Web of Things Interest Group Teleconference

10 Jun 2015

See also: IRC log


Johannes_Hund, Tobie_Langel, DanhLePhuoc, Dave_Raggett, Kazuaki, Kathy, Kaz, Francois, Tobie, Taki


<trackbot> Date: 10 June 2015

<jhund> Meeting: WoT IG Task Force for APIs and Protocols regular call

<jhund> webex: https://mit.webex.com/mit/e.php?MTID=m78d9162cfa5e71c32233b834b20446d4

Architecture model

<jhund> https://github.com/w3c/wot/wiki

<scribe> Scribe: Tobie_Langel

<jhund> https://github.com/w3c/wot/wiki/Architecture-Model

Architecure Model

jhund: architecture model is on GitHub, see links above
... as W3C wiki doesn't take pics.
... GH account required.
... Images are built using PlantUML.
... servient model represents a real thing.

<jhund> https://github.com/w3c/wot/wiki/Architecture-Model#assumptions-on-virtual-instance

k_nimura: 1st clarify what the servient instance is
... virtual instance has actions, resources and events
... virtual instance ties to a real thing
... multiple virtual instances can be allocated to a WoT Servient

<jhund> Assumptions on Virtual Instance: Virtual Instance has actions, resources, and event sources. Actions, resources, and event sources contain APIs of a thing and code that how to actuate or sense a thing including protocol binding. A Virtual Instance ties to a real thing. More than one Virtual Instances can be allocated to a WoT Servient. Virtual Instance is instantiated by WoT Servient from script or code (i.e. Device Driver).

k_nimura: Virtual Instance is instantiated by WoT Servient from script or code

jhund: good wrap up of the assumptions we have. Any thoughts?
... matches dsr's implementation

DanhLePhuoc: the virtual thing is defined on top of other things
... : virtual instance can be a combination of multiple physical things combined with virtual things.

jhund: yes composition exists, e.g. home automation
... we have several examples of that
... one thing representing as a collection of multiple thing.
... difference with a Web service is a web service is not structured.
... here we have some knowledge about how the service works.
... draw similarity between Web service and virtual instance ("thing") in wiki terminology/definition section.

xxx: will do, thank you

jhund: that was a recap of arch model so far

DanhLePhuoc: one question still: re streaming part

jhund: so we have resources (props) + event sources
... whenever a prop change --> event emmitted
... plus higher level events
... e.g. an alarm
... these are where we see data streams
... subscriptions point to resource or data source
... you get a notification when data changes

DanhLePhuoc: you want to subscribe to parts of the stream only
... CG on stream processing
... you want the server to be aware of what the subscriber is interested in => more efficient

jhund: two parts to tying the subscription to the servient:
... choose which protocol
... add threshold (this is where you could have complex event processing)
... we should keep this in mind when we design the servient

DanhLePhuoc: this is tied to the event source

jhund: if you have a suggestion on how this would look like, please added to the wiki

dsr: wrt to streams, there are diff reqs
... data logging: high freq of points, you want continuity of the data
... different approach to streams in different languages
... we must seems about what the abstraction of a stream is?
... we need to look more carefully at the use cases and reqs.

jhund: what does this mean for the model we established so far?
... do we need static props and streams props?

<DanhLePhuoc> +1 for further study on incorporate streams/stream properties

dsr: the typing system we have for props: one of these types will be a timestamped stream
... this is about refining the type system

jhund: ties to the conversation about the type of properties

dsr: no need to restrict it to flat values
... we need a list of examples (types) + uses cases.

jhund: agreed.

dsr: I can try to so such a list.

<jhund> https://github.com/w3c/wot/wiki/Architecture-Model

jhund: well, put it as part of the arch model
... see above link.

Presentation of Dave's Implementation

dsr: [presenting]

<dsr> https://github.com/w3c/web-of-things-framework

dsr: to understand, build!
... worked on this with a friend (Joachim_Baumberger)
... starting a node.js-based implementation
... for micro-controllers: arduino and ESP8266
... big maker community around the micro-controller route
... starting off by looking at node sockets in the nodejs implementation
... http for meta data, then websockets for messaging
... here's an example with door + light switch
... here's how you do proxies
... interesting issues with dependencies
... IRL a lot of devices are sleeping and won't be updated until they're next waking up cycle

jhund: question: first you use http for meta-data, then web-socket for the messaging
... where's the seperation between both?
... so we can implement multiple protocols for the messaging

dsr: See GitHub issue #13

<dsr> https://github.com/w3c/web-of-things-framework/issues/13

<dsr> s/YYY/Joachim Bauenberger/

<tidoust> [I already noted during the F2F but still note that the use of "@" as a prefix for events, properties and actions definitions in the JSON is extremely weird and would actually conflict with JSON-LD, that chose this prefix character specifically because normal people would not use that character to defined properties]

dsr: general discussion with devs should be raised on the community list
... three github projects: node.js, microcontrollers, Go.
... also test framework
... what kind of test framework makes sense?
... plan for the IG is to draft a charter for the WG for review at the F2F in july to launch the WG by EOY
... for WG to be successful, we need implementation experience, idea on how to do testing, etc.

jhund: moving agenda points to next meeting.
... adjourning
... thanks everyone

next meeting next week at 5:00pm CEST

Summary of Action Items

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$Date: 2015/06/10 08:07:45 $

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Found Scribe: Tobie_Langel
Present: Johannes_Hund Tobie_Langel DanhLePhuoc Dave_Raggett Kazuaki Kathy Kaz Francois Tobie Taki
Found Date: 10 Jun 2015
Guessing minutes URL: http://www.w3.org/2015/06/10-wot-ap-minutes.html
People with action items: 

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