[occi-wg] Typed Link Kind

[Boris Parak]

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"?

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 :-)

Thanks!

[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
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