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RE: data streams

From: Nilsson, Claes1 <Claes1.Nilsson@sonymobile.com>
Date: Tue, 9 Jun 2015 14:54:29 +0200
To: 'Ari Keränen' <ari.keranen@ericsson.com>
CC: "Hund, Johannes" <johannes.hund@siemens.com>, Dave Raggett <dsr@w3.org>, Magnus Olsson <magnus.olsson@ericsson.com>, Edoardo Pignotti <Edoardo.Pignotti@nominet.org.uk>, "public-wot-ig@w3.org" <public-wot-ig@w3.org>, "Isberg, Anders" <Anders.Isberg@sonymobile.com>
Message-ID: <6DFA1B20D858A14488A66D6EEDF26AA30370142CD098@seldmbx03.corpusers.net>
Thanks for your informative answer Ari. I am interested in following the further work on the Publish-Subscribe Broker for CoAP.

BR
  Claes



Claes Nilsson
Master Engineer - Web Research
Advanced Application Lab, Technology

Sony Mobile Communications
Tel: +46 70 55 66 878
claes1.nilsson@sonymobile.com

sonymobile.com



> -----Original Message-----
> From: Ari Keränen [mailto:ari.keranen@ericsson.com]
> Sent: den 9 juni 2015 01:34
> To: Nilsson, Claes1
> Cc: Hund, Johannes; Dave Raggett; Magnus Olsson; Edoardo Pignotti;
> public-wot-ig@w3.org; Isberg, Anders
> Subject: Re: data streams
>
> Hi Claes,
>
> On 07/06/15 02:59, Nilsson, Claes1 wrote:
> > Thanks for these links Ari.
> >
> > The Publish-Subscribe Broker for CoAP was new to me. Sounds
> interesting and I am reading the Abstract: "This document defines a
> publish-subscribe broker for CoAP that extends the capabilities of CoAP
> for supporting nodes with long breaks in connectivity and/or up-time."
> >
> > I have a two questions on this draft:
> >
> > * Compared to using MQTT, which are the benefits of the Publish-
> Subscribe Broker for CoAP? Even more lightweight than MQTT as it runs
> over UDP?
>
> CoAP is lighter than MQTT, although it's roughly in the same ball park
> with MQTT-SN.
>
> I think the biggest benefit for CoAP pub-sub broker comes from the fact
> that it integrates well with the rest of the CoAP infrastructure, and
> hence works well with the rest of the web (CoAP was built that way).
>
> Also, you can use the CoAP pub-sub broker to facilitate interworking
> between CoAP and MQTT. This part is not specified yet, but it has been
> the idea all along.
>
> > * In the Introduction section issues with middle-boxes, such as NATs
> and firewalls, and prevention of connecting to a device from the
> Internet are mentioned. If a client is subscribing to a topic the
> specification states that it should use a CoAP GET Observe request to
> the broker. However, when time passes will there not be problems with
> the Observe messages sent from the broker to the client as we can't
> expect NATs and firewalls to keep the communication chain open for a
> long time?
>
> That's true. The initial connectivity problem is solved by client-
> initiated actions, but the keep-alive part needs still needs more work.
> We'll take that to our list of todo-items for the next revision.
>
>
> Thanks,
> Ari
>
> > BR
> >    Claes
> >
> > Claes Nilsson
> > Master Engineer - Web Research
> > Advanced Application Lab, Technology
> >
> > Sony Mobile Communications
> > Tel: +46 70 55 66 878
> > claes1.nilsson@sonymobile.com
> >
> > sonymobile.com
> >
> >
> >
> >> -----Original Message-----
> >> From: Ari Keränen [mailto:ari.keranen@ericsson.com]
> >> Sent: den 4 juni 2015 01:43
> >> To: Hund, Johannes; Dave Raggett; Magnus Olsson; Edoardo Pignotti;
> >> public-wot-ig@w3.org
> >> Subject: Re: AW: data streams
> >>
> >> Hi all,
> >>
> >> I agree that pub-sub model for handling this kind of streams of data
> >> makes a lot of sense.
> >>
> >> For folks not familiar with the IETF work, here's pointers to
> >> relevant drafts.
> >>
> >> Observing Resources in CoAP:
> >> https://tools.ietf.org/html/draft-ietf-core-observe-16

