Re: [Simple] SUBSCRIBE for xcap-diff event sent by the presence server to the XCAP server

[Jari Urpalainen <[e-mail]>]

On Mon, 2009-12-28 at 00:36 +0100, ext Iñaki Baz Castillo wrote:
> Hi, the way a presence server receives notifications for changes in XCAP 
> documents (so it can notify the watchers) is by subscribing to the XCAP server 
> for the event "xcap-diff" as specified in:
>   http://tools.ietf.org/html/draft-ietf-sip-xcapevent
> 
> I would like to understand how such SUBSCRIBE sent by the presence server 
> looks. The above draft just shows examples when a SIP user send such SUBSCRIBE 
> but no one example when the subscriber is the presence server.
a presence server can be a "normal" xcap-diff client. Acls though would
be quite different than with the typical use-case.   

> 
> For example, let's imagine a simplified case in which there are just two XCAP 
> applications ("pres-rules" and "resource-lists").
> 
> The presence server should subscribe to users documents. AFAIK the presence 
> server would send a SUBSCRIBE as follows:
> 
> 
>    SUBSCRIBE sip:[e-mail] SIP/2.0
>    From: sip:[e-mail]
>    Accept: application/xcap-diff+xml
>    Event: xcap-diff; diff-processing=no-patching
>    Content-Type: application/resource-lists+xml
> 
>    <?xml version="1.0" encoding="UTF-8"?>
>    <resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists">
>      <list>
>        <entry uri="pres-users/users/" />
>        <entry uri="resource-lists/users/" />
>      </list>
>    </resource-lists>
> 
> 
> Then when any user creates or modifies a XCAP document for those auids, then 
> XCAP server would sent a NOTIFY to the presence-server telling the document 
> addition/modification.
> 
> 
> Doubts:
> 
> - Is the above correct? (is it defined somewhere?)
theoretically yes, if you really have a distributed system, and you
indeed must use a public interface (though acls are beyond the scope of
xcap-diffevent). But in practice however, i'd assume you'd use some
"internal" api for this, and you wouldn't need to have a duplicated xcap
database (or equivalent).

> 
> - Most probably the presence-server is just interested in "index" documents 
> for both XCAP applications. However it would receive notifications for every 
> document created by any user even if it's not called "index". Is it the 
> expected behavior? How to ask in the SUBSCRIBE that there is noly interest on 
> "index" called documents?
there's no such thing like reg-expressions (or some search) in
diff-event subscriptions, though i don't think it's a big problem in
reality as you can easily skip those docs that you aren't interested in.

> 
> - Could the notification from the XCAP server to the presence server work with 
> PUBLISH rather than SUBSCRIBE & NOTIFY? This is: when a XCAP document is 
> modified the XCAP server sends a PUBLISH to the presence server with xcap-diff 
> body. Does it make sense?
Sure, but i cannot see any actual benefit

> 
> - And last question. Are all my questions defined in IETF docs? or do they 
> require specifications on top of IETF docs as OMA specs?
> 
at least rfc's will give you some hints how to make a system what you
are probably aiming at, i don't know about other specs though.

br, jari