Answer to Question 1
B
Answer to Question 2
The standard UML icon is a box with two tabs, similar to a plug. Components, however, can also be represented by stereotyped boxes. A component can be modeled both as a black box that hides its internal structure, and as a white box that exposes that structure.
In black-box modeling, we represent the interfaces that the component supports as lines that end in a circle. The outside world can interact with the component only through these interfaces. In turn, if the component requires an external interface in its environment, the requirement is shown as a line ending in a half-circle. This arrangement is often called ball and socket because the interface provided by one component must fit into the socket provided by its client.
In white-box modeling, the internal structure of the component is shown as a diagram inside the stereotyped box that represents the component. The communication between entities inside the box and outside entities takes place through ports, shown as small boxes that are situated on the borders of the component box. An incoming port delegates a provided interface to an object, or another component, inside the component. An outgoing port conveys requests by internal entities to the required interface of an outside component.
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