[occi-wg] Categories and Collections

alexander.papaspyrou at tu-dortmund.de alexander.papaspyrou at tu-dortmund.de
Thu Oct 7 03:47:50 CDT 2010

Although I see the threat Gary sketched, I don't think this is a serious problem. OCCI core is clearly designed in a way that you use a category for describing the specifics of a resource. That is, for infrastructure, there will be the ominous ComputeResource category which defines certain attributes for this very type of "thing".

Of course a provider can come up with the stupid idea to leave the "os" field in such a category empty, and rather attach a tag called "SuperOperatingSystemOneDotFive" to it, but this really bends over the spec in a way that you can safely assume the implementor *wants* to break things...

Just my thoughts, though...


Am 07.10.2010 um 09:46 schrieb Gary Mazz:

> Great work adding tags into the collections.
> Adding tags may be  two edged sword. They allow "folksonomy" a path into 
> occi, but tags may be used by providers to represent technical aspects 
> of their infrastructure. This could be catastrophic for 
> interoperability. For example, a provider elects to use tags to 
> represent an OS instead of a template. As/if this practice continues, we 
> may end up with tags de jour, crippling interoperability and devaluing 
> formalized extensions.
> We can minimize the impact by limiting tag usage to informative 
> metadata, not impacting resource provisioning or operations. This would 
> encourage providers to use extensions and provide a taxonomy for 
> extension impacting interoperability.
> -gary
> On 10/6/2010 4:11 AM, Ralf Nyren wrote:
>>> - Could we have some HTTP-rendering examples of how to add/remove Kind
>>> instances to/from a collection other than the defining collection?
>>> AE: I'll get some examples added asap.
>> Good, I just want to make sure the add/remove collection tag thing does
>> not end up with the same problems as we had with Links in the past.
>>> AE: Ooops my mistake - Actions should not have been mentioned (I'll make
>>> that edit). Paging through collections should be accomplished using Links
>>> (e.g. in HTTP header renderings) as you point out. A beginning example
>>> can
>>> be found here [1] in section We need to make sure that the
>>> current
>>> incarnation of Links can accommodate this behavior.
>> Implementing navigation using Link Headers should be easy, we can grab
>> that part directly from the RFC and it will not conflict with the OCCI
>> specific use of Link Headers.
>> Regarding confusing terminology could we be _very_ consistent on using
>> "Link Header" when we refer to RFC5988 and just "Link" when referring to
>> the OCCI base type?
>> I think we should at least consider renaming the OCCI Link base type to
>> something else because the current situation will confuse people.
>>> AE: we could use something like
>>> "http://schemas.ogf.org/occi/core/collections#" as the scheme for tags?
>> We could but Alex point of keeping the namespace clean is also important.
>> Not sure which is best. Will there be only one Category for the collection
>> stuff or will there be more (defined by Core) in the future?
>> Speaking of user defined collections. How is the mix-in attribute
>> occi.core.tag supposed to work when a user adds a Resource instance to 2
>> or more collections?
>> regards, Ralf
>>> I will annotate the wiki page as well.
>>> regards, Ralf
>>> [1] http://forge.ogf.org/sf/wiki/do/viewPage/projects.occi-wg/wiki/Link
>>> On Sun, 03 Oct 2010 17:16:57 +0200, Andy Edmonds<andy at edmonds.be>  wrote:
>>>> Hey all,
>>>> I've placed a write up of how categories and collections related to each
>>>> other. Also there is how one can interact with collections. I've tried
>>>> to
>>>> keep the description as non-rendering-specific as possible.
>>>> http://forge.ogf.org/sf/wiki/do/viewPage/projects.occi-wg/wiki/Collections
>>>> If there are comments etc please annotate the wiki page at the
>>>> appropriate
>>>> place or place your questions in the "Open Issues" section.
>>>> Andy
>>>> andy.edmonds.be
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