Re: [core] Pub/Sub update to use the core multipart content format

Jim Schaad <ietf@augustcellars.com> Sun, 03 March 2019 03:41 UTC

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From: Jim Schaad <ietf@augustcellars.com>
To: 'Michael Koster' <michaeljohnkoster@gmail.com>, =?iso-8859-1?Q?'Ari_Ker=E4nen'?= <ari.keranen@ericsson.com>, =?iso-8859-1?Q?'Jaime_Jim=E9nez'?= <jaimejim@gmail.com>
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Date: Sat, 2 Mar 2019 19:41:37 -0800
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Subject: Re: [core] Pub/Sub update to use the core multipart content format
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Michael,

When I was suggesting using multipart I was thinking more in term of
publishing rather than retrieval.  It would allow for multiple formats to be
sent to the pub/sub server which the server would not need to think about
doing format conversion on but could still return only a single format.

I don't think that one wants to do a multipart retrieval as a general rule
unless the content really a multipart thing.  I guess that the server would
need to be told which way to treat things, but that seems to be a reasonable
query parameter for topic creation.

Jim


> -----Original Message-----
> From: core <core-bounces@ietf.org> On Behalf Of Michael Koster
> Sent: Saturday, March 2, 2019 3:24 PM
> To: Ari Keränen <ari.keranen@ericsson.com>om>; Jaime Jiménez
> <jaimejim@gmail.com>
> Cc: core@ietf.org WG <core@ietf.org>
> Subject: Re: [core] Pub/Sub update to use the core multipart content
format
> 
> OK, I read the multipart draft (expired?) For the no data case we will
just
> send an empty multipart payload (cbor x80).
> 
> It seems like every implementation of pub/sub will be required to support
> only link-format and multipart. The subtype support will be on a topic
basis
> and maybe a broker should have some way to list a set of supported
> subtopics that it can handle. To remind people, a coap pub/sub broker
> doesn't have any notion of "resource state" other than a stored
> representation.
> 
> Best regards,
> 
> Michael
> 
> > On Mar 2, 2019, at 5:27 AM, Michael Koster
> <michaeljohnkoster@gmail.com> wrote:
> >
> > Hi,
> >
> > I am editing the pub/sub draft today and thinking about the multipart
> content format as a way to provide a subscribe or retrieve response for
the
> no data case.
> >
> > It seems to require that the pub/sub client always support the multipart
> format, with no content being one of the format options signaled by
> something like "maybe".
> >
> > Does this seem right to you also? Do we need to invent a new empty
> format code instead of a response code?
> >
> > Best regards,
> >
> > Michael
> >
> >
> >
> >
> 
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