RMI

Question 1

What does RMI do?

Answer 1

Allows an object in one VM to invoke methods on another object in another VM (potentially on another physical machine on the network).

Question 2

What are the 3 things you must consider when aming Distributed Object applications?

Answer 2

Remote Object Location
Remote Object Communication
Accessing Class Definitions

Question 3

What is Remote Object Location?

Answer 3

Server application registers the remote objects with the RMI registry
or
pass remote object references via invocations of methods on other objects.

Question 4

What is RMI registry?

Answer 4

Relates remote objects with names

Question 5

What is RMI server?

Answer 5

Calls the registry to associate a name with a remote object
bind() and rebind() - Naming class and registry interface.

Question 6

What is RMI client?

Answer 6

Looks up a remote object by its name in the servers registry and then invokes a method on it.

Question 7

How can an object act as remote?

Answer 7

The object must implement an interface which extends the java.rmi.Remote interface.
Each method in the interface must declare that it throws java.rmi.RemoteException.

Question 8

What are the 3 class loaders used by a JVM

Answer 8

Bootstrap class loader- loads core java libraries, part of the JVM itself
The extensions class loader- loads from system-wide, platform specific extension directory.
The system class loader, loads from the current directory and any specified in the CLASSPATH environment variable of a system.

Question 9

4 layer RMI architecture

Answer 9

Application layer- the client and server program
Stub and Skeleton layer- intercepts method calls made by the client/redirects them to a remote RMI service
Remote reference layer- understand how to interpret and manage references made from clients to remote service objects
Transport layer- based on TCP/IP connections between machines