Network Router User Manual

208 GINA V4.0 System Administrator Guide – September 2000
Glossary
persistent
A persistent object, unlike a →transient object, has a life span which does not depend
on a process. In contrast to this, the life span of a transient object is limited by the life
span of its process.
polymorphy
In object-oriented languages, a derived class inherits the interface of its base class(es).
Polymorphy is when an object of the derived class can be used instead of an object of
a base class.
In C++ we use C++ references and C++ pointers here. A pointer to a base class can
refer to an object of a derived class. In order to call a method of the derived class in this
case, it must already be declared as virtual in the base class. The method is then linked
dynamically at runtime, depending on the current object (
dynamic binding).
proxy
see →stub
reference
1. An alias for an object is called a reference in C++. If you access a reference, you
actually access the referenced object. The reference is thus used in the same way
as an object, from the syntactic point of view.
2. The ODMG uses the term reference to refer to →smart pointers, which are used to
access a persistent object by dereferencing it. In C++, a reference of this kind, like
a pointer, is dereferenced using the operators -> and *. Persistency Service uses
local references P Mibs::MibsRef to access local persistent objects, and T-ORB
uses →global references to address remote objects.
referential integrity
Referential integrity relates to the relations between objects. With the exception of the
→0 reference, an object can only contain references to an existing object. An object
which is deleted can no longer be referenced by another object. Persistency Service
and Database systems can monitor referential integrity.
remote call
A remote call, i.e. a call between two processes (generally on different machines) is
implemented by sending and receiving messages.