Subject: [Ecrit] [issue2] Is it allowed to specify civic and geospatial info into the query?

From: Hannes Tschofenig <[email-masked]>
Date: Mon, 05 Jun 2006 13:28:08 +0000

Hannes Tschofenig <[email-masked]> added the comment:

Currently, a query (LosT client to LoST server) can either contain civic OR 
geospatial location information. It cannot contain both. Would it be useful to 
allow both to be included in the query?

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nosy: +ecrit
status: unread -> chatting

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From: "Brian Rosen" <[email-masked]>
Date: Mon, 5 Jun 2006 09:42:57 -0400

I would say no.  One of the ideas I think we have agreed to is that the LoST
server is not in a position to decide what to do if more than one location
is sent.  The geo and the civic may (probably will) be somewhat different,
and if the difference causes a difference in route, the LoST server can't
decide what to do.

The client can always send two queries, one with the geo and one with the
civic and decide what to do if the results are different.

Brian

-----Original Message-----
From: Hannes Tschofenig [mailto:[email-masked]] 
Sent: Monday, June 05, 2006 9:28 AM
To: [email-masked]
Subject: [Ecrit] [issue2] Is it allowed to specify civic and geospatial
infointo the query?

Currently, a query (LosT client to LoST server) can either contain civic OR 
geospatial location information. It cannot contain both. Would it be useful
to 
allow both to be included in the query?

----------
nosy: +ecrit

---

From: Henning Schulzrinne <[email-masked]>
Date: Mon, 5 Jun 2006 09:45:11 -0400

The problem with having both is that the answers may differ, thus  
creating a new error condition. As far as I can tell, the same result  
can be achieved by querying sequentially, starting with whatever  
location information the querier deems best and falling back to the  
other if needed.

Since the querier can issue two queries in parallel if time is  
important, there is no real performance hit, except for some modest  
additional packet overhead.

Thus, in the spirit of keeping things simple and predictable, I'd  
say: no.

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From: Andrew Newton <[email-masked]>
Date: Mon, 5 Jun 2006 10:25:57 -0400

Not that I disagree with what you are saying, but wouldn't we want to  
put the decision as to which is the best PSAP to call based on the  
two sets of information in the hands of the LoST server and not at  
the client?

Also, in the scenario you have given, how does the seeker determine  
whether the civic or geo location is best?

-andy

On Jun 5, 2006, at 9:45 AM, Henning Schulzrinne wrote:

> creating a new error condition. As far as I can tell, the same  
> result can be achieved by querying sequentially, starting with  
> whatever location information the querier deems best and falling  
> back to the other if needed.
>

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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 05 Jun 2006 14:53:30 -0400

Andrew Newton wrote:
> put the decision as to which is the best PSAP to call based on the two 
> sets of information in the hands of the LoST server and not at the client?
> 

Hard to say in general. There might be reasons that the client has a 
preference or knows which type of information to trust more:

- GPS data has not been updated in a while (lost satellite contact) or 
has a high error margin, but civic data (e.g., via LLDP) is more recent.

vs.

- GPS data is recent, but maybe the system also has some geo-mapped data.

vs.

- End system uses some kind of Skyhook-like 802.11 service, which has 
moderate accuracy and has some civic "beacon" information that's not as 
recent.

In all of these dual-information cases, I don't see how anybody except 
the seeker can make any determination which type of information is 
better, more accurate, more recent, etc.

There's obviously a different scenario when for some reason, the LoST 
server only knows a mapping for either geo or civic, but not both. In 
that case, an error message such as "No resolution for civic; try geo" 
(obviously, an error code, not just a string) might be helpful.

In practice, I suspect that the server will have the same information 
for both geo and civic; that seems to be the common case today where 
both are available.

Henning

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From: Andrew Newton <[email-masked]>
Date: Mon, 5 Jun 2006 15:11:05 -0400

On Jun 5, 2006, at 2:53 PM, Henning Schulzrinne wrote:
> In all of these dual-information cases, I don't see how anybody  
> except the seeker can make any determination which type of  
> information is better, more accurate, more recent, etc.

Would we want the seeker to determine which information it feels is  
best to provide to the PSAP?  I've always heard that the answer would  
be no: provide both to the PSAP.  So why then would we not provide  
the same information when determining which PSAP to contact?

-andy

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From: Henning Schulzrinne <[email-masked]>
Date: Mon, 05 Jun 2006 15:55:15 -0400

At the PSAP, we have a human that can look at this information and make 
decisions (and maybe even ask if there's a discrepancy). That seems a 
stretch for the LoST server.

Andrew Newton wrote:
> Would we want the seeker to determine which information it feels is best 
> to provide to the PSAP?  I've always heard that the answer would be no: 
> provide both to the PSAP.  So why then would we not provide the same 
> information when determining which PSAP to contact?
> 
> -andy

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From: "Brian Rosen" <[email-masked]>
Date: Mon, 5 Jun 2006 16:32:14 -0400

I think this is the issue.  There is no guidance we can give the server to
tell it how to resolve what to do when  both locations are valid but the URI
for the geo does match the URI for the civic.

This happens a lot when you are near boundaries because the precision and
accuracy of the two methods differ.

I think you pick ONE and use it.

Even if you send more than one along, the PSAP has to know which one you
used to route.  It's going to continue to use that until a human says
otherwise.

Brian

-----Original Message-----
From: Henning Schulzrinne [mailto:[email-masked]] 
Sent: Monday, June 05, 2006 3:55 PM
To: Andrew Newton
Cc: [email-masked]
Subject: Re: [Ecrit] [issue2] Is it allowed to specify civic and
geospatialinfo into the query?

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From: Hannes Tschofenig <[email-masked]>
Date: Mon, 05 Jun 2006 22:38:56 +0200

It seems that we closed this issue.

Everyone seems to be in favor for a civic OR geospatial.
Extensions possible for future applications.

Ciao
Hannes