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Extending OCCI

Not every provider feature will be captured by OCCI and so for providers who wish to offer specific attributes, types (categories) this documentation will detail how to do so. If a provider only needs to add additional attributes to an existing Resource type defined in OCCI then the following example is how that provider (provider.com) should do so. The example also shows a provider providing a new extension Resource type.

Defining & Naming Extension Attributes

The first aspect to consider is the naming of Attributes. The provider-specific attributes should be named with the following pattern:

<reverse_domain>.<category_term>.<attribute>

e.g.

com.provider.compute.boot_priority

Any reverse domain starting with "occi" must be forbidden and only used be standard OCCI attributes. Only through a specification update can these attributes, beginning with "occi.", be updated.

Defining & Naming Extension Resources

Attributes are associated with a Category and so if an extension to an existing Resource type is required then an associated extension Category should be created. To do the this provider need only create a new Category using a unique scheme URI. The extension cannot have a scheme or a sub-scheme URI starting with "http://schemas.ogf.org/occi". Here is an example of the extension Category that is associated with the previously defined Attribute com.provider.compute.boot_priority

Category: compute; scheme="http://provider.com/occi/resource#"; title="Vendor Compute Resource Extensions"

For further information on Categories please see the wiki page on them

Adding Provider-specific Attributes

Example: Let's say a provider need a few extra attributes to describe a compute resource, in this case the desired boot priority.

GET /compute/vm01
Category: compute; scheme="http://schemas.ogf.org/occi/resource#";
    title="Compute Resource"
Category: compute; scheme="http://provider.com/occi/resource#";
    title="Vendor Compute Resource Extensions"
Attribute: occi.compute.memory=2.0
Attribute: occi.compute.speed=3.8
Attribute: com.provider.compute.boot_priority="harddisk,cdrom"

Registration of Extensions

TODO

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	Versions		Associations		Attachments		Back Links

Version	Version Comment	Created By
Version 8	Made example more consistent	Ralf Nyrén - 08/17/2010
Version 7		Andy Edmonds - 08/16/2010
Version 6		Andy Edmonds - 08/16/2010
Version 5		Andy Edmonds - 08/16/2010
Version 4		Andy Edmonds - 08/16/2010
Version 3		Andy Edmonds - 08/16/2010
Version 2		Andy Edmonds - 08/16/2010
Version 1	Added initial content	Andy Edmonds - 08/16/2010