Made local database persistence optional

* Split LocalDB into abstract class LocalDb and PersistentLocalDb and
TransientLocalDb
* Moved LocalDb to database package
* Added ignoreLocalDb option to Config

src/main/java/envoy/client/Client.java

@@ -9,6 +9,7 @@ import java.util.logging.Logger;
 
 import javax.naming.TimeLimitExceededException;
 
+import envoy.client.database.LocalDb;
 import envoy.client.net.ReceivedMessageProcessor;
 import envoy.client.net.Receiver;
 import envoy.client.util.EnvoyLog;
@@ -48,13 +49,13 @@ public class Client implements Closeable {
 	 * an exception is thrown.
 	 *
 	 * @param credentials       the login credentials of the user
-	 * @param localDB     the local database used to persist the current
+	 * @param localDb the local database used to persist the current
 	 *                          {@link IdGenerator}
 	 * @throws Exception if the online mode could not be entered or the request
 	 *                   failed for some other reason
 	 * @since Envoy v0.2-alpha
 	 */
-	public void onlineInit(LoginCredentials credentials, LocalDB localDB) throws Exception {
+	public void onlineInit(LoginCredentials credentials, LocalDb localDb) throws Exception {
 		// Establish TCP connection
 		logger.info(String.format("Attempting connection to server %s:%d...", config.getServer(), config.getPort()));
 		socket = new Socket(config.getServer(), config.getPort());
@@ -92,10 +93,10 @@ public class Client implements Closeable {
 		// TODO: Status handling
 
 		// Process message ID generation
-		receiver.registerProcessor(IdGenerator.class, localDB::setIdGenerator);
+		receiver.registerProcessor(IdGenerator.class, localDb::setIdGenerator);
 
 		// Request a generator if none is present
-		if (!localDB.hasIdGenerator() || !localDB.getIdGenerator().hasNext()) requestIdGenerator();
+		if (!localDb.hasIdGenerator() || !localDb.getIdGenerator().hasNext()) requestIdGenerator();
 	}
 
 	/**

src/main/java/envoy/client/Config.java

@@ -1,9 +1,7 @@
 package envoy.client;
 
 import java.io.File;
-import java.util.HashMap;
+import java.util.*;
-import java.util.Map;
-import java.util.Properties;
 import java.util.logging.Level;
 
 import envoy.exception.EnvoyException;
@@ -31,6 +29,7 @@ public class Config {
 		items.put("server", new ConfigItem<>("server", "s", (input) -> input, null));
 		items.put("port", new ConfigItem<>("port", "p", (input) -> Integer.parseInt(input), null));
 		items.put("localDB", new ConfigItem<>("localDB", "db", (input) -> new File(input), new File("localDB")));
+		items.put("ignoreLocalDB", new ConfigItem<>("ignoreLocalDB", "nodb", (input) -> Boolean.parseBoolean(input), false));
 		items.put("homeDirectory",
 				new ConfigItem<>("homeDirectory", "h", (input) -> new File(input), new File(System.getProperty("user.home"), ".envoy")));
 		items.put("fileLevelBarrier", new ConfigItem<>("fileLevelBarrier", "fb", (input) -> Level.parse(input), Level.CONFIG));
@@ -99,7 +98,7 @@ public class Config {
 	 * @return {@code true} if server, port and localDB directory are known.
 	 * @since Envoy v0.1-alpha
 	 */
-	public boolean isInitialized() { return items.values().stream().noneMatch(item -> item.get() == null); }
+	public boolean isInitialized() { return items.values().stream().map(ConfigItem::get).noneMatch(Objects::isNull); }
 
 	/**
 	 * @return the host name of the Envoy server
@@ -119,6 +118,12 @@ public class Config {
 	 */
 	public File getLocalDB() { return (File) items.get("localDB").get(); }
 
