olemus
UML-liidese tüüp, millega esitatakse rakendamise sõltuvus klassifikaatorist ringina (kuulina) ja kasutuse sõltuvus poolringina (pesana)
the type of UML interface in which the implementation dependency from a classifier to the provided interface is displayed as a circle (ball) and the usage dependency from a classifier to the required interface is displayed as a half-circle (socket)

näiteid
https://www.webel.com.au/sites/default/files/media/slide/2057/uml101%20-%20required_provided%20Interface%20notation%20-%20Ball-and-Socket%20dependency%20wiring.png