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Re: AW: [higgins-dev] Newbie question: Higgins Ontology (HOWL XML File) to Java Model Classes (EntityModel, AttributeModel) Mapping. How does it work?

Title: Re: AW: [higgins-dev] Newbie question: Higgins Ontology (HOWL XML File) to Java Model Classes (EntityModel, AttributeModel) Mapping. How does it work?
Berend,

We would like to replace the Model interfaces in IdAS entirely for Higgins 1.1 (see [1]). We’re looking for volunteers :)

--Paul

On 7/9/09 5:23 AM, "Berend.Boll@xxxxxxxxxxxxx" <Berend.Boll@xxxxxxxxxxxxx> wrote:

Hi Markus,

thank you for your advice. As you guessed I am thinking about the case 3 in your list, the concrete domain ontology or the schema of the CP. I was confused that there is no "automatic" mapping, when I create a context in Higgins via the Higgins registry, because I saw all the "Model" classes in the Higgins Java code. I will take a look at the special Jena CP for the OWL/RDF handling.

- Thanks
Berend



 

Von: higgins-dev-bounces@xxxxxxxxxxx  [mailto:higgins-dev-bounces@xxxxxxxxxxx] Im Auftrag von Markus  Sabadello
Gesendet: Montag, 6. Juli 2009 20:15
An: Higgins  (Trust Framework) Project developer discussions
Betreff: Re:  [higgins-dev] Newbie question: Higgins Ontology (HOWL XML File) to Java Model  Classes (EntityModel,AttributeModel) Mapping. How does it  work?

 
Hello Berend,

I am not sure exactly what you mean with  "Higgins ontology XML file". There are three things to be distinguished  here:

1. The cdm.owl file in the org.eclipse.higgins.ontology  project.
This is what we call the Higgins "Context Data Model". You can  read about it here:
http://wiki.eclipse.org/Context_Data_Model
It  defines the very basic foundations (Contexts, Entities, Attributes) of our  data model. The cdm.owl file is meant only for documenting purposes. It is  basically an RDF/OWL file describing the same concepts as the above wiki page,  but this file is never used programmatically.

2. The higgins.owl file  in the org.eclipse.higgins.ontology project.
This file is based on the  above "Context Data Model". This is an "upper ontology" which is meant to  serve as a basis for concrete domain ontologies (see next point). It describes  some more advanced features which we actually use programmatically in IdAS.  For example, it describes an access control mechanism, and how to make  statements about attributes (e.g. lastModified, creator, ...)

3. A  concrete domain ontology (aka as the schema of a Context Provider).
Maybe  this is what you referring to. This defines the concrete classes of Entities  and Attributes in a Context Provider, like employee, supplier, e-mail address,  friend, etc. IdAS itself doesn't define these things, it's up to the  individual Context Providers to do this (well, you probably know this  already). Anyway, the point is that therefore Context Providers also have  their own code for implementing the IdAS Model API and returning "models" for  their Entities and Attributes. Some CPs can be very restricted (e.g. allowing  only a few predefined Entity and Attribute classes), whereas others can be  very open (allowing pretty much anything).

If you create your own  Context Provider, I would say that it is good practice - but not required - to  write down its domain ontology in an RDF/OWL file, potentially using some  parts of higgins.owl.

Maybe you have already created such a domain  ontology, and now you want to automatically create Model classes based on it.  Is this what you are asking?

Conceptually I guess this would make  sense. I don't think we have code for automatically "converting" a domain  ontology (expressed in RDF/OWL) to a set of Java classes that can be used for  the IdAS Model API. BUT: We have one Context Provider (the Jena one) which  internally stores its data as RDF. It properly supports the IdAS Model API.  This means that the code in the Jena Context Provider could come very close to  what you are looking for. For example, if you call getAttributeModels() on an  Entity from the Jena CP, it will take a look at its own ontology and return  IdAS Model objects for the RDF Properties it finds.

If this sounds  promising, have a look at the Java package org.eclipse.higgins.idas.model.impl  in the org.eclipse.higgins.cp.jena2 project.

Hope that helps a bit, let  us know if you still have questions..

Markus

P.S. The only  reason why the XMLFile Context Provider doesn't support the IdAS Model API is  that nobody has written it; conceptually it could support it.

 
On Fri, Jul 3, 2009 at 5:02 PM, <Berend.Boll@xxxxxxxxxxxxx> wrote:
 
Dear  Higgins Team,

we are currently looking into the Higgins project as a  base implementation for an IdAS/Context Provider solution for our user  profiles distributed over different application silos.

One key point  we are still having problems with, is the question how to map the Higgins  Ontology (as defined in an XML file) to the actual "Model" classes in the  java code (EntityModel, AttributeModel) that can be accessed via the  "getModel()" method.

For example, the Higgins 1.0 solution for the  XMLFile Context Provider does not implement such a mapping. The "getModel"  method is just not implemented here.

Also I can find no source code  that may do such a "generic" scanning and conversion of the Higgins ontology  XML file. From my partial understanding of Higgins so far, I would think  that this mapping task is similar for each context, because the Higgins  ontology is specified. So I do not have to implement such a mapping for each  context provider, but can reuse some conversion method implemented in the  Higgins framework.

Is that so? And if yes, where is it done? What  code can I reuse, when I write my own context provider?

Any help to  get me on the right direction will be appreciated.


Kind  regards,
Berend Boll
T-Systems Enterprise Services GmbH
Systems  Integration
Project Delivery Unit Telco
IP Products Service &  Network
Berend Boll
IT Systems Architect
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