Subject: [sipcore] location conveyance and error "code" parameter

From: "Thomson, Martin" <[email-masked]>
Date: Fri, 16 Jul 2010 14:22:09 +0800

Two related non-ABNF questions about the "code" parameter in the Geolocation-Error header that I thought would be better separated:

1. Why is called "code" if it contains text?  The actual code (location-error-code) is the 3 digit value.  It might be confusing talking about the "geolocation error code".  Would it be better named to "message"?

2. If I understand correctly, the "code" parameter has a value that is fixed based on the 3 digit code.  A fixed message doesn't add any value [1].  If a human readable message is required, then allowing for arbitrary content would be more likely to be useful.
The existing strings are useful as titles for the codes, but that's all.

--Martin

[1] See discussion in a recent meeting on this subject.

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From: "James M. Polk" <[email-masked]>
Date: Fri, 16 Jul 2010 02:03:12 -0500

Martin

in-line

At 01:22 AM 7/16/2010, Thomson, Martin wrote:
>Two related non-ABNF questions about the "code" parameter in the 
>Geolocation-Error header that I thought would be better separated:
>
>1. Why is called "code" if it contains text?  The actual code 
>(location-error-code) is the 3 digit value.  It might be confusing 
>talking about the "geolocation error code".  Would it be better 
>named to "message"?

I think "message" would be confusing as it would be different than 
the SIP response it was carried in (a 424 (Bad Location Information) 
or something else). If code is completely appalling to folks, then I 
think "value" could be used instead, but not "message".

>2. If I understand correctly, the "code" parameter has a value that 
>is fixed based on the 3 digit code.  A fixed message doesn't add any 
>value [1].  If a human readable message is required, then allowing 
>for arbitrary content would be more likely to be useful.

I'm not sure I agree on this one. Most everyone knows what a 404 "Not 
Found" means; as a computer (rather than human) is returning your 
request because of what the string says. i.e., "Not Found".  This 
make the meaning more final to humans much of the time. Anyone who's 
browsed has received a 404 (with the text too) and understands it.

thus, if I understand what you are suggesting (and I may not) - I 
think both the 3 digit value and the string should be present as much 
as possible. That said, the string is optional, the 3 digit value, or 
code, is not - for a GeolocationError at least.

Please let me know if I've misunderstood your point #2.

James

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From: "Thomson, Martin" <[email-masked]>
Date: Mon, 19 Jul 2010 08:33:58 +0800

Hi James,

> think "value" could be used instead, but not "message".

I don't mind what the parameter is called.  "code" is confusing, that's all.  "text" is another alternative to consider.  "value" implies that the content of the parameter is valuable in some manner, it seems a little disingenuous (see below).

> browsed has received a 404 (with the text too) and understands it.

The human value of the string "Not found" is debatable.  If you don't speak English, then it is even less so.  After all, a browser is capable of generating more appropriate message text.

The code (404) contains all the required information.  From this, a user agent (or server) can generate a message that is better suited to their audience.  For instance:

  "The requested URL <url> was not found on this server."

Fixed text (Not found) is redundant.  Variable text can be useful in providing diagnostic information. 

> Please let me know if I've misunderstood your point #2.

If the following is possible, then we have no problem:

  200 OK
  ...
  Geolocation-Error: 301;code="Please allow me to redistribute your location."

--Martin

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From: "James M. Polk" <[email-masked]>
Date: Sun, 25 Jul 2010 06:00:18 -0500

>think "value" could be used instead, but not "message".

BTW - there are SIP response codes, Reason header cause values and 
Warning header codes

code and cause are used in SIP header values.

I'm ok with either

James

>>is fixed based on the 3 digit code.  A fixed message doesn't add 
>>any value [1].  If a human readable message is required, then 
>>allowing for arbitrary content would be more likely to be useful.
>I'm not sure I agree on this one. Most everyone knows what a 404 
>"Not Found" means; as a computer (rather than human) is returning 
>your request because of what the string says. i.e., "Not 
>Found".  This make the meaning more final to humans much of the 
>time. Anyone who's browsed has received a 404 (with the text too) 
>and understands it.
>
>think both the 3 digit value and the string should be present as 
>much as possible. That said, the string is optional, the 3 digit 
>value, or code, is not - for a GeolocationError at least.
>

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From: "James M. Polk" <[email-masked]>
Date: Sun, 25 Jul 2010 06:12:20 -0500

At 07:33 PM 7/18/2010, Thomson, Martin wrote:
>I don't mind what the parameter is called.  "code" is confusing, 
>that's all.  "text" is another alternative to consider.  "value" 
>implies that the content of the parameter is valuable in some 
>manner, it seems a little disingenuous (see below).
>
>The human value of the string "Not found" is debatable.  If you 
>don't speak English, then it is even less so.  After all, a browser 
>is capable of generating more appropriate message text.
>
>The code (404) contains all the required information.  From this, a 
>user agent (or server) can generate a message that is better suited 
>to their audience.  For instance:
>

isn't this exactly what we allow?

James

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From: "Thomson, Martin" <[email-masked]>
Date: Sun, 25 Jul 2010 22:20:19 +0800

> isn't this exactly what we allow?

 I don't know.  The text sort-of implies that the text that you have provided (in this case " Permission To Retransmit Location Information to a Third Party") is the only permissible text.

If that's a misunderstanding on my part, then we're cool.  I'll be happy to provide clarifying text so that others don't come to the same (wrong) conclusions.

--Martin