> >>
> >> Publish-Subscribe Broker for CoAP:
> >> https://tools.ietf.org/html/draft-koster-core-coap-pubsub-01

> >>
> >> The observe draft is in final stages to become an RFC while the
> >> pub-sub broker draft is still in early stages of specification.
> >>
> >> I'm one of the co-authors of the pub-sub broker draft and we are
> >> currently updating it for the next IETF meeting. Comments on that
> are
> >> very welcome.
> >>
> >>
> >> Cheers,
> >> Ari
> >>
> >>
> >> On 03/06/15 06:12, Hund, Johannes wrote:
> >>> Hi Magnus,
> >>>
> >>> in the discussions @IETF there are basically two models being
> >>> discussed, even there the discussion is quite related  with the
> used
> >>> protocol (CoAP), the concepts are remarkable generic.
> >>>
> >>> There one Architecture model is having a central pub-sub broker
> (can
> >>> also be “central”  for a small piece of the application such as a
> >> room
> >>> or a home), while the other is more generalized to have a way to
> >>> orchestrate data bindings, i.e. to tell one resource to convey data
> >>> changes to or from another resource. That means I could tell one
> >>> resource to observe another resource (and optionally tell it to
> >> change
> >>> its state accordingly) or I can tell one resource to push any data
> >>> changes to another resource. The pub-sub broker would be a special
> >>> case of that.
> >>>
> >>>   From the current discussions of the WoT framework e.g. between
> >>> Vlad and me, I would see this also covered by the current approach,
> >>> as one “thing” can have properties and you should be able to
> >>> subscribe to a property to get informed on data change.  How this
> >>> subscription is done is dependent on the protocol that the
> framework
> >>> resp. model is
> >> mapped to.
> >>>
> >>> Same goes with events, the main difference between a property
> change
> >>> and an event is that the event might have a greater semantic
> meaning
> >>> e.g. a flatline of the ECG or e.g. might be referring to several
> >>> properties, such as heart rate above a threshold value.
> >>>
> >>> I really think that the model we currently are discussing is
> capable
> >>> of providing these use cases Dave mentioned, but we should define
> >>> higher-level patterns (e.g. sensor value  + threshold as properties
> >>> and an event source for threshold traversal or denying
> subscriptions
> >>> if there is already one active subscription) based on the framework
> >>> that could e.g. have own APIs or be described as such in the TDL.
> >> That
> >>> is for example how the CoRE interfaces are done in the IETF, they
> >>> are basically interaction patterns of a RESTful API.
> >>>
> >>> I was not quite sure in the discussion below: is there the
> >>> suggestion to forsee a way to manage out-of-band streams or is it
> >>> referring to
> >> inband?
> >>>
> >>> Also it might be useful, I am not sure if we should address
> >> management
> >>> of out-of-band streams, as it opens quite a can of worms. If the
> >>> consensus is we do need it, then I would see it sufficient to also
> >>> provide a sort of pattern as mentioned above.
> >>>
> >>> Any thoughts?
> >>>
> >>> Best Regards,
> >>>
> >>> Johannes
> >>>
> >>> *Von:*Magnus Olsson [mailto:magnus.olsson@ericsson.com]
> >>> *Gesendet:* Mittwoch, 3. Juni 2015 10:27
> >>> *An:* Edoardo Pignotti; public-wot-ig@w3.org
> >>> *Betreff:* Re: data streams
> >>>
> >>> Edoardo,
> >>>
> >>> Great if it works I have no practical experience myself using the
> >>> pub-sub for IoT data but understand that there is standards work
> (in
> >>> IETF) that could be possible to reference. What is the Oxford flood
> >>> network, sounds like an Iot mesh?
> >>>
> >>> Br magnus
> >>>
> >>> http://www.ericsson.com/current_campaign

