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

Michael Koster <> Sat, 02 March 2019 23:23 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 3D6BA130F2F for <>; Sat, 2 Mar 2019 15:23:59 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id 4lJXSoYbo4LN for <>; Sat, 2 Mar 2019 15:23:57 -0800 (PST)
Received: from ( [IPv6:2607:f8b0:4864:20::530]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 21330128D52 for <>; Sat, 2 Mar 2019 15:23:57 -0800 (PST)
Received: by with SMTP id b2so728438pgl.9 for <>; Sat, 02 Mar 2019 15:23:56 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=daLeJ6O8ozv8puqf8bQSfKfptiDZyHnLeYZZpoRsFKI=; b=otkrj+JToq9N7IDtyNrbethtNAEPk7xENRrEQVi420jbrdcayB/j1yZkBzSWunjOI7 66QB8GXCjR6kD+zQ3bS4AHTcrsCjNzs0yxDYhltaAwg1p8FXYOU7FT7e48t2zj8x+6Ih Rv3pveUkown12jLoIf/GqkysxK6Pv9YspN3eZySyiZihmOTKpfUGhZJxRPrj354/vskI 5FIZqBq00HI6A354L8RbqkqsCD7qQGyTGxcLzUxl5vM1THWrm5urg1yO+5rkIOcaug4L StuW5oXCY+A35XsJtK0QCPTHPtTCIZpfFSY33muRWwEwI6cPe0iLHRZfTT5NKoe4/f+v GE/A==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=daLeJ6O8ozv8puqf8bQSfKfptiDZyHnLeYZZpoRsFKI=; b=NS36YD2vdgVczIEZ59zaOxdMN7ARry57qJ8qBS6GirTU4PWaYpxNOOyh3zf4UWksU/ WXu9Xpcy4+b1ERSblfdbbpSbKjNcl2HNC7ZZcp1r+bAe8V+57LuQTcS3q7u66q0cm249 AQleLd03zUgcBZhKYRI8M9y+KsSLPf1434WUelSUxXTHYOFG3ofaQqfPqnhvCGcscfP6 Gb7h/VVK6f8zySlIN+28djit8fRg5PomWP30EFVXjEBiBMEmhen98RfnB2CCXfH8Ksl6 FjKRBqUd4IpMBeMT8zypkBDWHTdDJI7mtkIil9sbzs0oF08Eolj5OIJQvjOIzXT7fuy+ vXkg==
X-Gm-Message-State: APjAAAV61H6XXjPhBRomQTDTDt99yeAEVIB0aPTDjJSg8JmLAIWY98RQ 3HQc0GwMsMgFms/NbN2Cn9s=
X-Google-Smtp-Source: APXvYqxiR7SZL7k0VKvB63jOltq5gMuqJFSO4XABMTN5OFM+2r4OB3soS2jDmdwCHmAQKnuEBUdn0w==
X-Received: by 2002:a63:6b03:: with SMTP id g3mr11674357pgc.239.1551569036217; Sat, 02 Mar 2019 15:23:56 -0800 (PST)
Received: from [] ( []) by with ESMTPSA id v22sm4974245pfa.49.2019. (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 02 Mar 2019 15:23:55 -0800 (PST)
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\))
From: Michael Koster <>
In-Reply-To: <>
Date: Sat, 2 Mar 2019 15:23:53 -0800
Cc: Carsten Bormann <>, " WG" <>
Content-Transfer-Encoding: quoted-printable
Message-Id: <>
References: <>
To: =?utf-8?Q?Ari_Ker=C3=A4nen?= <>, =?utf-8?Q?Jaime_Jim=C3=A9nez?= <>
X-Mailer: Apple Mail (2.3273)
Archived-At: <>
Subject: Re: [core] Pub/Sub update to use the core multipart content format
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Constrained RESTful Environments \(CoRE\) Working Group list" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Sat, 02 Mar 2019 23:24:04 -0000

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,


> On Mar 2, 2019, at 5:27 AM, Michael Koster <> 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