Robert Wilton's No Objection on draft-ietf-httpbis-header-structure-18: (with COMMENT)

Robert Wilton has entered the following ballot position for
draft-ietf-httpbis-header-structure-18: No Objection

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COMMENT:
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Hi,

Thank you for writing this document.  As per the other comments, more effort to
have a tighter specification of HTTP header fields is likely to be beneficial,
particularly if there are readily usable open source libraries that implement
these.

However, my main comment (which possibly could have been a discuss) questions
how this is specified.  In my experience other specifications of encodings
define exactly what the format the encoding must take, but leave it up to
implementation to decide how to perform that encoding.  Whereas this document
specifies the format in 3 ways: (i) as a prose description of the format, (ii)
as an ABNF description of the format, (iii) as a pair of algorithms that
construct or parse the format.  I would prefer for the ANBF to be definitive
along with prose to describe/refine the ANBF as required.  For the algorithms,
I would have preferred that they are held in the appendix as non-normative text
that provides a description of one possible method of writing the serialization
or parsing code.  The corner cases that the algorithm cover could be in the
normative prose/ABNF description.  I appreciate that this would be a
significant change to the document and hence will leave it to
authors/responsible AD to decide whether to process or ignore this comment.

A few other comments on particular sections that I noted:

1.2.  Notational Conventions

   When parsing from HTTP fields, implementations MUST follow the
   algorithms, but MAY vary in implementation so as the behaviors are
   indistinguishable from specified behavior.

I find that sentence slightly strange in that the first part of the sentence
states that your MUST follow the algorithm, and the second part states that you
don't have to follow the algorithm.  It might be more clear if this was worded
differently.  E.g. MUST have behavior that is indistinguishable from that
produced by the algorithm.

3.1  Lists:

   An empty List is denoted by not serializing the field at all.

This was slightly unclear to me.  Does this mean that it isn't possible to
distinguish between not providing the header and providing an empty list? 
Possibly it might be worth clarifying this here, although I note that it does
become clear what the expected behavior is later in the document.

3.2.  Dictionaries

   Dictionaries are ordered maps of name-value pairs, where the names
   are short, textual strings

"short, textual" => short textual"

It might also be helpful to explicitly state what the ordering is (i.e. I
presume that it is the order that they are listed in the request)

3.3.1 Integers
Are "00" "01" "-0", "-01" all allowed?

3.3.6.  Booleans
Should this cover the fact that if the boolean value is not present it is
interpreted as true in a parameter or dictionary?  E.g. as per the description
in the parameter and dictionaries sections?

Regards,
Rob

Received on Wednesday, 20 May 2020 14:16:18 UTC