Object model

While the structural metamodel centers on classes and their static structures, the object diagram metamodel enables the representation of how these classes are instantiated into objects and interact with each other. The Object class in the metamodel represents the instances of a Class from the structural metamodel. Its object attributes are defined using the AttributeLink class, and associations with other classes are established using the LinkEnd class. In BESSER, the object diagram metamodel is primarily utilized for conducting validations or tests on the model. For instance, validating OCL rules over instances of the B-UML model.

Object metamodel

Note

The classes highlighted in green originate from the structural metamodel.

Supported notations

To create an object model, you can use any of these notations:

Why Object Models?

Object models serve several important purposes in the BESSER platform:

  • Validate OCL constraints on concrete instances: By creating specific object instances, you can evaluate Object Constraint Language (OCL) rules against real data to verify that your constraints behave as expected.

  • Test metamodel behavior with specific data: Object models let you exercise your structural model with concrete values, catching design issues early before code generation.

  • Demonstrate expected system state: Object diagrams provide concrete examples of how classes are instantiated and related at runtime, making them valuable for documentation and communication with stakeholders.

Python Code Example

The following example shows how to create object instances from a structural model:

from besser.BUML.metamodel.object import *
from besser.BUML.metamodel.structural import DomainModel, Class, Property, StringType

# Assuming a Person class with name attribute
person_class = Class(name="Person", attributes={Property(name="name", type=StringType)})

# Create an instance
john = Object(name="john", classifier=person_class)
john_name = DataValue(classifier=person_class, attribute=name_attr, value="John")
john.add_slot(AttributeLink(attribute=name_attr, value=john_name))

object_model = ObjectModel(name="TestInstances", instances={john})

Supported Notations (additional)

Object models can be created and manipulated using: