Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03
Jim Schaad <ietf@augustcellars.com> Sat, 09 March 2019 19:39 UTC
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From: Jim Schaad <ietf@augustcellars.com>
To: 'Laurence Lundblade' <lgl@island-resort.com>, 'Francesca Palombini' <francesca.palombini@ericsson.com>
CC: cbor@ietf.org, draft-ietf-cbor-array-tags@ietf.org
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Date: Sat, 09 Mar 2019 11:39:07 -0800
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Subject: Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03
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> -----Original Message----- > From: CBOR <cbor-bounces@ietf.org> On Behalf Of Laurence Lundblade > Sent: Friday, March 8, 2019 7:44 AM > To: Francesca Palombini <francesca.palombini@ericsson.com> > Cc: cbor@ietf.org; draft-ietf-cbor-array-tags@ietf.org > Subject: Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 > > In addition to what I said before, a deterministic encoding should be > specified (formerly known as canonical) in the specification and that should > probably be network / big endian. I don't know that I agree with this. Most of the machines that I am working with today are little endian machines, from that point of view if such a thing is done then little endian makes more sense. However the fact that these are different tags implies that there is no need to have a deterministic encoding for this. The encoding is going to be deterministic based on which endianness is chosen and that is machine or program specific. I would expect that many implementations would not bother with the big endian encode and might not do the decode as they would be very rarely found. > > To go on a bit more about detailed implementation... > > In a native implementation there is also memory access alignment issue on > the decode side, but not the encode side. Memory alignment is an issue on > some Arm CPUs, though not on Intel CPUs as far as I know. So on some Arm > CPUs, it wonβt be possible to just return pointers to the bytes that came off > the wire. Because non-string and non-aggregate CBOR data items can be 1, 2, > 3, 5 and 9 bytes long, there can be no guarantee of alignment of the incoming > encoded CBOR bytes. > A portable decoder implementation will have to allocate aligned memory for > the array and copy it. The decoder can byte-swap while it is copying so it lines > up OK with the decoder having to do most of the work to achieve interop. I am confused here about what you are saying here. I think you mean that returning a pointer to data block in the encoded structure may be a problem if it is not aligned, but if that is what you are saying I really don't understand that from the above text. Jim > > Thereβs no alignment issue on the encode side. > > The only other thing Iβve encountered in CBOR that needs copying of data is > indefinite length strings. That depends on the internal structure of binary data as well. It may also need to be copied to get correct alignment. > > LL > > > > > On Mar 7, 2019, at 7:15 PM, Laurence Lundblade <lgl@island-resort.com> > wrote: > > > > Comments in my usual veinβ¦ > > > > Because of the big/little endian option, it seems like this needs a discussion > about design protocols with it, about preferred encoding / decoding and > about interop. > > > > Probably it should say decoders should support both big and little and the > encoder can do what is natural. It seems like there might be an option for > both sides to support only one endianness, which will likely often be little > endian because it is common. > > > > LL > > > > > >> On Mar 6, 2019, at 4:53 AM, Francesca Palombini > <francesca.palombini@ericsson.com> wrote: > >> > >> CBOR WG, > >> > >> The chairs believe the array-tags document is ready for WGLC: > >> https://tools.ietf.org/html/draft-ietf-cbor-array-tags-03 > >> > >> The WGLC will end by *20th of March*, please make sure to send your > comments to the list before then. > >> > >> Best regards, > >> Francesca & Barry > >> > >> ο»ΏOn 05/03/2019, 23:58, "CBOR on behalf of Carsten Bormann" <cbor- > bounces@ietf.org on behalf of cabo@tzi.org> wrote: > >> > >> -03 reflects the fact that IANA has made the allocations. > >> > >> From this authorβs point of view, we are ready for WGLC. > >> > >> GrΓΌΓe, Carsten > >> > >> > >>> On Mar 5, 2019, at 23:55, internet-drafts@ietf.org wrote: > >>> > >>> > >>> A New Internet-Draft is available from the on-line Internet-Drafts > directories. > >>> This draft is a work item of the Concise Binary Object Representation > Maintenance and Extensions WG of the IETF. > >>> > >>> Title : Concise Binary Object Representation (CBOR) Tags for > Typed Arrays > >>> Authors : Johnathan Roatch > >>> Carsten Bormann > >>> Filename : draft-ietf-cbor-array-tags-03.txt > >>> Pages : 14 > >>> Date : 2019-03-05 > >>> > >>> Abstract: > >>> The Concise Binary Object Representation (CBOR, RFC 7049) is a data > >>> format whose design goals include the possibility of extremely small > >>> code size, fairly small message size, and extensibility without the > >>> need for version negotiation. > >>> > >>> The present document makes use of this extensibility to define a > >>> number of CBOR tags for typed arrays of numeric data, as well as two > >>> additional tags for multi-dimensional and homogeneous arrays. It is > >>> intended as the reference document for the IANA registration of the > >>> CBOR tags defined. > >>> > >>> > >>> The IETF datatracker status page for this draft is: > >>> https://datatracker.ietf.org/doc/draft-ietf-cbor-array-tags/ > >>> > >>> There are also htmlized versions available at: > >>> https://tools.ietf.org/html/draft-ietf-cbor-array-tags-03 > >>> https://datatracker.ietf.org/doc/html/draft-ietf-cbor-array-tags-03 > >>> > >>> A diff from the previous version is available at: > >>> https://www.ietf.org/rfcdiff?url2=draft-ietf-cbor-array-tags-03 > >>> > >>> > >>> Please note that it may take a couple of minutes from the time of > >>> submission until the htmlized version and diff are available at > tools.ietf.org. > >>> > >>> Internet-Drafts are also available by anonymous FTP at: > >>> ftp://ftp.ietf.org/internet-drafts/ > >>> > >>> _______________________________________________ > >>> I-D-Announce mailing list > >>> I-D-Announce@ietf.org > >>> https://www.ietf.org/mailman/listinfo/i-d-announce > >>> Internet-Draft directories: http://www.ietf.org/shadow.html or > >>> ftp://ftp.ietf.org/ietf/1shadow-sites.txt > >>> > >> > >> _______________________________________________ > >> CBOR mailing list > >> CBOR@ietf.org > >> https://www.ietf.org/mailman/listinfo/cbor > >> > >> > >> _______________________________________________ > >> CBOR mailing list > >> CBOR@ietf.org > >> https://www.ietf.org/mailman/listinfo/cbor > > > > _______________________________________________ > > CBOR mailing list > > CBOR@ietf.org > > https://www.ietf.org/mailman/listinfo/cbor > > _______________________________________________ > CBOR mailing list > CBOR@ietf.org > https://www.ietf.org/mailman/listinfo/cbor
- [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Francesca Palombini
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Jeffrey Yasskin
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Laurence Lundblade
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Carsten Bormann
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Laurence Lundblade
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Jim Schaad
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Jim Schaad
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Laurence Lundblade
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Jim Schaad
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Jeffrey Yasskin
- Re: [Cbor] π WGLC on draft-ietf-cbor-array-tags-03 Jim Schaad