Define message types

main/src/main/java/sd/model/Message.java

@@ -0,0 +1,142 @@
+package sd.model;
+
+import java.io.Serializable;
+import java.util.UUID;
+
+/**
+ * Represents a message exchanged between processes in the distributed simulation.
+ * Each message has a unique ID, a type, a sender, a destination, and a payload.
+ * This class implements {@link Serializable} to allow transmission over the network.
+ */
+public class Message implements Serializable {
+    
+    private static final long serialVersionUID = 1L;
+    
+    /**
+     * Unique identifier for this message.
+     */
+    private final String messageId;
+    
+    /**
+     * The type of this message (e.g., VEHICLE_TRANSFER, STATS_UPDATE).
+     */
+    private final MessageType type;
+    
+    /**
+     * Identifier of the process that sent this message.
+     */
+    private final String senderId;
+    
+    /**
+     * Identifier of the destination process. Can be null for broadcast messages.
+     */
+    private final String destinationId;
+    
+    /**
+     * The actual data being transmitted. Type depends on the message type.
+     */
+    private final Object payload;
+    
+    /**
+     * Timestamp when this message was created (simulation time or real time).
+     */
+    private final long timestamp;
+    
+    /**
+     * Creates a new message with all parameters.
+     *
+     * @param type The message type
+     * @param senderId The ID of the sending process
+     * @param destinationId The ID of the destination process (null for broadcast)
+     * @param payload The message payload
+     * @param timestamp The timestamp of message creation
+     */
+    public Message(MessageType type, String senderId, String destinationId, 
+                   Object payload, long timestamp) {
+        this.messageId = UUID.randomUUID().toString();
+        this.type = type;
+        this.senderId = senderId;
+        this.destinationId = destinationId;
+        this.payload = payload;
+        this.timestamp = timestamp;
+    }
+    
+    /**
+     * Creates a new message with current system time as timestamp.
+     *
+     * @param type The message type
+     * @param senderId The ID of the sending process
+     * @param destinationId The ID of the destination process
+     * @param payload The message payload
+     */
+    public Message(MessageType type, String senderId, String destinationId, Object payload) {
+        this(type, senderId, destinationId, payload, System.currentTimeMillis());
+    }
+    
+    /**
+     * Creates a broadcast message (no specific destination).
+     *
+     * @param type The message type
+     * @param senderId The ID of the sending process
+     * @param payload The message payload
+     */
+    public Message(MessageType type, String senderId, Object payload) {
+        this(type, senderId, null, payload, System.currentTimeMillis());
+    }
+    
+    //Getters
+    
+    public String getMessageId() {
+        return messageId;
+    }
+    
+    public MessageType getType() {
+        return type;
+    }
+    
+    public String getSenderId() {
+        return senderId;
+    }
+    
+    public String getDestinationId() {
+        return destinationId;
+    }
+    
+    public Object getPayload() {
+        return payload;
+    }
+    
+    public long getTimestamp() {
+        return timestamp;
+    }
+    
+    /**
+     * Checks if this is a broadcast message (no specific destination).
+     *
+     * @return true if destinationId is null, false otherwise
+     */
+    public boolean isBroadcast() {
+        return destinationId == null;
+    }
+    
+    /**
+     * Gets the payload cast to a specific type.
+     * Use with caution and ensure type safety.
+     *
+     * @param <T> The expected payload type
+     * @return The payload cast to type T
+     * @throws ClassCastException if the payload is not of type T
+     */
+    @SuppressWarnings("unchecked")
+    public <T> T getPayloadAs(Class<T> clazz) {
+        return (T) payload;
+    }
+    
+    @Override
+    public String toString() {
+        return String.format("Message[id=%s, type=%s, from=%s, to=%s, timestamp=%d]",
+                           messageId, type, senderId, 
+                           destinationId != null ? destinationId : "BROADCAST",
+                           timestamp);
+    }
+}

main/src/main/java/sd/model/MessageType.java

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+package sd.model;
+
+/**
+ * Enumeration representing all possible message types for distributed communication.
+ * These types are used for inter-process communication between different components
+ * of the distributed traffic simulation system.
+ */
+public enum MessageType {
+    
+    /**
+     * Message to transfer a vehicle between intersections or processes.
+     * Payload: Vehicle object with current state
+     */
+    VEHICLE_TRANSFER,
+    
+    /**
+     * Message to update statistics across the distributed system.
+     * Payload: Statistics data (waiting times, queue sizes, etc.)
+     */
+    STATS_UPDATE,
+    
+    /**
+     * Message to synchronize traffic light states between processes.
+     * Payload: TrafficLight state and timing information
+     */
+    TRAFFIC_LIGHT_SYNC,
+    
+    /**
+     * Heartbeat message to check if a process is alive.
+     * Payload: Process ID and timestamp
+     */
+    HEARTBEAT,
+    
+    /**
+     * Request to join the distributed simulation.
+     * Payload: Process information and capabilities
+     */
+    JOIN_REQUEST,
+    
+    /**
+     * Response to a join request.
+     * Payload: Acceptance status and configuration
+     */
+    JOIN_RESPONSE,
+    
+    /**
+     * Message to notify about a new vehicle generation.
+     * Payload: Vehicle generation parameters
+     */
+    VEHICLE_SPAWN,
+    
+    /**
+     * Message to request the current state of an intersection.
+     * Payload: Intersection ID
+     */
+    STATE_REQUEST,
+    
+    /**
+     * Response containing the current state of an intersection.
+     * Payload: Complete intersection state
+     */
+    STATE_RESPONSE,
+    
+    /**
+     * Message to signal shutdown of a process.
+     * Payload: Process ID and reason
+     */
+    SHUTDOWN,
+    
+    /**
+     * Acknowledgment message for reliable communication.
+     * Payload: Message ID being acknowledged
+     */
+    ACK,
+    
+    /**
+     * Error message to report problems in the distributed system.
+     * Payload: Error description and context
+     */
+    ERROR
+}