Below is a clear, structured, and detailed explanation of RMI: Compiling and Executing the Server and Client, presented in a step-by-step technical manner.

RMI: Compiling and Executing the Server and Client

Introduction

After defining and implementing the remote interface in RMI, the next step is to compile and execute the application. This involves preparing the server, registering the remote object, and running the client to invoke remote methods.

RMI execution follows a multi-step process involving compilation, registry setup, server startup, and client execution.

Components Involved

Remote Interface
Implementation Class
Server Program
Client Program
RMI Registry

Project Files Example

Calculator.java        (Remote Interface)
CalculatorImpl.java    (Implementation)
Server.java            (Server program)
Client.java            (Client program)

Step 1: Compile All Java Files

Use the javac compiler:

javac *.java

This generates .class files for all components.

Step 2: Generate Stub Classes (Optional in Modern Java)

In older versions of Java:

rmic CalculatorImpl

📌 In modern Java (Java 5+), this step is not required because stubs are generated dynamically.

Step 3: Start RMI Registry

The RMI registry acts as a directory service for remote objects.

rmiregistry 1099

Default port: 1099
Must be started before server

📌 Ensure it runs in the same directory as compiled classes.

Step 4: Write and Run Server Program

Server Code Example

import java.rmi.Naming;

public class Server {
    public static void main(String[] args) {
        try {
            CalculatorImpl obj = new CalculatorImpl();
            Naming.rebind("rmi://localhost/CalculatorService", obj);
            System.out.println("Server is ready...");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Run Server

java Server

📌 Server will:

Create remote object
Register it with RMI registry

Step 5: Write and Run Client Program

Client Code Example

import java.rmi.Naming;

public class Client {
    public static void main(String[] args) {
        try {
            Calculator obj = (Calculator) Naming.lookup("rmi://localhost/CalculatorService");
            int result = obj.add(10, 20);
            System.out.println("Result = " + result);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Run Client

java Client

Execution Flow

Compile all Java files
Start RMI registry
Run server → registers object
Run client → looks up object
Client invokes remote method
Server processes request
Result returned to client

Important Points

Server must start before client
Registry must be running
Same interface must be available on both client and server
Network configuration must be correct

Common Errors

Connection refused → Registry not running
NotBoundException → Object not registered
ClassNotFoundException → Missing class files
MalformedURLException → Incorrect URL

Best Practices

Always start registry first
Use correct classpath
Keep interface consistent
Handle exceptions properly
Use meaningful service names

Conclusion

Compiling and executing an RMI application involves multiple coordinated steps, including compiling classes, starting the RMI registry, running the server to register remote objects, and executing the client to invoke remote methods. Proper execution order and configuration are essential for successful communication in distributed Java applications.

Compiling and executing the server and the client