[occi-wg] Typed Link Kind

[Boris Parak]

On Fri, Jul 31, 2015 at 5:01 PM, Jean Parpaillon
<jean.parpaillon at free.fr> wrote:
> Hi Boris,
>
> Le vendredi 31 juillet 2015 à 11:48 +0200, Boris Parak a écrit :
>> Hi Jean,
>>
>> On Fri, Jul 31, 2015 at 10:49 AM, Jean Parpaillon
>> <jean.parpaillon at free.fr> wrote:
>> > Hi all,
>> > With Olivier Barais, in CC, with which I am working on the OCCIware
>> > project, we would like to enhance the core specification with a way
>> > to
>> > constrain the Category of resources pointed out by occi.core.src
>> > and
>> > occi.core.target attributes of a link.
>> >
>> > For instance, in the infrastructure extension, while it is
>> > specified
>> > (and easily make sense) a NetworkInterface link must be linked to a
>> > compute and a network instance, there is no formal way to define
>> > this
>> > constraint.
>> >
>> > A proposal would be to add new type of Category, sub-type of Kind,
>> > with
>> > following attributes:
>> > - parent: instantiated as http://schemas.ogf.org/occi/core#link
>> > - occi.core.src.type: additional attribute, type category id
>> > - occi.core.target.type: additional attribute, type category id
>> >
>> > The name of this type of Category could be "TypedLinkKind".
>> >
>> > What do you think of this ?
>>
>> at first glance, it looks like a reasonable request ... it would
>> definitely improve automated validation and modeling in OCCI.
>> Especially with previously unknown extensions.
>>
>> 'occi.core.target' will be a bit problematic, because it can point
>> "outside" the local domain. But we could easily cover that by making
>> these attributes optional.
>>
>> So, I would consider dropping the TypedLinkKind and include these two
>> attributes in the existing Link kind, as optional. That way we get a
>> typed link, partially typed link and "legacy" link all-in-one. While
>> keeping it all backwards compatible. If the type attribute is
>> present,
>> you can use it, if not ... well ... you are out of luck :-)
>>
>> As a side note, I would very much like to avoid introducing attribute
>> names with matching prefixes:
>>
>> occi.core.target = "value"
>> occi.core.target.type = "value"
>>
>> This makes JSON rendering really difficult. Would you be OK with
>> "target_type" & "source_type"?
>
> I would prefer the former one, but I can accept the second one.

I know ... 'target.type' makes more sense and is much prettier to look at.

> BTW, here is the algortihm I use for inserting any dot-separated
> attribute name into the JSON tree of attributes, would you be
> interested in implementing it into rocci:
> https://github.com/erocci/erocci/blob/master/apps/erocci_core/src/rende
> ring/occi_renderer_json.erl#L194

I have to admit that my basic understanding of functional languages is
a problem here :-)

How do you deal with complex attribute values? Let's say we have an attribute

occi.test.target = { ... Hash Here ... } // hash has "type" =>
"StringHere" inside it

and an attribute

occi.test.target.type = "StringHere"

How would you distinguish between the value for key 'type' in the
attribute value (Hash) of 'occi.test.target' and the attribute value
of 'occi.test.target.type'? How would these be rendered in JSON
together?

Could you give me the rendered JSON as an example?

>
>>
>> Also, could you, please, include this as a comment here [1], then we
>> can discuss it as a part of public comment on OCCI 1.2 and possibly
>> include it :-)
>
> Done, last minute before end of comments ;)
>
>>
>> Thanks!
>>
> You're welcome.
>
> Jean

Cheers, Boris

>> [1] https://redmine.ogf.org/boards/26/topics/429
>>
>> >
>> > Regards,
>> > --
>> > Jean Parpaillon
>> > --
>>
>> Cheers, Boris
>>
>> > Open Source Consultant
>> > OW2 Technology Council Chairman
>> > Director @ OW2 Consortium
>> > OCCIware Strategic Orientation Committee Chairman
>> > Research Engineer @ Inria
>> > --
>> > Phone: +33 6 30 10 92 86
>> > im: jean.parpaillon at gmail.com
>> > skype: jean.parpaillon
>> > linkedin: http://www.linkedin.com/in/jeanparpaillon/en
>> > _______________________________________________
>> > occi-wg mailing list
>> > occi-wg at ogf.org
>> > https://www.ogf.org/mailman/listinfo/occi-wg
> --
> Jean Parpaillon
> --
> Open Source Consultant
> OW2 Technology Council Chairman
> Director @ OW2 Consortium
> OCCIware Strategic Orientation Committee Chairman
> Research Engineer @ Inria
> --
> Phone: +33 6 30 10 92 86
> im: jean.parpaillon at gmail.com
> skype: jean.parpaillon
> linkedin: http://www.linkedin.com/in/jeanparpaillon/en