> >>> <http://www.ericsson.com/current_campaign>
> >>>
> >>> *MAGNUS OLSSON *
> >>>
> >>>
> >>> Ericsson AB
> >>> Group Function Technology
> >>> Mobilvägen 1
> >>> 22362 Lund, Sweden
> >>> SMS/MMS +46 706 756814
> >>> magnus.olsson@ericsson.com <mailto:magnus.olsson@ericsson.com>
> >>> www.ericsson.com <http://www.ericsson.com>
> >>>
> >>>
> >>>
> >>> Ericsson
> >>>
> >>>
> >>>
> >>> This Communication is Confidential. We only send and receive email
> >>> on the basis of the terms set out at
> >>> www.ericsson.com/email_disclaimer
> >>> <http://www.ericsson.com/email_disclaimer>
> >>>
> >>> On 2015-06-03 10:19, Edoardo Pignotti wrote:
> >>>
> >>>      Hello,
> >>>
> >>>      I also agree that streams would be a very useful thing to
> >>> support
> >> in
> >>>      the WoT framework.
> >>>
> >>>      I am in favour of a pub-sub broker model. In the oxford flood
> >>>      network we thought very hard how to manage data streams and we
> >> went
> >>>      for a pub-sub model.
> >>>
> >>>      I would be more than happy to discuss this further in the
> >>> context
> >> of
> >>>      our case-study.
> >>>
> >>>      All the best,
> >>>
> >>>      Edoardo
> >>>
> >>>      *From: *Magnus Olsson <magnus.olsson@ericsson.com
> >>>      <mailto:magnus.olsson@ericsson.com>>
> >>>      *Organization: *Ericsson AB
> >>>      *Date: *Wednesday, 3 June 2015 09:04
> >>>      *To: *"public-wot-ig@w3.org <mailto:public-wot-ig@w3.org>"
> >>>      <public-wot-ig@w3.org <mailto:public-wot-ig@w3.org>>
> >>>      *Subject: *Re: data streams
> >>>      *Resent-From: *<public-wot-ig@w3.org <mailto:public-wot-
> >> ig@w3.org>>
> >>>      *Resent-Date: *Wednesday, 3 June 2015 09:05
> >>>
> >>>      Dave,    (and woters)
> >>>
> >>>      Streams sounds like a very useful thing to support :-)
> >>>
> >>>      - For the multiple sinks, why not use a pub sub broker as the
> >>>      identified source of the stream that way any number of sinks
> can
> >>>      attach to that pub-source. Seems to me that setting a proxy
> >> output
> >>>      value to point to a single output is a limitation that might
> >> result
> >>>      in someone creating an upstream proxy to split to multiple
> sinks.
> >>>
> >>>      Any thing should be able to redirect any aspect of their
> source
> >>>      (defined by its meta description) to a nearby pub-sub proxy
> >> service.
> >>>      Still that could be an "on device" (localhost) broker, a home
> >>>      broker, a service provider broker or a public broker etc.
> >>>
> >>>      It seems reasonable to me to have use case such as one part of
> >> the
> >>>      stream for the snapshot, another for the live view a third for
> >> data
> >>>      analysis, a fourth for a remote tele medicine, a fifth for a
> >>>      emergency monitoring function etc.
> >>>
> >>>      - Even discrete value type of sensors could be handled as a
> >> stream
> >>>      if only given long enough time to observe
> >>>
> >>>      - (Not convinced myself) but perhaps any data points should be
> >>>      allowed to be retrieved as a stream with sometime only a
> single
> >>>      value being sent before the connection is being terminated.
> >>>
> >>>      - If there is a possibility to "cascade" (or chaining) the
> >> streamed
> >>>      data points then it might open up for a "network of" data
> stream
> >>>      functions that could apply smartness to the stream such as
> adding
> >>>      timestamps (simple sensors do not have timestamps, but
> sometimes
> >>>      have sample rates), compression, average, de-noising,
> composite
> >> streams.
> >>>
> >>>      Thanks!
> >>>
> >>>
> >>>      Br magnus
> >>>
> >>>      http://www.ericsson.com/current_campaign

