| CONTENTS | PREV | NEXT | Java Remote Method Invocation |
Unreferenced
Interface
package java.rmi.server;
public interface Unreferenced {
public void unreferenced();
}
The
java.rmi.server.Unreferenced interface allows a server
object to receive notification that there are no clients holding
remote references to it. The distributed garbage collection
mechanism maintains for each remote object, the set of client
virtual machines that hold references to that remote object. As
long as some client holds a remote reference to the remote object,
the RMI runtime keeps a local reference to the remote object. Each
time the remote object's "reference" set becomes empty
(meaning that the number of clients that reference the object
becomes zero), the Unreferenced.unreferenced method is
invoked (if that remote object implements the
Unreferenced interface). A remote object is
not required to support the Unreferenced
interface.
As long as some local reference to
the remote object exists, it may be passed in remote calls or
returned to clients. The process that receives the reference is
added to the reference set for the remote object. When the
reference set becomes empty, the remote object's
unreferenced method will be invoked. As such, the
unreferenced method can be called more than once (each
time the set is newly emptied). Remote objects are only collected
when no more references, either local references or those held by
clients, still exist.