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package examples;
import simulator.*;
import core.*;
import prefs.*;
import events.*;
import events.internal.*;
import events.implementations.*;
import serialize.VSSerialize;
import java.io.*;
/**
* Creates a simple working Raft simulation.
* The key insight: Raft protocol uses HAS_ON_SERVER_START, so when servers
* are activated via VSProtocolEvent, the protocol's onServerStart() method
* will be called automatically.
*/
public class CreateSimpleRaftSimulation {
private static final String RAFT_PROTOCOL = "protocols.implementations.VSRaftProtocol";
public static void main(String[] args) throws Exception {
// Initialize
VSDefaultPrefs prefs = new VSDefaultPrefs();
prefs.fillWithDefaults();
VSRegisteredEvents.init(prefs);
// Create frame and simulator
VSSimulatorFrame frame = new VSSimulatorFrame(prefs, null);
VSSimulator simulator = new VSSimulator(prefs, frame);
frame.addSimulator(simulator);
// Access visualization via reflection
java.lang.reflect.Field vizField = VSSimulator.class.getDeclaredField("simulatorVisualization");
vizField.setAccessible(true);
VSSimulatorVisualization viz = (VSSimulatorVisualization) vizField.get(simulator);
// Add more processes - we want 5 total (3 servers, 2 clients)
while (viz.getNumProcesses() < 5) {
java.lang.reflect.Method addProcessMethod = VSSimulatorVisualization.class.getDeclaredMethod("addProcess");
addProcessMethod.setAccessible(true);
addProcessMethod.invoke(viz);
}
VSTaskManager taskManager = viz.getTaskManager();
// Activate Raft SERVERS on processes 0, 1, 2
// Since Raft uses HAS_ON_SERVER_START, onServerStart() will be called automatically!
System.out.println("Creating Raft server activations...");
for (int i = 0; i < 3; i++) {
VSProtocolEvent serverEvent = new VSProtocolEvent();
serverEvent.setProtocolClassname(RAFT_PROTOCOL);
serverEvent.isClientProtocol(false); // Server mode
serverEvent.isProtocolActivation(true); // Activation
// Activate at time 0
VSTask task = new VSTask(0, viz.getProcess(i), serverEvent, false);
taskManager.addTask(task);
System.out.println(" - Server " + i + " will activate at time 0");
}
// Activate Raft CLIENTS on processes 3, 4
// Clients will react to server heartbeats and start sending requests
System.out.println("\nCreating Raft client activations...");
for (int i = 3; i < 5; i++) {
VSProtocolEvent clientEvent = new VSProtocolEvent();
clientEvent.setProtocolClassname(RAFT_PROTOCOL);
clientEvent.isClientProtocol(true); // Client mode
clientEvent.isProtocolActivation(true); // Activation
// Activate clients a bit later so servers have time to elect leader
VSTask task = new VSTask(300 + (i-3)*100, viz.getProcess(i), clientEvent, false);
taskManager.addTask(task);
System.out.println(" - Client " + (i-3) + " will activate at time " + (300 + (i-3)*100));
}
// Add crash/recovery to demonstrate leader re-election
System.out.println("\nAdding failure scenarios...");
// Crash server 0 at time 1000
VSProcessCrashEvent crash = new VSProcessCrashEvent();
VSTask crashTask = new VSTask(1000, viz.getProcess(0), crash, false);
taskManager.addTask(crashTask);
System.out.println(" - Server 0 will crash at time 1000");
// Recover server 0 at time 1500
VSProcessRecoverEvent recover = new VSProcessRecoverEvent();
VSTask recoverTask = new VSTask(1500, viz.getProcess(0), recover, false);
taskManager.addTask(recoverTask);
System.out.println(" - Server 0 will recover at time 1500");
// Save simulation
File outputFile = new File("saved-simulations/raft-simple.dat");
outputFile.getParentFile().mkdirs();
VSSerialize serialize = new VSSerialize();
serialize.saveSimulator(outputFile.getAbsolutePath(), simulator);
frame.dispose();
System.out.println("\n===========================================");
System.out.println("Simple Raft simulation saved successfully!");
System.out.println("===========================================");
System.out.println("\nFile: " + outputFile.getAbsolutePath());
System.out.println("\nWhat happens in this simulation:");
System.out.println("1. Time 0: Three Raft servers start and begin leader election");
System.out.println("2. Time ~150-300: One server becomes leader (watch for election messages)");
System.out.println("3. Time 300: First client activates and starts sending requests");
System.out.println("4. Time 400: Second client activates and starts sending requests");
System.out.println("5. Time 1000: Server 0 crashes, triggering new leader election");
System.out.println("6. Time 1500: Server 0 recovers and rejoins as follower");
System.out.println("\nTo run the simulation:");
System.out.println("1. java -jar target/ds-sim-1.0.1-SNAPSHOT.jar");
System.out.println("2. File -> Open -> saved-simulations/raft-simple.dat");
System.out.println("3. Click 'Run' and watch the Raft consensus in action!");
System.out.println("\nLook for:");
System.out.println("- REQUEST_VOTE and VOTE_RESPONSE messages during elections");
System.out.println("- APPEND_ENTRIES messages (heartbeats) from leader");
System.out.println("- CLIENT_REQUEST messages and their processing");
System.exit(0);
}
}
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