[occi-wg] JSON Rendering

Feldhaus, Florian florian.feldhaus at gwdg.de
Wed Apr 18 10:10:14 EDT 2012


Ok, if no one complains we'll do it on monday 16:00 CET (14:00 UTC). I suggest we use Skype. If there are no objections, I will log into the occi.wg Skype Account and coordinate the call from there.

Cheers,
Florian

Am 18.04.2012 um 10:41 schrieb Jamie Marshall:

> Both are good for me.
> Jamie
> 
> > To: ijm667 at hotmail.com
> > Subject: RE: [occi-wg] JSON Rendering
> > Date: Wed, 18 Apr 2012 09:19:55 +0200
> > From: ralf at nyren.net
> > CC: florian.feldhaus at gwdg.de; occi-wg at ogf.org
> > 
> > 
> > What about:
> > 
> > - Monday 2012-04-23 at 16:00 CET (14:00 UTC)
> > 
> > or
> > 
> > - Tuesday 2012-04-24 at 16:00 CET (14:00 UTC)
> > 
> > ?
> > 
> > 
> > 
> > regards, Ralf
> > 
> > 
> > 
> > On Tue, 17 Apr 2012 22:15:05 +0200, Jamie Marshall <ijm667 at hotmail.com>
> > 
> > wrote:
> > 
> > > Monday, Tuesday and Friday, at any time, are my best days, Wednesday is
> > 
> > > quite busy and Thursday is out of the question.SincerelyJamie
> > 
> > > 
> > 
> > > 
> > 
> > > From: florian.feldhaus at gwdg.de
> > 
> > > To: ralf at nyren.net
> > 
> > > Date: Tue, 17 Apr 2012 19:59:07 +0000
> > 
> > > CC: occi-wg at ogf.org
> > 
> > > Subject: Re: [occi-wg] JSON Rendering
> > 
> > > 
> > 
> > > I would also like to participate. What date / time would be best for
> > 
> > you?
> > 
> > > For me every day of the week would work.
> > 
> > > 
> > 
> > > --Florian
> > 
> > > 
> > 
> > > Am 17.04.2012 um 21:34 schrieb Ralf Nyren:
> > 
> > > 
> > 
> > >> Good idea, next week should be ok.
> > 
> > >> /Ralf
> > 
> > >> 
> > 
> > >> On Tue, 17 Apr 2012 17:51:04 +0200, Edmonds, AndrewX
> > 
> > >> <andrewx.edmonds at intel.com> wrote:
> > 
> > >> 
> > 
> > >>> Suggestion: are people free for a confcall say next week to review and
> > 
> > >>> finalise the JSON work needed to be completed?
> > 
> > >>> 
> > 
> > >>> Andy
> > 
> > >>> 
> > 
> > >>> -----Original Message-----
> > 
> > >>> From: occi-wg-bounces at ogf.org [mailto:occi-wg-bounces at ogf.org] On
> > 
> > >>> Behalf Of alexander.papaspyrou at tu-dortmund.de
> > 
> > >>> Sent: Thursday, April 05, 2012 3:46 PM
> > 
> > >>> To: ralf at nyren.net
> > 
> > >>> Cc: occi-wg at ogf.org
> > 
> > >>> Subject: Re: [occi-wg] JSON Rendering
> > 
> > >>> 
> > 
> > >>> +1 from me on the separation path. Let's get it proper before it
> > 
> > cannot
> > 
> > >>> be separated anymore.
> > 
> > >>> 
> > 
> > >>> -A.
> > 
> > >>> 
> > 
> > >>> Am 05.04.2012 um 16:43 schrieb "Ralf Nyren" <ralf at nyren.net>:
> > 
> > >>> 
> > 
> > >>>> 
> > 
> > >>>> On Thu, 5 Apr 2012 09:21:52 +0000, "Feldhaus, Florian"
> > 
> > >>>> <florian.feldhaus at gwdg.de> wrote:
> > 
> > >>>>> Hi,
> > 
> > >>>>> 
> > 
> > >>>>> how do we proceed?
