Re: [sipcore] Draft new version: draft-holmberg-sipcore-proxy-feature

[Christer Holmberg <[e-mail]>]

Hi,

In my opinion the big difference (a little simplified) from when we had the service-id discussion is the following:

- The service-id is used by the sender to REQUEST the receiver to do something. If the receiver doesn't do it (e.g. because it doesn't understand the service-id) the sender might not get the assumed result in the particular dialog.

- The feature tag is used by the sender to INFORM the receiver about a feature that it supports. It's up to the receiver to determine whether it wants to use that information for anything. And, if it doesn't (or, it doesn't even understand the meaning of the feature tag), nothing will go wrong in the particular dialog, because the sender didn't assume the receiver to do anything.

sip.instance is a very good example of informing. The sender doesn't really expect the receiver to do anything with the information (unless there is an associated option-tag), but the receiver MAY use it e.g. to later do a call transfer.
 
So, in my opinion, THAT is the separation we need to do, rather than arguing about terminology. 

(We know that people have changed "service" to "feature" in their drafts simply because of "political reasons", so I think it's really worthless trying to categorize)

Regards,

Christer






________________________________________
From: Paul Kyzivat [[e-mail]]
Sent: Thursday, January 27, 2011 7:57 PM
To: Christer Holmberg
Cc: Adam Roach; [e-mail]; [e-mail]
Subject: Re: [sipcore]  Draft   new     version:        draft-holmberg-sipcore-proxy-feature

On 1/27/2011 12:26 PM, Christer Holmberg wrote:
>
> Hi,
>
>> IMO the key differences are:
>>
>> - the definition must be publicly available
>> - capabilities/feature-tags should be orthogonal
>>
>> (And of course it is impossible to verify orthogonality
>> without the definitions being available.)
>
> As far as I know, all 3GPP specifications are publicly available.

I wasn't trying to imply that they are not, just putting a stake in the
ground generally.

The orthogonality also ties into the quote Adam cited. I had forgotten
exactly how that was stated. It goes further.

        Thanks,
        Paul