> >>>      <http://www.ericsson.com/current_campaign>
> >>>
> >>>      *MAGNUS OLSSON *
> >>>
> >>>
> >>>      Ericsson AB
> >>>      Group Function Technology
> >>>      Mobilvägen 1
> >>>      22362 Lund, Sweden
> >>>      SMS/MMS +46 706 756814
> >>>      magnus.olsson@ericsson.com <mailto:magnus.olsson@ericsson.com>
> >>>      www.ericsson.com <http://www.ericsson.com>
> >>>
> >>>
> >>>
> >>>      Ericsson
> >>>
> >>>
> >>>
> >>>      This Communication is Confidential. We only send and receive
> >> email
> >>>      on the basis of the terms set out at
> >>>      www.ericsson.com/email_disclaimer
> >>>      <http://www.ericsson.com/email_disclaimer>
> >>>
> >>>      On 2015-06-03 09:16, Dave Raggett wrote:
> >>>
> >>>          I am interested in enabling the Web of Things Framework to
> >>>          handle data streams.
> >>>
> >>>          Some sensors produces streams of data as a function of
> time.
> >>>          Data streams can carry one or more data channels where
> each
> >>>          channel is a single number or a vector.
> >>>
> >>>          An example would be an electrocardiography (ECG) sensor
> >>> which
> >> is
> >>>          used to produce a waveform of the heart's activity over a
> >> time
> >>>          period of up to a few seconds (see attached image). In a
> >>>          hospital the sensor and display are connected together
> with
> >>>          electrical leads.
> >>>
> >>>          In the Web of Things, the sensor and the display are both
> >>>          modelled as "things". In place of leads, we set the
> sensor's
> >>>          output property to the display. The display could be an
> >> object
> >>>          in a web page script that displays the waveform using the
> >> HTML
> >>>          CANVAS element, or it could be a remote service, e.g. a
> >> device
> >>>          that acts as an oscilloscope. The display could have
> >> properties
> >>>          that control its behaviour, e.g. how many seconds of data
> to
> >>>          show. It could also have actions, e.g. to freeze the
> >>> display
> >> to
> >>>          allow a waveform to be studied in more detail.
> >>>
> >>>          Script developers ony need to know the object model for
> the
> >>>          sensor and display. The details of the underlying
> protocols
> >> are
> >>>          dealt with automatically by the server platform. For this
> to
> >>>          work, we need a standard way to describe data streams as
> >>> part
> >> of
> >>>          the data model for "things".
> >>>
> >>>          For a simple thing property, e.g. the state of a light
> switch,
> >>>          setting the value of the property on the proxy results in
> the
> >>>          server sending a message to update the physical state of
> the
> >>>          switch. For streams, the semantics is slightly different.
> >>>          Setting the value of the proxy's' output directs the data
> >> stream
> >>>          to the designated object.
> >>>
> >>>          This model assumes that a stream can only be sent to a
> single
> >>>          data sink.  If you want to have multiple sinks, you will
> >>> need
> >> to
> >>>          use a "thing" that acts as splitter. In principle, the
> thing
> >>>          acting as the sensor could do this, e.g. providing one
> output
> >>>          for a data logger, and another for a display.
> >>>
> >>>          p.s. I am planning on implementing this as part of the
> NodeJS
> >>>          server project on GitHub. By the way, there are several
> >> examples
> >>>          of how to create an ECG monitor with Arduino’s if you want
> to
> >>>          build your own.
> >>>
> >>>          —
> >>>
> >>>              Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>>
> >>>
> >>
> >

Received on Tuesday, 9 June 2015 12:55:09 UTC

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