Re: [core] Questions & Comments for PubSub updated Proposal
Christian Amsüss <christian@amsuess.com> Thu, 01 August 2019 08:46 UTC
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Date: Thu, 01 Aug 2019 10:45:58 +0200
From: Christian Amsüss <christian@amsuess.com>
To: Jim Schaad <ietf@augustcellars.com>
Cc: core@ietf.org
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Subject: Re: [core] Questions & Comments for PubSub updated Proposal
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Hello Jim, hello pubsub authors, my personal take on this: I think that most those points can addressed by a variation on the proposal that has been floating but not made its way into the text yet: Rather than all attributes being attached to the topic, some are on the data resource. Compare the following to item 3.5: Request: GET </ps/topics/1234> Response: 2.05 Content Content-Format: CoRAL rdf:type <http://example.org/pubsub/topic> has-published-item true publish -> </ps/data/1234> [ method 3 ] created dt'2019-07-08T15:35:00+0200' last-modified dt'2019-07-08T15:35:00+0200' owner <http://ericsson.example/people/ari> max-rate 50 expires dt'2019-07-15T15:35:00+0200' topic-data </ps/data/1234> { unit "Cel" rt "oic.r.temperature" # that was "topic-title" on the topic in proposal.txt title "My Office Room Temperature" # that was "publisher" on the topic in proposal.txt owner <http://ericcson.example/people/klaus> building 18 floor 1 } We'd still need to, for all the properties involved, decide which terms to use and where to attach them, but it completely sidesteps the topic of inheritance (which would indeed be tricky -- the resource type of a control resource is "pubsub topic control resource", if it's a oic.r.temperature at the same time, that's ... odd). A good criterion for whether something is an attribute of the control or the data resource is the question "Does it matter whether this is used in a pubsub context?": If it is, it should be on the control resource, otherwise it's on the data resource. This does still not quite answer this: > 2. It is not clear to me if a data node is supposed to be able to provide a > CoRAL document for information that relates to it. If someone only knows the data resource, there's no way back from there to the control resource, and no way to get its metadata (that'd be a PROPFIND-style operation probably, and I don't think we want that). There are still CoRAL statements about the topic, but the easiest way to obtain them is to look into the control resource's CoRAL document that describes the topic as well as above. (Which is also how they could be updated, by PATCHing that resource once a patch format for CoRAL is there, or by PUTting back a modified representation, where the server would reject changes it can't do, like the created date or the topic-data URI). Best regards Christian -- To use raw power is to make yourself infinitely vulnerable to greater powers. -- Bene Gesserit axiom
- [core] Questions & Comments for PubSub updated Pr… Jim Schaad
- Re: [core] Questions & Comments for PubSub update… Christian Amsüss
- Re: [core] Questions & Comments for PubSub update… Jim Schaad