+	/**
+	 * @return {@code true} if the local database is to be ignored
+	 * @since Envoy v0.3-alpha
+	 */
+	public Boolean isIgnoreLocalDB() { return (Boolean) items.get("ignoreLocalDB").get(); }
+
 	/**
 	 * @return the directory in which all local files are saves
 	 * @since Envoy v0.2-alpha

src/main/java/envoy/client/LocalDB.java

@@ -1,163 +0,0 @@
-package envoy.client;
-
-import java.io.File;
-import java.io.IOException;
-import java.util.*;
-
-import envoy.data.IdGenerator;
-import envoy.data.User;
-import envoy.util.SerializationUtils;
-
-/**
- * Stored information about the current {@link User} and their {@link Chat}s.
- * For message ID generation a {@link IdGenerator} is stored as well.
- * These object are persisted inside a folder of the local file system.<br>
- * <br>
- * Project: <strong>envoy-client</strong><br>
- * File: <strong>LocalDB.java</strong><br>
- * Created: <strong>27.10.2019</strong><br>
- *
- * @author Kai S. K. Engelbart
- * @author Maximilian K&auml;fer
- * @since Envoy v0.1-alpha
- */
-public class LocalDB {
-
-	private File				localDBDir, localDBFile, usersFile, idGeneratorFile;
-	private User				user;
-	private Map<String, User>	users	= new HashMap<>();
-	private List<Chat>			chats	= new ArrayList<>();
-	private IdGenerator			idGenerator;
-
-	/**
-	 * Constructs an empty local database. To serialize any chats to the file
-	 * system, call {@link LocalDB#initializeDBFile()}.
-	 *
-	 * @param localDBDir the directory in which to store users and chats
-	 * @throws IOException if the LocalDB could not be initialized
-	 * @since Envoy v0.1-alpha
-	 */
-	public LocalDB(File localDBDir) throws IOException {
-		this.localDBDir = localDBDir;
-
-		// Initialize local database directory
-		if (localDBDir.exists() && !localDBDir.isDirectory())
-			throw new IOException(String.format("LocalDBDir '%s' is not a directory!", localDBDir.getAbsolutePath()));
-		usersFile		= new File(localDBDir, "users.db");
-		idGeneratorFile	= new File(localDBDir, "id_generator.db");
-	}
-
-	/**
-	 * Creates a database file for a user-specific list of chats.
-	 *
-	 * @throws NullPointerException if the client user is not yet specified
-	 * @since Envoy v0.1-alpha
-	 */
-	public void initializeDBFile() {
-		if (user == null) throw new NullPointerException("Client user is null");
-		localDBFile = new File(localDBDir, user.getId() + ".db");
-	}
-
-	/**
-	 * Stores all users to the local database. If the client user is specified, the
-	 * chats related to this user are stored as well. The message id generator will
-	 * also be saved if present.
-	 *
-	 * @throws IOException if something went wrong during saving
-	 * @since Envoy v0.1-alpha
-	 */
-	public void save() throws IOException {
-		// Save users
-		SerializationUtils.write(usersFile, users);
-
-		// Save chats
-		if (user != null) SerializationUtils.write(localDBFile, chats);
-
-		// Save id generator
-		if (hasIdGenerator()) SerializationUtils.write(idGeneratorFile, idGenerator);
-	}
-
-	/**
-	 * Loads all users that are stored in the local database.
-	 *
-	 * @throws IOException            if the loading process failed
-	 * @throws ClassNotFoundException if the loading process failed
-	 * @since Envoy v0.2-alpha
-	 */
-	public void loadUsers() throws ClassNotFoundException, IOException { users = SerializationUtils.read(usersFile, HashMap.class); }
-
-	/**
-	 * Loads all chats saved by Envoy for the client user.
-	 *
-	 * @throws IOException            if the loading process failed
-	 * @throws ClassNotFoundException if the loading process failed
-	 * @since Envoy v0.1-alpha
-	 */
-	public void loadChats() throws ClassNotFoundException, IOException { chats = SerializationUtils.read(localDBFile, ArrayList.class); }
-
-	/**
-	 * Loads the message ID generator that is stored in the local database. If the
-	 * file is not found, the exception is ignored.
-	 *
-	 * @since Envoy v0.3-alpha
-	 */
-	public void loadIdGenerator() {
-		try {
-			idGenerator = SerializationUtils.read(idGeneratorFile, IdGenerator.class);
-		} catch (ClassNotFoundException | IOException e) {}
-	}
-
-	/**
-	 * @return a {@code Map<String, User>} of all users stored locally with their
-	 *         user names as keys
-	 * @since Envoy v0.2-alpha
-	 */
-	public Map<String, User> getUsers() { return users; }
-
-	/**
-	 * @param users the users to set
-	 */
-	public void setUsers(Map<String, User> users) { this.users = users; }
-
-	/**
-	 * @return all saved {@link Chat} objects that list the client user as the
-	 *         sender
-	 * @since Envoy v0.1-alpha
-	 **/
-	public List<Chat> getChats() { return chats; }
-
-	/**
-	 * @param chats the chats to set
-	 */
-	public void setChats(List<Chat> chats) { this.chats = chats; }
-
-	/**
-	 * @return the {@link User} who initialized the local database
-	 * @since Envoy v0.2-alpha
-	 */
-	public User getUser() { return user; }
-
-	/**
-	 * @param user the user to set
-	 * @since Envoy v0.2-alpha
-	 */
-	public void setUser(User user) { this.user = user; }
-
-	/**
-	 * @return the message ID generator
-	 * @since Envoy v0.3-alpha
-	 */
-	public IdGenerator getIdGenerator() { return idGenerator; }
-
-	/**
-	 * @param idGenerator the message ID generator to set
-	 * @since Envoy v0.3-alpha
-	 */
-	public void setIdGenerator(IdGenerator idGenerator) { this.idGenerator = idGenerator; }
-
-	/**
-	 * @return {@code true} if an {@link IdGenerator} is present
-	 * @since Envoy v0.3-alpha
-	 */
-	public boolean hasIdGenerator() { return idGenerator != null; }
-}

