Java RMI : Remote Method Invocation

Remote Method Invocation (RMI) : It allows an object running in one Java virtual machine (say a client machine)  to invoke methods on an object running in another Java virtual machine (a Server machine).

• Server accepts tasks from clients, runs the tasks, and returns any results. The server code consists of an interface and a class. The interface defines the methods that can be invoked from the client. 
• RMI interface extends the interface java.rmi.Remote, and each method declares java.rmi.RemoteException in its throws clause. 
• Server register its remote objects with RMI's simple naming facility, the RMI registry.
• Client program obtains a stub for the registry on the server's host, looks up the remote object's stub by name in the registry, and then invokes method on the remote object using the stub.
• A Serializable object can be passed to-and-fro Client-Server.
• Source files can be compiled like :
  
  javac -d destDir RMIInterface.java RMIInterfaceImpl.java Client.java

RMI stub : In simple, its a proxy or surrogate which helps in managing invocation of remote objects.