UML/BPMN Metamodel

Objects diagrams are used to provide instance models of classifiers (classes, components, etc.).

They can be created in the context of a classifier (internal structure of a class) or collaboration, and also under a package.

You can create an instance model to represent existing instances, and then abstract them as classes. You can also illustrate a class model by providing a typical instance configuration: in that case classes and attributes pre-exist to instances.

Under a classifier, the object diagram represents parts of the classifier : generally, composite diagrams which show ports and connectors are preferred in this case.