All Handler classes are located in the OnixS::CME::iLink3 namespace.

The typical way of using the Handler is the following:

Create the OnixS::CME::iLink3::SessionSettings object and set the corresponding settings.
Create the OnixS::CME::iLink3::Session object.
Establish the iLink 3 session to the CME Market Segment Gateway (MSGW).
Send and receive application-level SBE messages.
Disconnect the session.