Since the Ball and Socket notation is not well supported in modern tools, the best replacement is the technique I used in Lecture 7 shown on slide 40 and reproduced below. The "ball" get replaced by two classes, one tagged with «Interface» to show what interface is being referenced/used, the second class is the one that is implementing the interface. This is shown via an association that has been tagged with the UML stereotype «implements». The "socket" is then replaced by a simple association between the class that makes use of the interface and the interface itself.
In the diagram below, the "ball" is the pair of classes named DelegateInterface and Delegate and the "socket" is represented by the association between Host and DelegateInterface.
Feel free to ignore the ball and socket notation and just use this one for the rest of the class.
