W3C home > Mailing lists > Public > public-linked-json@w3.org > August 2011

Spec review/pull request

From: Markus Lanthaler <markus.lanthaler@gmx.net>
Date: Tue, 30 Aug 2011 18:49:30 +0200
To: <public-linked-json@w3.org>
Message-ID: <002e01cc6734$ca596bc0$5f0c4340$@lanthaler@gmx.net>
Hi all,

Over the weekend I've reviewed the spec made a number of changes to it. I've
already sent a pull request and I've also annotated most of the changes in
one of the commits on GitHub since it's too much to be explained in a mail:


Nevertheless I would like to explain some of the changes here and add a few
further possible enhancements.

In section 2.1 Goals and Rationale "streaming" is mentioned. How should that
work? What's the motivation? What are the use cases? If we leave that in the
spec we should elaborate this a bit.
What are the *three* keywords a developer needs to know for JSON-LD (2.1
Simplicity). Should we list them there?

In section 2.2 Linked Data we start talking about
subjects/properties/objects without mentioning triples. This might be a bit
confusing as there is no need to distinguish subjects from objects if you
don't mention that it's serialized in the form of SPO triples.
I'm also not 100% convinced if we should talk about
subjects/properties/objects at all. Properties are normally referred to as
predicates and there is some ambiguity when talking about "objects" since
there also exist JSON objects. Talking about entities/attributes/values
might avoid some of the possible confusion.
I would also propose to add a little figure showing a graph to this section
to illustrate the underlying data model.

In section 2.3 Linking Data it is mentioned "good Linked Data". What's good
Linked Data? What's bad Linked Data?

I've merged sections 2.4 The Context and 2.4.1 Inside a Context as I found
it rather difficult to understand it the way it was. There was no logical
thread and quite a few repetitions.
I would also propose to change, e.g., the "avatar" key to "image" so that
not all JSON terms map directly to a term in a Web Vocabulary as this might
generates wrong assumptions.

In Section 2.5 From JSON to JSON-LD: Shouldn't we mention that the subject
is missing and that this example will result in an blank node?

I think Section 3.1 IRIs should be elaborated. The first list, and there
especially point 1, is not really clear to me. How do we distinguish between
IRIs in keys and terms that are not IRIs?

In section 3.11 Framing: is the output always automatically compacted? If
so, we should mention that.

In section 3.1 CURIEs there is written "the @vocab mechanisms is useful to
easily associate types and properties with a spec. vocabulary". Shouldn't
that be @context?

I've changed the API interface in section 5. The Application Programming
Interface so that all methods have a nullable context parameter. In
compact() it wasn't nullable before but nothing prevents a user to have the
context specified inline (in input). On the other hand it might be useful to
be able to pass a separate (potentially additional) context to the expand(),
frame(), normalize(), and triples() functions.
I've also changed the capitalization from JSONLDProcessor to JsonLDProcessor
to make it more readable. Feel free to revert this.

In section 6.3 Context list item 3.2: @vocab value MUST be an absolute IRI,
why do we need to perform IRI expansion then?

In section 6.3.2 Initial Context "Processors MAY provide means of setting
the base IRI programatically" - shouldn't that MAY be SHOULD?

In section 6.9.1 Compaction Algorithm: Is the first step really to perform
the Expansion Algorithm? If that's really what's intended (it somehow makes
sense) we should describe in one or two sentences why.

In section 6.12 Data Round Tripping. Why is a double normalized to "%1.6e"?
Is there a special reason or was this just arbitrarily defined?

Is Appendix C Mashing Up Vocabularies really needed? That's already
described in the spec. If we really decide to leave it in the spec we should
at least include the context in the first example.

After reading the spec I've also come up with a number of questions and
proposals which I will send in separate mails. This mail is already to long
so that I fear no one will actually read it anyway :-P


Markus Lanthaler
Received on Tuesday, 30 August 2011 16:49:59 UTC

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