[Standards] Inconsistent Subscriptions in XMPP

Pedro Melo melo at simplicidade.org
Tue Feb 24 15:54:38 UTC 2009


Hi,

On Feb 24, 2009, at 12:49 AM, Pavel Simerda wrote:

> There are several cases when subscription databases in XMPP are
> inconsistent.
>
> You may view subscription information as a global distributed  
> database.
> Subscription state between two JIDs, for example a at A and b at B are  
> stored
> in two places at the same time. Servers A and B maintain their own
> copies of subscription state.

[....]

> What with the roster items that are inconsistent?
>
> * Mark as inconsistent, let the client present it to the user to take
>  action.
>
> * Auto-repair and thus maintain consistency
>
> Looking forward to all feedback.

When you send out a <presence type="probe" /> include the local "view"  
of the subscription state.

The receiving server can then look to see if the state is consisten  
with his own state. If you opt by the lowest trust level (a from/to  
beats a both, none beats all), you should be able to re-sync  
subscription state automagically.

Best regards,



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