Subject: [Cbor] Review of draft-jroatch-cbor-tags -07

From: Jim Schaad <[email-masked]>
Date: Fri, 9 Mar 2018 14:52:51 -0800

1.  I still have a preference to use a byte of the encoded field to hold the
type information rather than assign lots of tags, but that is going to be
what it is.

2.  The language in 3.1 implies that a multi-dimension array may be of types
other than TypedArray items.  An example of this is in order so that it is
made explicit just how it works.  

3.  In section 3.1 - not sure if there needs to be the ability to have
column major rather than row major arrays.  Fortran is not popular, but
neither is it dead.

4.  In section 3.2 - I assume that the element that is homogenous does not
need to be a primitive type.  An example of this might be useful.
Interesting questions about things like

<Tag TBD41> 
    82  # array(2)
       82  #  array(2)
             F5  # true
             03  # 3
       82 # array(2)
             F5 # true
             23  #  -4 (I think)

This would make to a C structure of  <bool, int32> but is not homogenous in
terms of the CBOR encoding.

5.  It would be good to tell IANA if the values that are being left open are
to be available for other purposes or are reserved as a "just in case" to
deal with the f=1, s=1 case of typed arrays.

6.  It might be reasonable to add a security consideration about dealing
with large items where the size is not known in advance.  There may be
problems with overflows and allocations if one is not careful.

---

From: "Paul Hoffman" <[email-masked]>
Date: Tue, 13 Mar 2018 11:54:30 -0700

I too have reviewed this. My main comment is not as specific as Jim's.

The endianness is going to be done wrong regardless of what you say, but 
we can cause it to be done more right with more use of MUST-filled 
language. The last paragraph in Section 2.1 particularly concerns me.

Other than that, I think the document is in good shape, and it is quite 
understandable.

--Paul Hoffman

---

From: Francesca Palombini <[email-masked]>
Date: Thu, 15 Mar 2018 10:38:33 +0000

Thank you Jim and Paul for your reviews!

Francesca

> -----Original Message-----
> From: CBOR [mailto:[email-masked]] On Behalf Of Paul Hoffman
> Sent: den 13 mars 2018 19:55
> To: [email-masked]
> Cc: [email-masked]
> Subject: Re: [Cbor] Review of draft-jroatch-cbor-tags -07
> 
> The endianness is going to be done wrong regardless of what you say, but we
> can cause it to be done more right with more use of MUST-filled language.
> The last paragraph in Section 2.1 particularly concerns me.
> 
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