This class implements a connection point.
template< class T, const IID* piid, class CDV = CComDynamicUnkArray > class ATL_NO_VTABLE IConnectionPointImpl : public _ICPLocator< piid >
Your class, derived from IConnectionPointImpl.
A pointer to the IID of the interface represented by the connection point object.
IConnectionPointImpl implements a connection point, which allows an object to expose an outgoing interface to the client. The client implements this interface on an object called a sink.
ATL uses IConnectionPointContainerImpl to implement the connectable object. Each connection point within the connectable object represents an outgoing interface, identified by piid. Class CDV manages the connections between the connection point and a sink. Each connection is uniquely identified by a "cookie."
For more information about using connection points in ATL, see the article Connection Points.