When does RMI create sockets

Question

Hi
Is the following sentence correct: "Creating an instance of a class that extends UnicastRemoteObject does not create any sockets. Creation of sockets is not done before the instance is registered with a Registry".
Soeren Mors

Answer 1

From the RMI FAQ:
http://java.sun.com/products/jdk/1.2/docs/guide/rmi/faq.html#connection
F.1 At what point is there a "live" connection between the client and the server and how are connections managed?
When a client does a "lookup" operation, a connection is made to the rmiregistry on the specified host. In general, a new connection may or may not be created for a remote call. Connections are cached by the RMI-transport for future use, so if a connection is free to the right destination for a remote call, then it is used. A client cannot explicitly close a connection to a server, since connections are managed at the RMI-transport level. Connections will time out if they are unused for a period of time.
F.5 Is there only one socket connection between a client process and the server, no matter how many stubs exist in that client process?
RMI reuses the socket connections between client and server whenever possible. The current implementation creates additional sockets on demand when they are needed. For example, if the existing socket is in use by a call then a new socket is created for the new call. Typically, there are at least two sockets open since the distributed garbage collector needs to make remote calls when remote objects are returned from the server. If a cached connection remains unused for a period of time, the connection is closed.