added dashboard server and built an example implementation for the message protocol

main/src/main/java/sd/dashboard/DashboardClientHandler.java

@@ -0,0 +1,110 @@
+package sd.dashboard;
+
+import java.io.IOException;
+import java.net.Socket;
+
+import sd.model.MessageType;
+import sd.protocol.MessageProtocol;
+import sd.protocol.SocketConnection;
+
+/**
+ * Processes statistics messages from a single client connection.
+ * Runs in a separate thread per client.
+ */
+public class DashboardClientHandler implements Runnable {
+    
+    private final Socket clientSocket;
+    private final DashboardStatistics statistics;
+    
+    public DashboardClientHandler(Socket clientSocket, DashboardStatistics statistics) {
+        this.clientSocket = clientSocket;
+        this.statistics = statistics;
+    }
+    
+    @Override
+    public void run() {
+        String clientInfo = clientSocket.getInetAddress().getHostAddress() + ":" + clientSocket.getPort();
+        
+        try (SocketConnection connection = new SocketConnection(clientSocket)) {
+            System.out.println("[Handler] Started handling client: " + clientInfo);
+            
+            while (!Thread.currentThread().isInterrupted()) {
+                try {
+                    MessageProtocol message = connection.receiveMessage();
+                    
+                    if (message == null) {
+                        System.out.println("[Handler] Client disconnected: " + clientInfo);
+                        break;
+                    }
+                    
+                    processMessage(message);
+                    
+                } catch (ClassNotFoundException e) {
+                    System.err.println("[Handler] Unknown message class from " + clientInfo + ": " + e.getMessage());
+                } catch (IOException e) {
+                    System.out.println("[Handler] Connection error with " + clientInfo + ": " + e.getMessage());
+                    break;
+                }
+            }
+            
+        } catch (IOException e) {
+            System.err.println("[Handler] Error initializing connection with " + clientInfo + ": " + e.getMessage());
+        } finally {
+            try {
+                if (!clientSocket.isClosed()) {
+                    clientSocket.close();
+                }
+            } catch (IOException e) {
+                System.err.println("[Handler] Error closing socket for " + clientInfo + ": " + e.getMessage());
+            }
+        }
+    }
+    
+    private void processMessage(MessageProtocol message) {
+        if (message.getType() != MessageType.STATS_UPDATE) {
+            System.out.println("[Handler] Ignoring non-statistics message type: " + message.getType());
+            return;
+        }
+        
+        String senderId = message.getSourceNode();
+        Object payload = message.getPayload();
+        
+        System.out.println("[Handler] Received STATS_UPDATE from: " + senderId);
+        
+        if (payload instanceof StatsUpdatePayload stats) {
+            updateStatistics(senderId, stats);
+        } else {
+            System.err.println("[Handler] Unknown payload type: " + 
+                (payload != null ? payload.getClass().getName() : "null"));
+        }
+    }
+    
+    private void updateStatistics(String senderId, StatsUpdatePayload stats) {
+        if (stats.getTotalVehiclesGenerated() >= 0) {
+            statistics.updateVehiclesGenerated(stats.getTotalVehiclesGenerated());
+        }
+        
+        if (stats.getTotalVehiclesCompleted() >= 0) {
+            statistics.updateVehiclesCompleted(stats.getTotalVehiclesCompleted());
+        }
+        
+        if (stats.getTotalSystemTime() >= 0) {
+            statistics.addSystemTime(stats.getTotalSystemTime());
+        }
+        
+        if (stats.getTotalWaitingTime() >= 0) {
+            statistics.addWaitingTime(stats.getTotalWaitingTime());
+        }
+        
+        if (senderId.startsWith("Cr") || senderId.startsWith("E")) {
+            statistics.updateIntersectionStats(
+                senderId,
+                stats.getIntersectionArrivals(),
+                stats.getIntersectionDepartures(),
+                stats.getIntersectionQueueSize()
+            );
+        }
+        
+        System.out.println("[Handler] Successfully updated statistics from: " + senderId);
+    }
+}