> > 
> > >>>> 
> > 
> > >>>> The best thing IMO would be to create a version 1.2 of the HTTP
> > 
> > >>>> Rendering doc and update it so that it is a clear separation between
> > 
> > >>>> Protocol and Data Format. The existing text/occi, text/occi and the
> > 
> > >>>> JSON data formats would then be pluggable modules to this spec.
> > 
> > >>>> 
> > 
> > >>>> The quick way is to continue writing the JSON rendering as a
> > 
> > >>>> standalone HTTP-based OCCI rendering which happens to be quite
> > 
> > similar
> > 
> > >>>> to the HTTP Rendering. Saves time but causes lots of duplication.
> > 
> > >>>> 
> > 
> > >>>>> Following a some responses to your comments:
> > 
> > >>>>> 
> > 
> > >>>>> Am 04.04.2012 um 10:59 schrieb Ralf Nyren:
> > 
> > >>>>> 
> > 
> > >>>>>> On Tue, 03 Apr 2012 14:31:24 +0200, Feldhaus, Florian
> > 
> > >>>>>> <florian.feldhaus at gwdg.de> wrote:
> > 
> > >>>>>> 
> > 
> > >>>>>>> Hi,
> > 
> > >>>>>>> 
> > 
> > >>>>>>> once again I would like to reiterate the JSON rendering. First a
> > 
> > >>>>>>> short overview what Alexander and I think are the main points we
> > 
> > >>>>>>> should
> > 
> > >>>>>>> address:
> > 
> > >>>>>>> - remove all HTTP Rendering specific parts from the JSON rendering
> > 
> > >>>>>> 
> > 
> > >>>>>> Remember that an OCCI rendering (as currently specified) includes
> > 
> > >>>> _both_
> > 
> > >>>>>> protocol and data format at the moment.
> > 
> > >>>>> 
> > 
> > >>>>> That's only partly true. A "pure" JSON rendering can already exist
> > 
> > >>>>> independently from the HTTP Rendering without any trouble in
> > 
> > >>>>> rendering.
> > 
> > >>>> 
> > 
> > >>>> No. Yes.
> > 
> > >>>> 
> > 
> > >>>> Probably a misunderstanding here. An OCCI Rendering is defined as a
> > 
> > >>>> way to manipulate the Core Model. So in theory you could have 2
> > 
> > >>>> different HTTP-based OCCI Renderings with different semantics where
> > 
> > >>>> one happen to be using XML as the data format and the othe JSON for
> > 
> > >>>> example. This is not nice but within the definition.
> > 
> > >>>> 
> > 
> > >>>> So to be complete an OCCI Rendering must both define the protocol and
> > 
> > >>>> whatever data format is used by that protocol.
> > 
> > >>>> 
> > 
> > >>>> This does not prevent us from having a single OCCI HTTP Protocol
> > 
> > >>>> Rendering with pluggable data formats.
> > 
> > >>>> 
> > 
> > >>>>>> I like the idea of having a common HTTP Protocol rendering spec
> > 
> > >>>>>> which the JSON rendering could be built upon though.
> > 
> > >>>>> 
> > 
> > >>>>> I second this and would like to move forward. Any comments on the
> > 
> > >>>>> best strategy? Do we need to create a version 1.2 for the HTTP
> > 
> > >>>>> rendering?
> > 
> > >>>> 
> > 
> > >>>> I believe so yes. It would be mostly backwards compatible though.
> > 
> > >>>> 
> > 
> > >>>>>> However, the current HTTP rendering doc lacks things like e.g.
> > 
> > >>>>>> request parameters in URL which I would say is necessary to have a
> > 
> > >>>>>> sane JSON rendering.
