Archive for the ‘Roles’ Category

Role Modeling

Friday, May 25th, 2012

Role Modeling

From the webpage:

Roles are about objects and how they interact to achieve some purpose. For thirty years I have tried to get them into the into the main stream, but haven’t succeeded. I believe the reason is that our programming languages are class oriented rather than object oriented. So why model in terms of objects when you cannot program them?

Almost all my documents are about role modeling in one form or another. There are two very useful abstractions on objects. One abstraction classifies objects according to their properties. The other studies how objects work together to achieve one or more of the users’ goals. I have for the past 30 years tried to make our profession aware of this important dichotomy, but have met with very little success. The Object Management Group (OMG) has standardized the Unified Modeling Language, UML. We were members of the core team defining this language and our role modeling became part of the language under the name of Collaborations. Initially, very few people seemed to appreciate the importance of the notion of Collaborations. I thought that this would change when Ivar Jacobson came out with his Use Cases because a role model shows how a system of interacting objects realizes a use case, but it is still heavy going. There are encouaging signs in the concept of Components in the emerging UML version 2.0. Even more encouaging is the ongoing work with Web Services where people and components are in the center of interest while classes are left to the specialists. My current project, BabyUML, binds it all together: algorithms coded as classes + declaration of semantic model + coding of object interaction as collaborations/role models.

The best reference is my book Working With Objects. Out of print, but is still available from some bookshops including Amazon as of January 2010.

You can download the pdf of Working with Objects (version before publication). A substantial savings over the Amazon “new” price of $100+ US.

This webpage has links to a number resources from Trygve M. H. Reenskaug on role modeling.

I saw this reference in a tweet by Inge Henriksen.

idk (I Don’t Know) – Ontology, Semantic Web – Cablegate

Sunday, December 5th, 2010

While researching the idk (I Don’t Know) post I ran across the suggestion unknown was not appropriate for an ontology:

Good principles of ontological design state that terms should represent biological entities that actually exist, e.g., functional activities that are catalyzed by enzymes, biological processes that are carried out in cells, specific locations or complexes in cells, etc. To adhere to these principles the Gene Ontology Consortium has removed the terms, biological process unknown ; GO:0000004, molecular function unknown ; GO:0005554 and cellular component unknown ; GO:0008372 from the ontology.

The “unknown” terms violated this principle of sound ontological design because they did not represent actual biological entities but instead represented annotation status. Annotations to “unknown” terms distinguished between genes that were curated when no information was available and genes that were not yet curated (i.e., not annotated). Annotation status is now indicated by annotating to the root nodes, i.e. biological_process ; GO:0008150, molecular_function ; GO:0003674, or cellular_component ; GO:0005575. These annotations continue to signify that a given gene product is expected to have a molecular function, biological process, or cellular component, but that no information was available as of the date of annotation.

Adhering to principles of correct ontology design should allow GO users to take advantage of existing tools and reasoning methods developed by the ontological community. (http://www.geneontology.org/newsletter/archive/200705.shtml, 5 December 2010)

I wonder about the restriction, “…entities that actually exist.” means?

If a leak of documents occurs, a leaker exists, but in a topic map, I would say that was a role, not an individual.

If the unknown person is represented as an annotation to a role, how do I annotate such an annotation with information about the unknown/unidentified leaker?

Being unknown, I don’t think we can get that with an ontology, at least not directly.

Suggestions?

PS: A topic map can represent unknown functions, etc., as first class subjects (using topics) for an appropriate use case.