[Gen-art] Genart last call review of draft-ietf-calext-jscalendar-25

Robert Sparks via Datatracker <noreply@ietf.org> Tue, 03 March 2020 21:10 UTC

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Subject: [Gen-art] Genart last call review of draft-ietf-calext-jscalendar-25
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Reviewer: Robert Sparks
Review result: Ready with Issues

I am the assigned Gen-ART reviewer for this draft. The General Area
Review Team (Gen-ART) reviews all IETF documents being processed
by the IESG for the IETF Chair.  Please treat these comments just
like any other last call comments.

For more information, please see the FAQ at


Document: draft-ietf-calext-jscalendar-25
Reviewer: Robert Sparks
Review Date: 2020-03-03
IETF LC End Date: 2020-03-09
IESG Telechat date: Not scheduled for a telechat

Summary: This document has minor issues to address before being published as a
Proposed Standard RFC.

Caveats: I did not carefully verify that the initial registry values (of which
there are many) matched the document text.

Minor issues:

ABNF is used, but there is no reference to RFC 5234. The document shepherd
report implies that the ABNF has not been verified (see item 19 in that report).

The first registry in section 8.4.3 should be explicit that it is a registry
for values of the "@type" property. Right now the reader has to infer that.

It's not stated clearly whether a patch should succeed or fail if the resulting
object doesn't meet this specification's requirements. Side question: if a
patch changes 'updated' (4.1.6) in an object that didn't already have a
'created' (4.1.5), should it fail if it doesn't also result in an object that
has a 'created'? Or is it ok to lose the original creation time information?

The security consideration section only points to section 7 of RFC 3986 for
potential issues related to the URIs that can be carried in this
representation. I don't think that's sufficient. There should be some
discussion (or a pointer to discussions) about the potential for malicious
construction of jscalendar objects containing potentially very large numbers of
URIs in, say, as Link objects (4.2.7). Is there an opportunity for amplified
attacks here? (Especially if these URLs might be automatically referenced by
any client, and even more so if the object is sent from a calendar with a large
number of subscribers.)

Have you considered any tighter integrity checking for (4.2.7) links? Maybe a
checksum property?

It doesn't look like application/jscalendar+json has had a media type review.


Introduction, second sentence: "It" is ambiguous. As written, it could point to
"This document" or "a data model". You sort of mean the later, but I think you
really mean the JSON representation (especially when you say "process"), but
you don't talk about that here.

Introduction, design considerations list, last bullet: This bullet is currently
written as description of the end result, not as a design consideration. Please
restate it to match the rest of the elements in the list.

Last full paragraph on page 2: "unlike most common JSON data representations"
is asserted without data. The document doesn't really need it. I suggest simply
deleting the phrase from the sentence.

I don't expect anything to change at this point, but I do have to point to the
dissonance in the conventions A[] and A[B]. It would have been far less
confusing for A have the same semantic in both cases (preferably value), than
the current situation where it means value for A[], but key for A[B].

1.4.3 last paragraph: You don't need to use MUST in this example - it's not a
requirement on the protocol. I suggest replacing "MUST be" with "is correctly".

In 4.2.5 at 'locationTypes', it would be better to point to the actual registry
than only to RFC4589.

Do you want to say anything about what should happen if the size of a resource
(as represented by 'size' in 4.2.7) doesn't match the actual fully decoded
size? I think you mean for this property to be an informational estimate, and
you should explicitly say the actual size could be quite different.

In 4.2.10, 'american-football""' should be 'american-football"' (one fewer ")

In 4.3.2 at 'byDay', why do you have * symbols around 'An *NDay* object'?

In 4.4.5 at 'scheduleUpdated', do you really want to couple this so tightly to
iTIP? Perhaps you should say "the last time this participant provided an
update" and point to iTIP as how these are typically provided?

Major issues:

Minor issues:

Nits/editorial comments: