Merge branch 'feat/network-manager' into 'main'

Add (v1) NetworkManager, Session and Transport

See merge request cs108-fs26/Gruppe-13!17

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/ServerApp.java

@@ -1,8 +1,22 @@
 package ch.unibas.dmi.dbis.cs108.casono.server;
 
+import ch.unibas.dmi.dbis.cs108.casono.server.network.NetworkManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.events.DisconnectEvent;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.events.EventBus;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionManager;
+
+/**
+ * Application class for starting the server.
+ */
 public class ServerApp {
     public static void start(String arg) {
         int port = Integer.parseInt(arg);
         System.out.println("You've selected the server. It will accept connections at port " + port);
+
+        EventBus eventBus = new EventBus();
+        SessionManager sessionManager = new SessionManager();
+        eventBus.subscribe(DisconnectEvent.class, event -> sessionManager.removeSession(event.sessionId()));
+        NetworkManager networkManager = new NetworkManager(port, sessionManager, eventBus);
+        networkManager.start();
     }
 }

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/NetworkManager.java

@@ -0,0 +1,81 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.net.Socket;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.events.DisconnectEvent;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.events.EventBus;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.Session;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionManager;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.TcpTransport;
+
+/**
+ * Creates and manages the server socket. Accepts new incoming connections and creates sessions.
+ */
+public class NetworkManager implements Runnable {
+    private Integer port;
+    private Logger logger;
+    private Thread thread;
+    private Boolean running;
+    private SessionManager sessionManager;
+    private EventBus eventBus;
+
+    /**
+     * Creates a new NetworkManager with the given port, session manager, and event bus.
+     *
+     * @param port           the port to listen on
+     * @param sessionManager the session manager to use
+     * @param eventBus       the event bus for events
+     */
+    public NetworkManager(Integer port, SessionManager sessionManager, EventBus eventBus) {
+        this.port = port;
+        this.logger = LogManager.getLogger(NetworkManager.class);
+        this.thread = new Thread(this, "networkManager");
+        this.running = true;
+        this.sessionManager = sessionManager;
+        this.eventBus = eventBus;
+        this.eventBus.subscribe(DisconnectEvent.class, event -> clientDisconnected(event));
+    }
+
+    /**
+     * Starts the internal thread to accept new connections.
+     */
+    public void start() {
+        logger.debug("Starting server at port " + port);
+        thread.start();
+    }
+
+    /**
+     * Handles client disconnection events.
+     *
+     * @param event the disconnect event
+     */
+    public void clientDisconnected(DisconnectEvent event) {
+        logger.info("Session " + event.sessionId().value() + " disconnected adhasghd");
+    }
+
+    /**
+     * Runs the network manager loop, accepting connections.
+     */
+    @Override
+    public void run() {
+        try (ServerSocket serverSocket = new ServerSocket(port)) {
+            while (running) {
+                Socket clientSocket = serverSocket.accept();
+                
+                System.out.println("Accepted connection from " + clientSocket.getRemoteSocketAddress());
+
+                Session session = new Session(new TcpTransport(clientSocket), eventBus);
+                sessionManager.addSession(session);
+                session.start();
+            }
+
+        } catch (IOException e) {
+            logger.fatal(e);
+        }
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/events/DisconnectEvent.java

@@ -0,0 +1,8 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.events;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.sessions.SessionId;
+
+/**
+ * Represents a disconnect event for a session.
+ */
+public record DisconnectEvent(SessionId sessionId) implements Event {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/events/Event.java

@@ -0,0 +1,6 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.events;
+
+/**
+ * Marker interface for events in the event bus system.
+ */
+interface Event {}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/events/EventBus.java