src/main/java/envoy/client/database/LocalDb.java

@@ -0,0 +1,119 @@
+package envoy.client.database;
+
+import java.util.*;
+
+import envoy.client.Chat;
+import envoy.data.IdGenerator;
+import envoy.data.User;
+
+/**
+ * Stores information about the current {@link User} and their {@link Chat}s.
+ * For message ID generation a {@link IdGenerator} is stored as well.<br>
+ * <br>
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>LocalDb.java</strong><br>
+ * Created: <strong>3 Feb 2020</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.3-alpha
+ */
+public abstract class LocalDb {
+
+	protected User				user;
+	protected Map<String, User>	users	= new HashMap<>();
+	protected List<Chat>		chats	= new ArrayList<>();
+	protected IdGenerator		idGenerator;
+
+	/**
+	 * Initializes a storage space for a user-specific list of chats.
+	 *
+	 * @since Envoy v0.3-alpha
+	 */
+	public void initializeUserStorage() {}
+
+	/**
+	 * Stores all users. If the client user is specified, their chats will be stored
+	 * as well. The message id generator will also be saved if present.
+	 *
+	 * @throws Exception if the saving process failed
+	 * @since Envoy v0.3-alpha
+	 */
+	public void save() throws Exception {}
+
+	/**
+	 * Loads all user data.
+	 *
+	 * @throws Exception if the loading process failed
+	 * @since Envoy v0.3-alpha
+	 */
+	public void loadUsers() throws Exception {}
+
+	/**
+	 * Loads all chat data of the client user.
+	 *
+	 * @throws Exception if the loading process failed
+	 * @since Envoy v0.3-alpha
+	 */
+	public void loadChats() throws Exception {}
+
+	/**
+	 * Loads the ID generator. Any exception thrown during this process is ignored.
+	 *
+	 * @since Envoy v0.3-alpha
+	 */
+	public void loadIdGenerator() {}
+
+	/**
+	 * @return a {@code Map<String, User>} of all users stored locally with their
+	 *         user names as keys
+	 * @since Envoy v0.2-alpha
+	 */
+	public Map<String, User> getUsers() { return users; }
+
+	/**
+	 * @param users the users to set
+	 */
+	public void setUsers(Map<String, User> users) { this.users = users; }
+
+	/**
+	 * @return all saved {@link Chat} objects that list the client user as the
+	 *         sender
+	 * @since Envoy v0.1-alpha
+	 **/
+	public List<Chat> getChats() { return chats; }
+
+	/**
+	 * @param chats the chats to set
+	 */
+	public void setChats(List<Chat> chats) { this.chats = chats; }
+
+	/**
+	 * @return the {@link User} who initialized the local database
+	 * @since Envoy v0.2-alpha
+	 */
+	public User getUser() { return user; }
+
+	/**
+	 * @param user the user to set
+	 * @since Envoy v0.2-alpha
+	 */
+	public void setUser(User user) { this.user = user; }
+
+	/**
+	 * @return the message ID generator
+	 * @since Envoy v0.3-alpha
+	 */
+	public IdGenerator getIdGenerator() { return idGenerator; }
+
+	/**
+	 * @param idGenerator the message ID generator to set
+	 * @since Envoy v0.3-alpha
+	 */
+	public void setIdGenerator(IdGenerator idGenerator) { this.idGenerator = idGenerator; }
+
+	/**
+	 * @return {@code true} if an {@link IdGenerator} is present
+	 * @since Envoy v0.3-alpha
+	 */
