Explain the steps to create RMI based clients and server. Explain the various methods for registering and gaining access to the Remote Object.

To create Java RMI Application following steps are needed

• Step 1 - Define the Remote Interface
• Step 2 - Develop the Implementation Class or Remote Object
• Step 3 - Develop the Server Program
• Step 4 - Develop the Client Program
• Step 5 - Compile the Application
• Step 6 - Execute the Application

Step 1 - Define the Remote Interface

• A remote interface provides describes all the methods of a particular remote object.
• The client communicates with this remote interface.
• To create a remote interface −
• Create an interface that extends the predefined interface Remote which belongs to the package.
• Declare all the business methods that can be invoked by the client in this interface.
• Since there is a chance of network issues during remote calls, an exception RemoteException may occur; throw it.

Step 2 - Develop the Implementation Class or Remote Object

• Implementation Class or Remote Object can be written separately or can be written directly with the server program implementation.
• To develop an implementation class −
• Implement the interface created in the previous step.
• Provide implementation to all the abstract methods of the remote interface.

Step 3 - Develop the Server Program

• An RMI server program should implement the remote interface or extend the implementation class. To develop a server program −
• Create a client class from where you want to invoke the remote object.
• Create a remote object by instantiating the implementation class as shown below.
• Export the remote object using the method exportObject() of the class UnicastRemoteObject which belongs to the package java.rmi.server.
• Get the RMI registry using the getRegistry() method of the LocateRegistry class which belongs to the package java.rmi.registry.
• Bind the remote object created to the registry using the bind() method of the class Registry. To this method, pass a string representing the bind name and the object exported, as parameters.

Step 4 - Develop the Client Program

• Write a client program, fetch the remote object and invoke the required method using the remote object. To develop a client program −
• Create a client class from where your are intended to invoke the remote object.
• Get the RMI registry using the getRegistry() method of the LocateRegistry class which belongs to the package java.rmi.registry.
• Fetch the object from the registry using the method lookup() of the class Registry which belongs to the package java.rmi.registry.
• To this method, you need to pass a string value representing the bind name as a parameter. This will return you the remote object.
• The lookup() returns an object of type remote.
• Finally, invoke the required method using the obtained remote object.

Step 5 - Compile the Application

Compile the application in the following manner

• Compile the Remote Interface.
• Compile the Implementation Class.
• Compile the Server Program.
• Compile the Client Program. Or,
• Open the folder where you have stored all the programs and compile all the Java files.

Step 6 - Execute the Application

• Step 1 - Start the RMI registry using the command. start rmiregistry This will start an RMI registry in a separate window.
• Step 2 − Run the server class file java Server
• Step 3 − Run the client class file java Client