A meta model in ConceptBase is a collection of inter-related meta classes.
Its instances are (ordinary classes) subsumed in models.
In the example below, the meta model is displayed on the upper third of the screendump.
It specifies a notation for represented document and
task flows between agents. The greater part of the screendump
shows an excerpt a document flow model instantiated from the meta
model. Note that the document flow is just one aspect of the
meta model. Other aspects like the task flow are represented
in other views.
The graphical display is generated from the class and metaclass
definitions in ConceptBase.
The definitions of meta models and models is done in a simple textual frame syntax. For example, one would define the document flow at the meta class level as:
Agent with
attribute
delivers: Agent
end
Agent!delivers with
attribute
content: Document
end
Document end
This defines a delivery relation between agents. A document is attached to the deliver as its content. At the model level, one instantiates the meta model by simply using its features:
ServicePerson in Agent with
delivers
travelexpensedelivery: Secretary
end
ServicePerson!travelexpensedelivery with
content
document1: TravelExpenseDeclaration
end
You may wonder why some of the agents (=Akteur in German) on the screendump are displayed in red color and others in blue. This is due to the flexible assignment of graphical symbols to objects. The assignment is based on queries. In this case, the 'red' agents are classified by a query that extract those agents who do not receive a document. Hence, some kind of graphical model analysis can be done by proper use of the graphical types. If the properties of an object change by an update to the concept base, its graphical display is adapted as well via a synchronization mechanism of the ConceptBase graph editor.
http://conceptbase.cc -- Contact: M. Jeusfeld, Tilburg University, Postbus 90153, 5000 LE Tilburg, The Netherlands -- 15-Sep-2005