W3C home > Mailing lists > Public > public-automotive@w3.org > September 2020

Re: Comparison of compression algorithms

From: Ulf Bjorkengren <ulfbjorkengren@geotab.com>
Date: Tue, 1 Sep 2020 21:35:05 +0200
Message-ID: <CAHfMbK_8Rgir=MxEUTmoLoU2B=tp2gXphQ96jUbufWuAavWpqA@mail.gmail.com>
To: Ted Guild <ted@w3.org>
Cc: Gunnar Andersson <gandersson@genivi.org>, public-automotive <public-automotive@w3.org>
>> For a variety of reasons (security, connectivity, car being off), data
being off-boarded from vehicle to the cloud will be pushed, not pulled.
I don't see this being an absolute truth. I think the concerns mentioned
can be mitigated, thus enabling the pull scenario.
I guess it is the OEMs that ultimately makes this call, so I hope to hear
their view on it.
BR
Ulf


On Tue, Sep 1, 2020, 21:10 Ted Guild <ted@w3.org> wrote:

> On Tue, 2020-09-01 at 11:28 -0400, Ted Guild wrote:
> > We can/should also explore alternate formats Gunnar suggested
> >
> > https://en.wikipedia.org/wiki/Apache_Avro
> > https://en.wikipedia.org/wiki/Protocol_Buffers
> >
> > As these messages being transmitted are fairly small to begin with
> > and
> > in-vehicle use case will have extremely low latency, I also want to
> > try
> > to understand how/where this would be more useful as
> > encoding/compressing and decoding will cost time and depending on
> > method non-negligible cpu. If the client app is just sampling to
> > offboard and won't unpack (decode), then we probably should look at
> > Extended Vehicle and other solutions being used for off-boarding in
> > addition to formats. What problem[s] are we trying to solve here?
>
> We confirmed on the call today the primary use case is for off boarding
> data.
>
> For a variety of reasons (security, connectivity, car being off), data
> being off-boarded from vehicle to the cloud will be pushed, not pulled.
>
> Gen2 server instance can reside either in-vehicle or on a server in the
> cloud.
>
> For in-vehicle client apps that will be residing on the vehicle or
> nearby (local network) trusted devices, compression is not needed.
> Cloud servers will not be permitted to connect to Gen2 (ports not open)
> on a vehicle to make pull requests. Gen2 supports clients making pulls,
> HTTP GET and subscribe on Web Socket, it cannot initiate a push to
> server in the cloud.
>
> Gen2 supporting alternate, including binary, formats besides JSON for
> more efficient local storage until it can send buffered data off the
> vehicle would help with 'every byte counts' when sending data off the
> vehicle.
>
> VSS in protobuf format can make a ton of sense, perhaps with some
> further optimization along lines of what Ulf and Sanjeev have been
> working on.
>
> Gen2 server residing in the cloud, exposing data already off-boarded
> can respond to pull requests from client apps running elsewhere in the
> cloud. Compression makes sense there.
>
> If someone has a different architecture in mind where vehicle<->cloud
> connections differ fundamentally or we can translate a pull to push by
> redirecting and caching/buffering data, I would like to hear it.
>
> --
> Ted Guild <ted@w3.org>
> W3C Automotive Lead
> https://www.w3.org/auto
>
>
Received on Tuesday, 1 September 2020 19:35:32 UTC

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