> > 
> > >>>>> 
> > 
> > >>>>> I don't think so. The rendering should be independently of the
> > 
> > >>>>> transport protocol. If I ask your server to send me a file by mail
> > 
> > >>>>> containing the JSON rendering of all resources, that should work as
> > 
> > >>>>> well.
> > 
> > >>>> 
> > 
> > >>>> We are probably using different terminology here. I am referring to
> > 
> > an
> > 
> > >>>> OCCI "rendering". Your statement is 100% true for an OCCI data
> > 
> > format.
> > 
> > >>>> However, a data format is not enough to create an OCCI Rendering.
> > 
> > >>>> 
> > 
> > >>>>>>> - consider using RFC 5988 "Web Linking" for collection information
> > 
> > >>>>>>> (e.g. index, next, previous,…)
> > 
> > >>>>>> 
> > 
> > >>>>>> Gary and I had an email conversation which resulted in a solution
> > 
> > >>>>>> where all info necessary for pagination would end up in the request
> > 
> > >>>>>> URL. I.e.
> > 
> > >>>>>> basically eliminating the need for using special headers (such as
> > 
> > >>>>>> RFC 5988).
> > 
> > >>>>>> 
> > 
> > >>>>>> The request parameters to a collection simply allow you to specify
> > 
> > >>>>>> the amount of resource instances you want returned either _before_
> > 
> > >>>>>> or
> > 
> > >>>> _after_
> > 
> > >>>>>> a specific occi.core.id.
> > 
> > >>>>> 
> > 
> > >>>>> Do you have some examples? IMHO this should go to the revised HTTP
> > 
> > >>>>> rendering document.
> > 
> > >>>> 
> > 
> > >>>> The mail thread was on occi-wg so should be in the archives.
> > 
> > >>>> 
> > 
> > >>>> Agree that it would be best to put this into a 1.2 version of the
> > 
> > HTTP
> > 
> > >>>> Rendering doc.
> > 
> > >>>> 
> > 
> > >>>>>>> Examples:
> > 
> > >>>>>>> http://pastebin.com/ZK9Uf0K1 (Entities)
> > 
> > >>>>>> 
> > 
> > >>>>>> Nice, I like that you keep the "attributes" hash now ;)
> > 
> > >>>>>> 
> > 
> > >>>>>> How do you render Link attributes for the links tied to an OCCI
> > 
> > >>>> Resource?
> > 
> > >>>>> 
> > 
> > >>>>> In the example you can see Links are rendered as a hash containing
> > 
> > >>>>> href and kind. The only really necessary part is the href location.
> > 
> > >>>> Everything
> > 
> > >>>>> else is optional and could be retrieved by the client using separate
> > 
> > >>>> HTTP
> > 
> > >>>>> requests. It would also be possible to omit the hash and just render
> > 
> > >>>>> all link hrefs in an array. To allow for a slim rendering and also
> > 
> > >>>>> allow for additional information to be send to the client, I would
> > 
> > >>>>> suggest that we specify a hash with at least the href and optional
> > 
> > >>>>> all other parameters valid for the link. We could even go so far as
> > 
> > >>>>> to use the link rendering for rendering link attributes within
> > 
> > >>>>> resources.
> > 
> > >>>> 
> > 
> > >>>> After many long discussions it was decided to have inline rendering
> > 
> > of
> > 
> > >>>> Link attributes in the OCCI HTTP Rendering. I think the same should
> > 
> > >>>> apply to JSON.
> > 
> > >>>> 
> > 
> > >>>>>>> To keep the mail short, a detailed discussion can be found in the
> > 
> > >>>>>>> attached text document.
> > 
> > >>>>>> 
> > 
> > >>>>>> Just picking out one thread:
> > 
> > >>>>>> 
> > 
> > >>>>>>> resources and links should be represented differently. The entry
> > 
> > >>>>>>> "links" is unique for resources and the entries "target" and
> > 
> > >>>>>>> "source"
> > 
> > >>>>>>> are unique for links.
