Setting up the project

To begin, let’s create a simple project structure. We’ll need two Java classes - a server class and a client class.

// Server.java
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.io.InputStream;

public interface Server extends Remote {
    InputStream getInputStream(String filename) throws RemoteException;
}

// ServerImpl.java
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.io.*;

public class ServerImpl extends UnicastRemoteObject implements Server {
    protected ServerImpl() throws RemoteException {
        super();
    }

    public InputStream getInputStream(String filename) throws RemoteException {
        try {
            File file = new File(filename);
            return new FileInputStream(file);
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
}

// Client.java
import java.rmi.Naming;
import java.io.*;

public class Client {
    public static void main(String[] args) {
        try {
            Server server = (Server) Naming.lookup("//localhost/Server");
            InputStream inputStream = server.getInputStream("file.txt");
            // Use the input stream for further processing
            // ...
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Implementing streaming with RMI

To implement streaming in Java RMI, we need to define an interface that extends the Remote marker interface. This interface will include a method for retrieving an InputStream object.

In the example above, the Server interface defines the getInputStream() method, which takes a filename as input and returns an InputStream object. The ServerImpl class implements this interface and provides an implementation for the getInputStream() method by creating a FileInputStream for the given file.

On the client side, the Client class demonstrates how to use the getInputStream() method on the remote server object obtained through RMI. It calls the getInputStream() method on the server object to retrieve the InputStream object, which can be used for further processing, such as reading the stream and performing data operations.

Conclusion

In this blog post, we explored how streaming can be implemented in Java RMI. By creating an interface with a method returning an InputStream, and implementing that interface on the server side, we can provide streaming capabilities over RMI. The client can then retrieve the InputStream to consume the stream for further processing.