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Here is a suggestion of what I imagine the "core" Telepathy channel
API would look like (Channel.XPMNServiceProviderConnection). The
"higher-level" profile channel would use the functionality of this
channel to provide a simple API.<br>
<br>
Is it reasonable that the signals use the exact data provided to the
methods (such as 's: Value' and 'xml: Value'), or should I let the
methods return an ID or something and track the reply using that?<br>
<br>
<blockquote>A channel type for managing communication between two
XPMN devices. Due to the nature of XPMN, this channel can only be
used with XMPP connections.<br>
<br>
While it is technically possible for XPMN application developers
to use this channel directly, application developers SHOULD
implement a higher-level and profile-specific channel instead
(which internally creates an instance of this class).<br>
<br>
Rationale: Using this channel directly will force the application
developer to deal with low-level XMPP technicalities.
Additionally, a profile-specific middle-layer would allow an
abstracted and usable API.<br>
<br>
You can use this channel to execute commands, get and set simple
and complex variables as well as subscribe and unsubscribe to
events (variable updates) on the service.<br>
<br>
<b>Methods</b><br>
<br>
ExecuteCommand (xml: Command)<br>
<br>
GetAllVariables (s: EventName)<br>
GetLatestVariable (s: EventName)<br>
<br>
SetSimpleVariable (s: EventName, s: Value)<br>
SetComplexVariable (s: EventName, xml: Value)<br>
<br>
Subscribe (s: EventName)<br>
Unsubscribe (s: EventName)<br>
<br>
<b>Signals</b><br>
<br>
Subscribed (s: EventName)<br>
Unsubscribed (s: EventName)<br>
<br>
CommandExecuted (xml: Command, xml: Result)<br>
<br>
SimpleVariableReceived (s: EventName, s: Value)<br>
ComplexVariableReceived (s: EventName, xml: Value)<br>
<br>
SimpleVariableSet (s: EventName, s: Value)<br>
ComplexVariableSet (s: EventName, xml: Value)<br>
<br>
<b>Telepathy Properties</b><br>
<br>
auto_subscribe_features : <list of string> - read only<br>
</blockquote>
<br>
I appreciate any feedback, of course! :-)<br>
<br>
Thanks!<br>
<br>
Best,<br>
Jon Kristensen<br>
<br>
On 01/03/2011 03:17 PM, Jon Kristensen wrote:
<blockquote cite="mid:4D21DA63.2010705@jonkristensen.com"
type="cite">
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charset=ISO-8859-1">
Hello Telepathy people!<br>
<br>
I'm developing an XPMN media server called Pontarius. I'm
currently looking into how XPMN could be integrated with
Telepathy. You can read about Pontarius at <a
moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://www.pontarius.org/">http://www.pontarius.org/</a>.<br>
<br>
First off, let me clarify some XPMN terms:<br>
<br>
<b>XPMN:</b> Stands for Extended Personal Media Network and is a
decentralized media network software architecture. It allows
extended media networks to communicate seamlessly and addresses
service discovery (allowing devices to find and identify each
other and their capabilities), security (access control,
encryption) and extensibility (making it easy to extend for future
use cases), all while being easy to set up and use. All-in-all,
it's an extremely powerful way to arrange your media networks.<br>
<br>
<b>Extended media network:</b> An overlay network consisting
(XPMN) devices from one or more networks, such as home networks.
One problem that XPMN solves is that devices are able to
communicate (over for example Internet) even though they belong to
different subnetworks.<br>
<br>
<b>Service:</b> A specific task or set of tasks that devices may
be capable of fulfilling. One example could be a TV playback and
recording service.<br>
<br>
<b>Device:</b> A logical entity in the extended media network. It
does not have to be a physical device; one physical device can
contain multiple (XPMN) devices. Devices are often bound to a
specific action (such as controlling media playback). A device may
be a controller, a service provider, or both.<br>
<br>
<b>Controller:</b> A device controlling one or more services.
Controllers can also be service providers. An example of a
controller could be a smartphone application that can act as a
remote control for a media player service, allowing the user to
play/pause, change the volume, etc.<br>
<br>
<b>Service provider:</b> A device providing one or more services.
Service providers can also be controllers.<br>
<br>
<b>Profile:</b> A profile is an extension on top of the XPMN
architecture. It is a specification that describes a service and
includes the communication protocol used between controllers and
service providers. There can be many implementations of any given
profile, and they should be seamlessly inter-operable.<br>
<br>
A XPMN device is basically a connected XMPP account. A directory
service could be using the full Jabber ID <a
moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:sprint3@test.pontarius.org/pontarius-directory">sprint3@test.pontarius.org/pontarius-directory</a>.
XPMN devices communicate by exchanging general IQ get/set/result
messages as well as a small subset of the pubsub spec (like
subscriptions, events and items requests). Service discovery
capabilities also play a part. The mechanics for this is the same
for every profile. See The Status and Variable Event Mechanism at
<a moz-do-not-send="true"
href="http://www.pontarius.org/test/0-1-alpha-2/">http://www.pontarius.org/test/0-1-alpha-2/</a>
for a brief (and incomplete) example of what it could look like.<br>
<br>
Every XPMN profile has a specialized API for the job that it's
doing, and they all use the above mentioned methods to do their
job. One simple profile could talk to a media player service to do
things like start and stop playback (think remote control), while
another profile can negotiate and download some data over a Jingle
and SOCKS5 connection from some kind of transfer service. The
external API for these profiles should be made as simple as
possible, and the profile should hide the "core" XPMN module (from
the previous paragraph) from the third party developer. He should
probably only know about the TpAccount he want to connect with,
and the full JID of the service he wants to talk to. He would most
likely be developing a Telepathy client.<br>
<br>
I don't really know where the "core" XPMN code and the
profile-specific (remote control, data transfer) code should go,
what it should be (Telepathy channels?) and how they should
communicate. What role could Gabble sidecars play here?<br>
<br>
Any ideas, comments or suggestions would be very appreciated!<br>
<br>
You can read more in-depth details about XPMN in Dirk Meyer's
thesis at <a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://elib.suub.uni-bremen.de/diss/docs/00011878.pdf">http://elib.suub.uni-bremen.de/diss/docs/00011878.pdf</a>.
Also feel free to ask questions to this mailing-list or to me
directly. :-)<br>
<br>
Thanks!<br>
<br>
Warm regards,<br>
Jon Kristensen<br>
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