@@ -0,0 +1,40 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.events;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.function.Consumer;
+
+/**
+ * A simple event bus for publishing and subscribing to events.
+ */
+public class EventBus {
+    private final Map<Class<?>, List<Consumer<Object>>> handlers = new ConcurrentHashMap<>();
+
+    /**
+     * Subscribes a handler to a specific event type.
+     *
+     * @param eventType the class of the event to subscribe to
+     * @param handler   the consumer to handle the event
+     */
+    @SuppressWarnings("unchecked") // This cast is safe, because handlers only get passed the type they subscribed to
+    public <T extends Event> void subscribe(Class<T> eventType, Consumer<T> handler) {
+        handlers.computeIfAbsent(eventType, k -> new CopyOnWriteArrayList<>())
+                .add((Consumer<Object>) (Consumer<?>) handler);
+    }
+
+    /**
+     * Publishes an event to all subscribed handlers.
+     *
+     * @param event the event to publish
+     */
+    public <T extends Event> void publish(T event) {
+        Objects.requireNonNull(event, "event must not be null");
+        List<Consumer<Object>> subscribers = handlers.get(event.getClass());
+        if (subscribers != null) {
+            subscribers.forEach(h -> h.accept(event));
+        }
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/sessions/Session.java

@@ -0,0 +1,85 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.sessions;
+
+import java.io.EOFException;
+import java.io.IOException;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+
+import ch.unibas.dmi.dbis.cs108.casono.server.network.events.DisconnectEvent;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.events.EventBus;
+import ch.unibas.dmi.dbis.cs108.casono.server.network.transport.TransportLayer;
+
+/**
+ * Represents a client session in the network server.
+ */
+public class Session implements Runnable {
+    private SessionId id;
+    private Thread thread;
+    private TransportLayer transport;
+    private Logger logger;
+    private Boolean running;
+    private EventBus eventBus;
+    
+    /**
+     * Creates a new Session with the given transport and event bus.
+     *
+     * @param transport the transport layer for communication
+     * @param eventBus  the event bus for publishing events
+     * @throws IOException if an I/O error occurs during initialization
+     */
+    public Session(TransportLayer transport, EventBus eventBus) throws IOException {
+        this.id = new SessionId();
+        this.thread = new Thread(this, "session-" + this.id.value());
+        this.transport = transport;
+        this.running = true;
+        this.eventBus = eventBus;
+
+        this.logger = LogManager.getLogger(Session.class.toString() + id.value());
+        this.logger.info("Created new session");
+    }
+
+    /**
+     * Returns the ID of this session.
+     *
+     * @return the session ID
+     */
+    public SessionId getId() {
+        return this.id;
+    }
+
+    /**
+     * Starts the session thread.
+     */
+    public void start() {
+        thread.start();
+    }
+
+    /**
+     * Closes the session and its transport.
+     *
+     * @throws IOException if an I/O error occurs
+     */
+    public void close() throws IOException {
+        transport.close();
+        this.running = false;
+    }
+
+    /**
+     * Runs the session loop, reading from the transport.
+     */
+    @Override
+    public void run() {
+        while (running) {
+            try {
+                System.out.println("Recieved: " + transport.read());
+            } catch (EOFException e) {
+                logger.info("Client disconnected");
+                eventBus.publish(new DisconnectEvent(id));
+                break;
+            } catch (IOException e) {
+                e.printStackTrace();
+                break;
+            }
+        }
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/sessions/SessionId.java

@@ -0,0 +1,35 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.sessions;
+
+import java.util.UUID;
+
+/**
+ * Represents a unique identifier for a session.
+ */
+public class SessionId {
+    private final UUID value;
+
+    /**
+     * Creates a new SessionId with a randomly generated UUID.
+     */
+    public SessionId() {
+        this.value = UUID.randomUUID();
+    }
+
+    /**
+     * Creates a new SessionId with the specified UUID.
+     *
+     * @param UUID to use for this SessionId
+     */
+    public SessionId(UUID value) {
+        this.value = value;
+    }
+
+    /**
+     * Returns the UUID value of this SessionId.
+     *
+     * @return the UUID value
+     */
+    public UUID value() {
+        return value;
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/sessions/SessionManager.java

