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RE: [discovery-api] how does serviceavailable function in practice

From: <Cathy.Chan@nokia.com>
Date: Thu, 7 Feb 2013 20:14:38 +0000
To: <jean-claude.dufourd@telecom-paristech.fr>, <derhoermi@gmx.net>
CC: <public-device-apis@w3.org>
Message-ID: <A46437648ECB3D4F852B077AFF9099F51C93A959@008-AM1MPN1-061.mgdnok.nokia.com>
> -----Original Message-----
> From: ext Jean-Claude Dufourd [mailto:jean-claude.dufourd@telecom-
> paristech.fr]
> Sent: Thursday, February 07, 2013 8:44 AM
> To: Bjoern Hoehrmann
> Cc: public-device-apis@w3.org
> Subject: Re: [discovery-api] how does serviceavailable function in
practice
> 
> Thanks for the fast answer.
> If the serviceavailable event itself does not provide a way to get the
> NetworkService object, and the NetworkServices object received by the
> successCallback is immutable, where do I get the information ? Rich ?

Not Rich but still want to give it a shot. ;-)

Upon receiving the serviceavailable event, the web app would most likely
want to issue a new getNetworkServices call to retrieve the fresh list of
available network services. A new NetworkServices object will be provided at
the success callback.

See towards the end of Section 5.2 (which actually seems like an odd place
for this text).
[[Services available within the local network can connect and disconnect at
different times during the execution of a web page. A user agent can inform
a web page when the state of networked services matching the requested valid
service type change. Web pages can use this information to enable in-page
experiences for communicating the state of networked services with the
ability to change the particular service or set of services the page is
connected to by re-invoking the getNetworkServices() method.]]

Regards, Cathy.

> Thanks
> JC
> 
> Le 7/2/13 14:39 , Bjoern Hoehrmann a écrit :
> > * Jean-Claude Dufourd wrote:
> >> Let us imagine that after a first call to getNetworkServices, I get a
> >> NetworkServices object with 0 entries.
> >> So I have to listen to the serviceavailable event on that
> >> NetworkServices object to get any new matching service.
> >> Probably, the event handler is going to provide me with a new obect
> >> of type NetworkService. Is that correct ?
> > Based on the current Working Draft that would not be possible because
> > the `serviceavailable` event object implements only the Event
> > interface which lacks support for such information. That would also
> > seem to be odd design. I would rather think the object the listener is
> > registered on is mutated prior to the dispatch of the event.
> >
> >> I did not find in the spec where this is specified.
> >> What did I miss ?
> > In <http://www.w3.org/TR/2012/WD-discovery-api-20121004/> section 7 in
> > the first list in the sublist in the fourth list the third item
> > mentions `serviceavailable`. You can then step back through the code
> > to see what effect the individual assembly instructions, like
> > "increment service manager's servicesAvailable attribute by 1" have
> (reverse-engineering).
> 
> 
> --
> JC Dufourd
> Directeur d'Etudes/Professor
> Groupe Multimedia/Multimedia Group
> Traitement du Signal et Images/Signal and Image Processing Telecom
> ParisTech, 37-39 rue Dareau, 75014 Paris, France
> Tel: +33145817733 - Mob: +33677843843 - Fax: +33145817144
> 



Received on Thursday, 7 February 2013 20:15:13 UTC

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