| Re: [higgins-dev] Which ontology to reference |
Paul,
Thanks. That makes it more clear. But now I am confused by the relationship of HOWL to IdAS. IdAS only returns Entities.
## This is all a bit hard to understand. In IdAS things are called Entities. In RDF things are called resources. The difference is that in RDF things are identified by HTTP URI identifiers (only), whereas in IdAS (well, the Context Data Model) things are identified by UDIs (more abstract identifiers). As a result we can only approximate Entities using RDF. The fundamentals are different.
## However there is a lot of utility in the existing RDF/OWL tools. So in order to make it easier to use the off the shelf RDF/OWL tools (such as the SWOOP and Protégé that you mentioned), in Higgins 1.1 we split higgins.owl into higgins.owl (which describes new OWL classes like Agent, Group, etc.) and cdm.owl that describes the “meta” model of Entities interconnected with UDIs.
## The latter, cdm.owl is really only for humans to look at. It uses RDF to describe the more abstract foundation (Entities and UDIs) in a shallow way even though RDF-based tools can’t more deeply operationalize the definitions.
In order to build an ontology for my context provider that uses the HOWL objects, it appears I will need to add the Agent object (as well as other objects types) to my own exstension of the CDM, in order to treat the Agent objects as Entities. Is that the correct approach for building the schema for a context provider?
## No. As mentioned above cdm.owl should not be imported into your ontology or used at all when building ontologies. Just import higgins.owl and define your own subclasses and properties. Let’s say that you define a subclass, Foo, of the Agent class in higgins.owl. If you go ahead and implement your ontology in an IdAS Context Provider, this CP may well return an instance of Foo<-- this Foo instance would be a java class that implements the IEntity interface [1]. But unlike in Higgins 1.0 your Foo class (in your ontology) is NOT a subclass of a class named “Entity”.
## HTH, Paul
[1] http://download.eclipse.org/technology/higgins/downloads/idas.api/builds/S-S20090325-200903251303/javadoc/org/eclipse/higgins/idas/api/IEntity.html
Thanks,
David
David Kuehr-McLaren
Tivoli Security
919.224.1960
Paul Trevithick <ptrevithick@xxxxxxxxx>
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SubjectRe: [higgins-dev] Which ontology to reference
Hi David,
That was confusing indeed! I have replaced the word “Entity” in the second sentence with the word “Agent.”
[All classes (including Agent) and instances thereof in higgins.owl 1.1 are types of Higgins Entities. But when modeling in OWL we don’t directly use Entity directly. ]
--Paul
On 4/9/09 3:48 PM, "David Kuehr-McLaren" <dkuehrmc@xxxxxxxxxx <dkuehrmc@xxxxxxxxxx> > wrote:
I am having trouble understanding the instructions to Context Provider authors regarding extending the higgins ontology as per the Context Data Model 1.1 page. (I apologize in advance, if this is a basic OWL question or is documented elsewhere on the wiki)
http://wiki.eclipse.org/Context_Data_Model_1.1#Building_on_higgins.owl_1.1 <http://wiki.eclipse.org/Context_Data_Model_1.1#Building_on_higgins.owl_1.1>
In the section "Building on higgins.owl 1.1 " it states
" Developers must create specialized ontologies based on HOWL that describe specific concrete domains.For example, if a developer wanted to describe a CRM database, she would create an OWL ontology that would describe the data objects in the CRM database. This CRM database is called a Context in Higgins. If, for example, the database contained records about customers and those customers had full-names and email addresses, then the developer would define "Customer" as a sub-class of Entity and "full-name" and "email" as kinds of Attributes."
The first sentence implies the developer should be using the "upper" ontology higgins1.1 owl. But the last sentence tells the developer to reference the CDM and subclass Entity. Intuitively, I think i would want to subclass Person from HOWL for a Customer object. But Agent does not seem to subclass Entity.
When I use OWL modeling tools like SWOOP or Protoge, I can not figure out how to subclass Agent as an Entity.
Thanks for any guidance,
David
David Kuehr-McLaren
Tivoli Security
Identity Integration Architecture
919.224.1960
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