Subject: [SPIRITS] Architecture Document?

From: Lawrence Conroy <[email-masked]>
Date: Wed, 29 Nov 2000 15:41:33 +0000

Hi Folks,

A few comments on the Architecture document that have been raised by 
a reference
in the recent PLMN location services doc.

The mobile doc refers to an Architecture document , version -01.
The architecture document I've seen seems to be at version -00.
To confuse things slightly, that architecture document has Lev's original title
(with version -01) on each page.

I guess this is the source of the confusion, but if not, then I'm commenting
on an out of date doc, and apologize. However, here goes...
------------
The Architecture (and the diagram it contains) doesn't seem to have 
changed in light of
the discussions in Pittsburgh (and before):

(i) It shows the "Subscribers Telephone" in the Internet (i.e. above 
the horizontal dashed line),
even though we aren't talking about Voice over IP phones.
(ii) It also shows a PINT Server *in* the Internet. This is not a 
good place for an Application
Level Gateway ->between<- the PSTN and the Internet. It should 
instead be on the border,
arguably level with the SPIRITS Client.
(iii) Similarly, the SPIRITS system has a proxy between the client 
and server, whilst the PINT
system doesn't.
(iv) Finally, the "Executive System" and the "Initiative System" have 
been replaced by the SCF
(with SSF connected via SS7).
These are *examples* of Executives and Initiatives, not the *only 
possibility*. Check back
through the PINT and SPIRITS meetings for statements to that effect.

As this diagram is now being reproduced in other drafts (notably the 
mobile services one),
please can this be fixed at last.

It appears that the original goal of symmetry and generality that I 
thought we had for PINT
and SPIRITS is less clear than it was; it should be easy to see 
whether something is a SPIRITS
or a PINT service, just by looking at the message sequences; 
apparently not. Hey ho.
------------
-- 
All the best, Lawrence
----------------------------------------
| Lawrence Conroy,    |50o55'15"N,1o24W|
| Roke Manor Research |     at home    |
|- [email-masked]  ---|+44 23 8023 5950|

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From: Igor Faynberg <[email-masked]>
Date: Wed, 29 Nov 2000 11:25:51 -0500

> the discussions in Pittsburgh (and before):

Well, the document was supposed to change in view of the discussion
on-line. We did NOT finish the Pittsburgh discussion at the meeting.And
even if we did, the meetings do NOT make decisions.

> even though we aren't talking about Voice over IP phones.

We could re-draw that, althought I really don't see how that could cause
a confusion. The document very clearly states that it has nothing to do
with Voice over IP.

> arguably level with the SPIRITS Client.

The PINT server is an Internet end-point. But if Lawrence re-drew the
picture to improve the visual statement, I would happily accept.

> and server, whilst the PINT

That is true. The role of the proxy is well described in the document to
explain why.

> (with SSF connected via SS7).

Actually, nothing has been replaced. We started not with the PINT model,
but with the SPIRITS model, in accordance with the SPIRITS charter. But
it is true that in PINT we would need a reference to the Executive
System; we could add text to that end.

> through the PINT and SPIRITS meetings for statements to that effect.

In PINT, yes, but in SPIRITS, no. These are NOT the examples, and the
SPIRITS charter makes a very clear statement to that effect. The
interface between the SPIRITS client and the SPIRITS proxy is precisely
the interface to carry the IN trigger information. For the more abstract
things, there is an interface between the SPIRITS proxy and SPIRITS
server, which is why Lev placed the SPIRITS proxy and PINT server on the
same level. Thus, the "Executive System" would need to be at the level
of SPIRITS Proxy.

> please can this be fixed at last.

We would need to understand WHAT needs to be fixed first.  After Lev has
published this diagram, at least seven months had passed, and the
document was considered stable even before Pittsburgh. 

> and SPIRITS is less clear than it was

I respectfully disagree. "Symmetry" perhaps was a goal, but it means
nothing to me without a specific context. We are not doing things for
the sake of symmetry, we are doing them to make things work.  As for
"generality," I believe the things ought to be specific, not general. We
had an Informational that clearly showed how things were implemented,
and Lev came up with the architecture that captured it.

But why am I speaking?  Because I am stuck with the work for now!
I was told that Lev is on a critical assignment right now and cannot get
involved, so I sort of picked up things for him for now with the
understanding that any change will be made for a solid technical reason.

>... it should be easy to see
> apparently not.

The architecture document does not address any message sequencing, so I
don't see how this argument applies here. But, actually, I don't
understand the issue.  If a service starts in the PSTN, it is SPIRITS;
if it starts in the Internet, it is PINT. 

Igor