W3C home > Mailing lists > Public > public-automotive@w3.org > June 2016

Re: Draft Specification for Service Based Approach Using WebSockets

From: Streif, Rudolf <rstreif@jaguarlandrover.com>
Date: Tue, 7 Jun 2016 15:58:24 -0700
Message-ID: <CANpGCG+U5QBBVwO=4jsVko10d9HG09K2B-dbXHW1_4LzsSkHzA@mail.gmail.com>
To: Paul Boyes <Paul.Boyes@inrix.com>
Cc: Peter Winzell <Peter.Winzell@melcogot.com>, "Crofts, Adam" <acrofts1@jaguarlandrover.com>, public-automotive <public-automotive@w3.org>, Kevin Gavigan <kgavigan@jaguarlandrover.com>, Peter Virk <pvirk1@jaguarlandrover.com>, Lovene Bhatia <lbhatia@jaguarlandrover.com>
Adam, Kevin,

Thank you for adding this to the wiki (which reminds me that I still have
to add the VSS details to it).

A couple of questions:

Client-side Subscription ID
--------------------------------------
The server returns an acknowledgement when a subscription attempt was
successful. The acknowledgement contains a server-side subscription ID and
the subscription parameters so that the client can identify the request. I
suggest for the subscription request to contain a client-side subscription
ID/handle. That would alleviate the client from parsing the subscription
parameters and matching them to the request. That client-side subscription
ID could also be included with the data sent to the client.

Repeated Interval Subscription
--------------------------------------------
The subscribe action in the table does not define what happens when the
client sends repeat subscription messages with different intervals for the
same signal path. Would that result in another subscription or in a change
of the interval of the previously made subscription? I would think that it
should change the subscription interval. However, if we used a client-side
subscription ID and the client uses a different ID for the subsequent
subscription request to the same signal with a different, or essentially
any interval, would that result in a change of the previous subscription
despite the different client ID (eventually with an updated client-side
subscription ID)?

Repeated Onchange Subscription
-------------------------------------------------
Are repeated onchange subscriptions supported for the same signal but with
different above and below thresholds? One could think of multiple
subscriptions to define bands of engine.rpm: (above: 0, below: 1000),
(above: 1000, below: 2000), ... If that is possible then overlapping
intervals/bands would result in multiple messages?


BTW, I would love to drive the car from the example with 1200 kW. :) (That
should actually be engine.power as engine.tps is throttle position with a
value between 0 and 100).


Thanks,
Rudi




On Tue, Jun 7, 2016 at 6:18 AM, Paul Boyes <Paul.Boyes@inrix.com> wrote:

> Excellent indeed.  I will look at this in detail later today.
>
> *Paul J. Boyes* | INRIX | Director of Telematics and Standards - OpenCar
>  |  206-276-9675 | paul.boyes@inrix.com <bryan@inrix.com> | www.inrix.com
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.inrix.com_&d=BQMFAg&c=QbuapHRvbn0JdC8vTVkPHg&r=PRAN7lum5Ra662QLho8LU3bhFjBvLXn3bBkFbW0Amjo&m=V5l0WXfOEJwhcE0JsN06mQ5SQhpXL-DuAuK3YcnTZoc&s=OqQVi_DcS5rv8or8hZdFvY0re6YF0Wl-_8okxrxOF0w&e=>
>
> On Jun 7, 2016, at 3:56 AM, Peter Winzell <Peter.Winzell@melcogot.com>
> wrote:
>
> Excellent !
> I have just browsed through – Thank you for your hard work!!
> /pw
>
> *From:* Crofts, Adam [mailto:acrofts1@jaguarlandrover.com
> <acrofts1@jaguarlandrover.com>]
> *Sent:* Monday, June 6, 2016 12:58 PM
> *To:* public-automotive
> *Cc:* Kevin Gavigan; Peter Virk; Lovene Bhatia
> *Subject:* Draft Specification for Service Based Approach Using WebSockets
>
> Hi All,
>
> Kevin and I have drafted a specification for the service based approach
> using WebSockets, as discussed in Issue 81
> <https://github.com/w3c/automotive/issues/81>. The draft can be found in
> the working group wiki here
> <https://www.w3.org/auto/wg/wiki/Vehicle_Information_Service_Specification#WebSocket_2>
> .
>
> The specification builds upon the approach raised by Powell Kinney, using
> a single WebSocket to send JSON data structures to the server. The JSON
> structure specifies the desired vehicle signal specification (VSS) path, an
> action parameter to specify get, set, subscribe or unsubscribe as well as a
> number of optional parameters.
>
> This specification allows:
>
>    - Use of the VSS, including wildcards and indexing
>    - GET/SET over WebSocket
>    - SUBSCRIBE to receive change notifications, allowing settable change
>    thresholds and upper/lower bounds
>    - SUBSCRIBE to receive notifications at a given time interval.
>    - UNSUBSCRIBE via a subscription handle
>    - UNSUBSCRIBE from all notifications
>    - Security tokens to be passed from the client to the server, such as
>    OAuth 2.0
>
> We'll go through this on the call on Tuesday night and look forward to
> hearing your thoughts.
>
> Kind regards,
>
> Adam
>
> --
> *Adam C**rofts MEng (Hons) MIET*
> Connected Infotainment
> Vehicle Engineering
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>
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>


-- 
*Rudolf J Streif*
System Architect - Open Source Initiative
Open Source Technology Centre

*M:* +1.619.631.5383
*Email:*  rstreif@jaguarlandrover.com



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Received on Tuesday, 7 June 2016 22:58:53 UTC

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