Hello David
Le 28/06/2017 à 23:13, David Neufeld a écrit :
> Not sure how to initiate some discussion on this feature request, but
> will try this list first. In addition, to the text and xml formats for
> metadata it would be great to have a JSON representation as well.
>
Indeed, we even did a little experiment on that a while ago (but it
didn't landed on SIS yet - see below).
> A JSON format would ideally be more concise than the xml
> representation to minimize network traffic at scale. Additionally my
> sense (anecdotally) is developers prefer working with JSON payloads
> over XML when possible. SIS may make a nice addition to our metadata
> extraction processes during ingest of data into the center and JSON
> would likely be a preferred format to work with as part of that process.
>
In our little experiment, we faced the following issues. We didn't
provided answer for them yes, since I through that some initiatives at
OGC or elsewhere were under way:
* What is the best way to handle the case where the same metadata
element (typically a ResponsibleParty) is used in more than one
place? Do we repeat the information, or do we use some link
mechanism? (in XML we can use "xlink:href") I have seen discussion
at OGC about JSON-LD where "LD" stands for "Linked Data", but I'm
not yet familiar with it and do not know if it is applicable to this
situation.
* What is the best way to specify the type of a metadata element when
various subtypes exist? For example a property of type
GeographicExtent can actually contains a GeographicBoundingBox or a
BoundingPolygon. Do we try to guess according which attributes
appear in the JSON document, or do we provide a more deterministic
mechanism?
* Do we have an OGC standard about how to represent ISO 19115 metadata
in JSON? I though that some peoples where working on it, but I do
not know if this work is completed.
With an answer to those questions, I think that JSON reader and writer
would actually be easy to do.
Alternatively, YAML has build-in mechanism for the 2 first questions.
This make me think that YAML would be better suited than JSON for ISO
19115 metadata, but unfortunately YAML is not as popular.
Martin