@@ -0,0 +1,59 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.sessions;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Manages active sessions in the server.
+ */
+public class SessionManager {
+    private Map<SessionId, Session> sessions;
+
+    /**
+     * Constructs a new SessionManager.
+     */
+    public SessionManager() {
+        this.sessions = new ConcurrentHashMap<>();
+    }
+
+    /**
+     * Adds a session to the manager.
+     *
+     * @param session the session to add
+     */
+    public void addSession(Session session) {
+        sessions.put(session.getId(), session);
+        System.out.println("Added session " + session.getId().value() + " to session manager");
+    }
+
+    /**
+     * Removes a session by its ID.
+     *
+     * @param id the ID of the session to remove
+     * @return the removed session, or null if not found
+     */
+    public Session removeSession(SessionId id) {
+        System.out.println("Removed session " + id.value() + " from session manager");
+        return sessions.remove(id);
+    }
+
+    /**
+     * Removes the specified session.
+     *
+     * @param session the session to remove
+     * @return the removed session, or null if not found
+     */
+    public Session removeSession(Session session) {
+        return sessions.remove(session.getId());
+    }
+
+    /**
+     * Retrieves a session by its ID.
+     *
+     * @param id the ID of the session to retrieve
+     * @return the session with the specified ID, or null if not found
+     */
+    public Session getSessionById(SessionId id) {
+        return sessions.get(id);
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/transport/TcpTransport.java

@@ -0,0 +1,63 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.transport;
+
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * Implements TCP-based transport layer for network communication.
+ */
+public class TcpTransport implements TransportLayer {
+    private Socket socket;
+    private DataInputStream in;
+    private DataOutputStream out;
+
+    /**
+     * Creates a new TcpTransport with the given socket.
+     *
+     * @param socket the socket to use for communication
+     * @throws IOException if an I/O error occurs
+     */
+    public TcpTransport(Socket socket) throws IOException {
+        this.socket = socket;
+        this.in = new DataInputStream(socket.getInputStream());
+        this.out = new DataOutputStream(socket.getOutputStream());
+    }
+
+    /**
+     * Reads a string from the socket.
+     *
+     * @return the read string
+     * @throws IOException if an I/O error occurs
+     */
+    public String read() throws IOException {
+        int length = in.readInt();
+        byte[] payload = new byte[length];
+        in.readFully(payload);
+        return new String(payload, StandardCharsets.UTF_8);
+    }
+
+    /**
+     * Writes a string to the socket.
+     *
+     * @param payload the string to write
+     * @throws IOException if an I/O error occurs
+     */
+    public void write(String payload) throws IOException {
+        byte[] rawPayload = payload.getBytes(StandardCharsets.UTF_8);
+        out.writeInt(rawPayload.length);
+        out.write(rawPayload);
+        out.flush();    
+    }
+
+    /**
+     * Closes the socket.
+     *
+     * @throws IOException if an I/O error occurs
+     */
+    public void close() throws IOException {
+        socket.close();
+    }
+}

src/main/java/ch/unibas/dmi/dbis/cs108/casono/server/network/transport/TransportLayer.java

@@ -0,0 +1,31 @@
+package ch.unibas.dmi.dbis.cs108.casono.server.network.transport;
+
+import java.io.IOException;
+
+/**
+ * Interface for transport layer implementations.
+ */
+public interface TransportLayer {
+    /**
+     * Reads data from the transport layer.
+     *
+     * @return the read data as a string
+     * @throws IOException if an I/O error occurs
+     */
+    String read() throws IOException;
+
+    /**
+     * Writes data to the transport layer.
+     *
+     * @param data the data to write
+     * @throws IOException if an I/O error occurs
+     */
+    void write(String data) throws IOException;
+
+    /**
+     * Closes the transport layer.
+     *
+     * @throws IOException if an I/O error occurs
+     */
+    void close() throws IOException;
+}