> > 
> > >>>>>> 
> > 
> > >>>>>> Sounds goods. So the top-level hash of the collection format would
> > 
> > >>>>>> have one hash "resources" and another hash "links" then?
> > 
> > >>>>>> I mean, we still have to cover the case where the client asks for
> > 
> > >>>>>> "everything" at the top-level URL and thus gets both Resources and
> > 
> > >>>> Links
> > 
> > >>>>>> in the response.
> > 
> > >>>>> 
> > 
> > >>>>> I would suggest to have a content-type for entities. It should
> > 
> > >>>>> contain a hash with "links" and "resources". Both then are arrays of
> > 
> > >>>>> hashes.
> > 
> > >>>> 
> > 
> > >>>> I rather have a single array, it plays much better with the
> > 
> > collection
> > 
> > >>>> concept of REST.
> > 
> > >>>> 
> > 
> > >>>>>>> In OCCI Core the attribute names should be changed from
> > 
> > >>>>>>> occi.core.source and occi.core.target to just source and target,
> > 
> > as
> > 
> > >>>> both
> > 
> > >>>>>>> are representing connections to other resources from within the
> > 
> > >>>>>>> OCCI model (similar to links in resources, or kind in entity).
> > 
> > >>>>>> 
> > 
> > >>>>>> occi.core.source and occi.core.target was named simply
> > 
> > source/target
> > 
> > >>>>>> up until just before the OCCI HTTP Rendering doc was published.
> > 
> > >>>>>> 
> > 
> > >>>>>> The fundamental problem here is that we have two different sorts of
> > 
> > >>>>>> "attributes".
> > 
> > >>>>>> 1. Attributes as part of the OCCI Core model. These include both
> > 
> > >>>>>> Entity.id, Entity.title, Resource.summary, Resource.links,
> > 
> > >>>>>> Link.target, Link.source, etc 2. Attributes as exposed by an OCCI
> > 
> > >>>>>> rendering. The HTTP Rendering exposes id, title, summary as
> > 
> > >>>>>> attributes as well as target and source.
> > 
> > >>>>>> However the Resource.links attribute is not exposed as an
> > 
> > >>>>>> attribute...
> > 
> > >>>>>> 
> > 
> > >>>>>> There is no clear distinction here which IMO leads to confusion.
> > 
> > >>>> 
> > 
> > >>>> No comments on the above?
> > 
> > >>>> 
> > 
> > >>>>>> Also remember that a subclass of OCCI Link may have Link.target
> > 
> > >>>> pointing
> > 
> > >>>>>> at some arbitrary external object.
> > 
> > >>>>> 
> > 
> > >>>>> In my opinion, source and target always point to resources, even if
> > 
> > >>>>> they lie outside the OCCI model. They contain complex data types
> > 
> > like
> > 
> > >>>>> kind or mixin and not primitive data types like id, title or
> > 
> > summary.
> > 
> > >>>> 
> > 
> > >>>> So, to link to a VNC console you would have the vnc:// URL where? In
> > 
> > a
> > 
> > >>>> VNC console Resource object?
> > 
> > >>>> 
> > 
> > >>>> /Ralf
> > 
> > >>>> _______________________________________________
> > 
> > >>>> occi-wg mailing list
> > 
> > >>>> occi-wg at ogf.org
> > 
> > >>>> https://www.ogf.org/mailman/listinfo/occi-wg
> > 
> > >>> -------------------------------------------------------------
> > 
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> > 
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> > 
> > >>> Registered Number: E902934
> > 
> > >>> 
> > 
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> > > 
> > 
> > > 
> > 
> > > _______________________________________________
> > 
> > > occi-wg mailing list
> > 
> > > occi-wg at ogf.org
> > 
> > > https://www.ogf.org/mailman/listinfo/occi-wg

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