[sr-dev] Your opinion about presence subscription blocking actions

[Daniel-Constantin Mierla]

Hi Inaki,

On 02/18/2010 06:37 PM, Iñaki Baz Castillo wrote:
> Hi, I'm dealing with presence right now. I've read full OMA and RCS
> specifications/proposals/guidelines for presence and XCAP but I don't feel
> comfortable with some parts of them.
>
> So let me to explain the question (it involves the sr/kamailio presence module
> behavior for a future re-design in which I want to participate):
>
> In presence/XCAP/XDM there are three ways bob can deny alice to see his
> presence status (by modifying the XCAP documents according):
>
> 1) Ignore alice's request. This is, bob doesn't "allow" neither "blocks"
> alice, so alice just gets the first NOTIFY from the server with:
>    Subscription-Status: pending
> After some long time the server will send:
>    Subscription-Status: terminated ; reason=expired
>
> 2) Block alice by invoking a "block" action. This means that alice receives a
> NOTIFY from the server with:
>    Subscription-Status: terminated; reason=rejected
> This is: alice *knows* that she has been explicitely blocked by bob.
>
> 3) Polite-block alice by invoking "polite-block" action. In this way the
> presence server generates a spoofed NOTIFY for alice containing "offline"
> information but the header:
>    Subscription-Status: active
> This is: alice *things* she has been allowed by bob and bob it's offline right
> now (not true).
>
>
> Well, in real IM/presence world (MSN, Skype, XMPP, Yahoo...) option 2 doesn't
> exist, am I right? This is, if you block an user he doesn't know that you have
> blocked him. Instead just options 1 or 3 are used (and in some networks just
> option 1).
>
> Do you see any advantage in point 2? Personally I don't see it and it just
> introduces too much complexity for presence/XCAP/XDM client developers.
>    

I think two won't be much useful. Sending reject to user won't look 
polite :-). 1) looks good from my point of view, just letting it to 
expire without keep notifying presentity about new watcher. Also 3) is 
not very bad, but gives the impression that subscription request has 
been accepted, therefore some will get it as "that guy is friend with me 
right now".

Not sure how currently is handled by other IM when you do "deny" for 
presence subscription requests. I hope is not that tough :-) -- using 
gmail/yahoo/... email opens you to a lot potential subscriptions that 
have to be denied.

Cheers,
Daniel

> I would appreciate your opinnions about it.
> Thanks.
>
>
>    

-- 
Daniel-Constantin Mierla
SIP Server Professional Solutions
* http://www.asipto.com/