Gives the fully qualified name of the interface that represents
the role of the UI generated by the marshalled UI factory.
If the client program unmarshals the UI factory and invokes a factory method, the
UI returned by the factory method must implement the role the interface specified by
role.
For a client program to be able to use a UI, the client has to have prior knowledge
of the UI semantics, which is defined by the UI's role type. Thus, for a client
to be able to use a UI, the client must understand the semantics
of the type whose fully qualified name is given in the String
referenced from the role field of that UI's UIDescriptor.
For example, two role types that are defined in the net.jini.lookup.ui
package by the Jini Service UI Specification are MainUI, for a main UI
to a Jini service, and AdminUI, for an administration UI. Other role types
may be defined by the Jini Service UI Specification and by individual Jini service API
specifications.
As the strings referenced from the role field are Java type names, they
are intended to be manipulated by client programs only. They should not be shown to a user.