$ java -jar java-class-loader.jar -help

usage: Main
 -address <arg>       address to connect (client) / to bind (server)
 -classfile <arg>     filename of bytecode .class file to load remotely
                      (default: Payload.class)
 -classmethod <arg>   name of method to invoke (default: exec)
 -classname <arg>     name of class (default: Payload)
 -client              run as client
 -help                print this message
 -keepalive           keeps the client getting classfile from server every
                      X seconds (default: 3 seconds)
 -key <arg>           secret key - 256 bits in base64 format (if not
                      specified it will generate a new one)
 -port <arg>          port to connect (client) / to bind (server)
 -server              run as server

//Payload.java
public class Payload {
    public static String exec() {
        String output = "";
        try {
            output = "Hello world from client!";
        } catch (Exception e) {
            e.printStackTrace();
        }
        return output;
    }
}

$ java -jar java-class-loader.jar -server -address 0.0.0.0 -port 1337 -classfile Payload.class

Running as server
Server running on 0.0.0.0:1337
Generated new key: TOU3TLn1QsayL1K6tbNOzDK69MstouEyNLMGqzqNIrQ=

$ java -jar java-class-loader.jar -client -address 192.168.1.73 -port 1337 -key TOU3TLn1QsayL1K6tbNOzDK69MstouEyNLMGqzqNIrQ=

Running as client
Connecting to 192.168.1.73:1337
Received 593 bytes from server
Output from invoked class method: Hello world from client!
Sent 24 bytes to server