+	public boolean hasIdGenerator() { return idGenerator != null; }
+}

src/main/java/envoy/client/database/PersistentLocalDb.java

@@ -0,0 +1,93 @@
+package envoy.client.database;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+
+import envoy.client.ConfigItem;
+import envoy.data.IdGenerator;
+import envoy.util.SerializationUtils;
+
+/**
+ * Implements a {@link LocalDb} in a way that stores all information inside a
+ * folder on the local file system.<br>
+ * <br>
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>PersistentLocalDb.java</strong><br>
+ * Created: <strong>27.10.2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @author Maximilian K&auml;fer
+ * @since Envoy v0.1-alpha
+ */
+public class PersistentLocalDb extends LocalDb {
+
+	private File localDBDir, localDBFile, usersFile, idGeneratorFile;
+
+	/**
+	 * Initializes an empty local database without a directory. All changes made to
+	 * this instance cannot be saved to the file system.<br>
+	 * <br>
+	 * This constructor shall be used in conjunction with the {@code ignoreLocalDB}
+	 * {@link ConfigItem}.
+	 *
+	 * @since Envoy v0.3-alpha
+	 */
+	public PersistentLocalDb() {}
+
+	/**
+	 * Constructs an empty local database. To serialize any chats to the file
+	 * system, call {@link PersistentLocalDb#initializeUserStorage()}.
+	 *
+	 * @param localDBDir the directory in which to store users and chats
+	 * @throws IOException if the PersistentLocalDb could not be initialized
+	 * @since Envoy v0.1-alpha
+	 */
+	public PersistentLocalDb(File localDBDir) throws IOException {
+		this.localDBDir = localDBDir;
+
+		// Initialize local database directory
+		if (localDBDir.exists() && !localDBDir.isDirectory())
+			throw new IOException(String.format("LocalDBDir '%s' is not a directory!", localDBDir.getAbsolutePath()));
+		usersFile		= new File(localDBDir, "users.db");
+		idGeneratorFile	= new File(localDBDir, "id_generator.db");
+	}
+
+	/**
+	 * Creates a database file for a user-specific list of chats.
+	 *
+	 * @throws NullPointerException if the client user is not yet specified
+	 * @since Envoy v0.1-alpha
+	 */
+	@Override
+	public void initializeUserStorage() {
+		if (user == null) throw new NullPointerException("Client user is null");
+		localDBFile = new File(localDBDir, user.getId() + ".db");
+	}
+
+	@Override
+	public void save() throws IOException {
+		// Save users
+		SerializationUtils.write(usersFile, users);
+
+		// Save chats
+		if (user != null) SerializationUtils.write(localDBFile, chats);
+
+		// Save id generator
+		if (hasIdGenerator()) SerializationUtils.write(idGeneratorFile, idGenerator);
+	}
+
+	@Override
+	public void loadUsers() throws ClassNotFoundException, IOException { users = SerializationUtils.read(usersFile, HashMap.class); }
+
+	@Override
+	public void loadChats() throws ClassNotFoundException, IOException { chats = SerializationUtils.read(localDBFile, ArrayList.class); }
+
+	@Override
+	public void loadIdGenerator() {
+		try {
+			idGenerator = SerializationUtils.read(idGeneratorFile, IdGenerator.class);
+		} catch (ClassNotFoundException | IOException e) {}
+	}
+}

