A port is both a connectable element and a structural feature of an encapsulated classifier. A port specifies the way a classifier interacts with its external environment or the way the internal environment of the classifier provides services to its external environment. A port may be connected directly to other elements in its external environment but typically uses interfaces to declare either the services that it provides or the services that it requires. A port can be connected to the internal environment of the classifier by connectors. The connectors forward incoming requests to elements in the internal environment or outgoing requests to the ports.
A port is a mechanism for specifying how a classifier interacts with its environment and can be used to make a classifier a replaceable part of a model. A port may specify either the services that a classifier provides to its environment or the services that it requires from its environment. It is a point of interaction between the internal environment of a classifier and its external environment.