This is Kactus2 extension
API interface
(application programming interface) means the protocol that SW
components use to communicate, in practice it is set of function
calls. Purpose is to increase portability by abstacting the
details of underlying HW. These are a lower level concept than
COM interfaces and cannot appear in HW components. API
interfaces make rather tight coupling between SW components, and
often both the sender and receiver are mapped on the same CPU.
COM interfaces are meant for communication between application
modules, whereas API interfaces are mainly between application
and platform (OS, drivers) and inside the platform.
For example, a SW component could have API interfaces 'lower'
and 'upper'. It requests the 'lower' one, DMA driver,
i.e. calls its functions. At the same, this component 'provides'
the 'upper' interface, MCAPI, i.e. other SW components can call
its functions.