WoT Discovery – 13 December 2021

Meeting minutes

Minutes

Dec-6

McCool: OK with the minutes
… any corrections? objection?

(none; approved)

Logistics

McCool: turns out that there will be a conflict on Jan 10...
… so can't attend myself

Farshid: can chair the meeting for you

McCool: ok
… (Farshid will chair the Discovery call on Jan 10)

PRs

PR 243

PR 243 - Add slight wording changes

McCool: Christian's PR
… (goes through the PR)

Farshid: two other comments there
… you can commit it

McCool: let's figure it out
… people agree with the proposed change here?

Farshid's proposed change

diff - section 6.2.2.1.5 Listing

McCool: I'm fine with the proposed change

Kaz: just to make sure, you mean we'd like to remove the second assertion cused by "particularly, it MUST include the same limit argument". Right?

McCool: yes
… (applies the change)
… and what about the change on "pagination"?

Farshid: around there

McCool: ok

(merged)

PR 248

PR 248 - Change XPath response to allow all responses

McCool: (goes through the PR)
… still have a question what the data schema should be
… would like to read through the spec
… anyway, need to do is having a sentence
… could do that later, but can add one now

Farshid: looked at the TD spec
… need some change there as well

McCool: right
… the description within TD is also wrong at the moment

Issue 86 - "Thing description" for Directory should be a "Thing Model"

McCool: note the data schema for query responses needs some consideration
… e.g., the return data schema for XPath 3.1 may not include objects
… since it is converted from XML
… see https://github.com/w3c/wot-discovery/pull/248

McCool's comments for Issue 86

McCool: (visits section "8.1 Directory API Thing Model" from WoT Discovery ED)

8.1 Directory API Thing Model

McCool: would like to get this done sooner than later
… Farshid, can you work on that?

Farshid: yes, I can

Issues

Issue 247

Issue 247 - XPath response data model

McCool: would like to close this Issue

Farshid: can be closed by merging PR

PR 248 - Change XPath response to allow all responses

McCool: (sees the section 6.2.2.4.2 from the diff)

diff - 6.2.2.4.2 Syntactic search: XPath

McCool: any objection to merge this PR?

(none)

merged

Issue 249

<McCool> Issue 249 - Multiple Responses from Peer-to-Peer Discovery

McCool: one possibility is listing APIs

Farshid: data type is not TD any more
… array is not a Thing

Cristiano: wondering if we could refer to the core link format

McCool: (adds comments)
… could also return one TD that links to other TDs
… if we return an array in DNS service type, is it a Thing or a Directory?
… maybe we should use CoRE-RD format for .well-known?
… we have to change the definition

Farshid: what would be the content type?

McCool: we already have an IANA content type for TDs
… but not for "collections of TDs"
… so what would the content type of the .well-known end point be?

Farshid: what would happen for a gateway?
… thinking out of box

McCool: could also return one TD that links to other TDs This gives a TD similar functionality of CoRE-RD but without bringing in another spec

<FarshidT> ThingLink: https://w3c.github.io/wot-discovery/#exploration-mech

Farshid: Exploration Mechanisms

McCool: ThingLink type

Cristiano: in node-wot, servient exposes itself using a TD

McCool: we have 2 choices
… but can a Thing expose the second TD?
… multiple Things in the same script?

Cristiano: yes, that's possible

McCool: this would lead to different cases for one and multiple TDs
… do we switch between them?
… my preference is always using Thing Links
… the disadvantage is that we need to fetch two TDs

Farshid: if you refer to the spec, there are three use cases
… and maybe we might need the fourth one

example 2

McCool: if we return the TD itself for "singleton" Things then we avoid this problem for the simple case (=one Thing for a given IP)

(some more discussion on possible solutions)

McCool: pushing down node for tree

Cristiano: can try to implement that

McCool's comments on several possible options

leaning towards [[Using a ThinkLink TD, but only when there are multiple Things at a given IP address.]]

McCool: We could ALLOW people to use a ThingLink even if they have only one TD.