic solution may be more useful.
>
> One possibility is that the Service-Route header could perhaps 
> optionally include a 'history' containing a list of all of the 
> application servers that have handled the request and the sequence of 
> handling (i.e. the chain). The last application server in the chain 
> could remove the 'history' as it would no longer be needed.
>
> Has the issue of service interaction been discussed in the context of 
> this memo?
>
> From: Dean Willis [ mailto:[email-masked]]
> |
> |