Re: [Ecrit] Profiles (was: Consensus Call) - namespaces

[Andrew Newton <andy at hxr.us>]

On May 7, 2007, at 11:08 PM, Henning Schulzrinne wrote:
> I don't see what hints you can offer in this particular case. As  
> far as I know, we have not attributed any semantics to the ordering  
> of the elements. In general, I think it would be a bad idea to do  
> so, given that the schema considers both orderings equivalent.

Consider location profiles that are not yet defined.  Which one is this?

<gml:Point srsName="urn:ogc:def:crs:EPSG::4979">
  <gml:pos>-34.407 150.883</gml:pos>
</gml:Point>
<gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
  <gml:pos>
    -34.409 150.879
  </gml:pos>
  <gml:radius uom="urn:ogc:def:uom:EPSG::9001">
    850.24
  </gml:radius>
</gs:Circle>

Of course, if you are suggesting that future profiles the glue  
multiple elements together such as this would need to define their  
own schema to properly define them, then I consider that a fair  
design choice.  That does mean that the current method of 3825  
compound location defined in pdif-lo-profile would need a schema that  
wraps the gml and civicAddress.

Also, why would the LoST server need to identify profiles then?  It  
should use the same XML namespace mechanism.

> > Because, it would allow the sender to tell the server which  
> > profile it was sending.  Since neither of us seem to be advocating  
> > XML validation in this case, I be happy to compromise and say that  
> > senders do not have to include the profile identifier if they  
> > don't know it.  Is that workable?
>
> That's certainly a step in the right direction and probably the  
> minimum we need to do.
>
> However, including the label simply adds another error condition  
> that needs to be tested for. Now, the recipient has to verify  
> whether profile and content agree. The most likely consequence is  
> that most receivers will simply ignore the profile label. Such  
> 'latent' error conditions are not good, as a mislabeling sender  
> will likely not get an error message except from some small subset  
> of hyper-sensitive implementations - which may then only occur  
> during an emergency, when it's too late to fix.

There is no need to add another error condition.  Either the server  
knows what it is looking at or it doesn't.

> Or are you suggesting that the receiver treat this only as a hint  
> and ignore the label if it contradicts the XML?

Yes.

-andy

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