Type IDs
Interface, class, and user exception Slice types have an internal type identifier, known as the type ID. The type ID is simply the fully-qualified name of each type. For example, the type ID of the Child interface in the preceding example is ::Family::Child. A type ID starts with a leading :: and is formed by starting with the global scope (::) and forming the fully-qualified name of a type by appending each module name in which the type is nested, and ending with the name of the type itself; the components of the type ID are separated by ::.
The type ID of the Slice Object type is ::Ice::Object.
Type IDs are used internally by the Ice run time as a unique identifier for each type. For example, when an exception is raised, the marshaled form of the exception that is returned to the client is preceded by its type ID on the wire. The client-side run time first reads the type ID and, based on that, unmarshals the remainder of the data as appropriate for the type of the exception.
Type IDs are also used by the ice_isA operation.