src/main/java/envoy/client/database/TransientLocalDb.java

@@ -0,0 +1,15 @@
+package envoy.client.database;
+
+/**
+ * Implements a {@link LocalDb} in a way that does not persist any information
+ * after application shutdown.<br>
+ * <br>
+ * Project: <strong>envoy-client</strong><br>
+ * File: <strong>TransientLocalDb.java</strong><br>
+ * Created: <strong>3 Feb 2020</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.3-alpha
+ */
+public class TransientLocalDb extends LocalDb {
+}

src/main/java/envoy/client/ui/ChatWindow.java

@@ -9,7 +9,10 @@ import java.util.logging.Logger;
 import javax.swing.*;
 import javax.swing.border.EmptyBorder;
 
-import envoy.client.*;
+import envoy.client.Chat;
+import envoy.client.Client;
+import envoy.client.Settings;
+import envoy.client.database.LocalDb;
 import envoy.client.event.MessageCreationEvent;
 import envoy.client.event.ThemeChangeEvent;
 import envoy.client.ui.list.ComponentList;
@@ -34,7 +37,7 @@ public class ChatWindow extends JFrame {
 
 	// User specific objects
 	private Client	client;
-	private LocalDB	localDB;
+	private LocalDb	localDb;
 
 	// GUI components
 	private JPanel					contentPane				= new JPanel();
@@ -161,13 +164,13 @@ public class ChatWindow extends JFrame {
 		userList.setCellRenderer(new UserListRenderer());
 		userList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
 		userList.addListSelectionListener((listSelectionEvent) -> {
-			if (client != null && localDB != null && !listSelectionEvent.getValueIsAdjusting()) {
+			if (client != null && localDb != null && !listSelectionEvent.getValueIsAdjusting()) {
 				@SuppressWarnings("unchecked")
 				final JList<User>	selectedUserList	= (JList<User>) listSelectionEvent.getSource();
 				final User			user				= selectedUserList.getSelectedValue();
 
 				// Select current chat
-				currentChat = localDB.getChats().stream().filter(chat -> chat.getRecipient().getId() == user.getId()).findFirst().get();
+				currentChat = localDb.getChats().stream().filter(chat -> chat.getRecipient().getId() == user.getId()).findFirst().get();
 
 				// Read current Chat
 				currentChat.read();
@@ -206,7 +209,7 @@ public class ChatWindow extends JFrame {
 		// Listen to received messages
 		EventBus.getInstance().register(MessageCreationEvent.class, (evt) -> {
 			Message message = ((MessageCreationEvent) evt).get();
-			localDB.getChats().stream().filter(c -> c.getRecipient().getId() == message.getSenderId()).findFirst().get().appendMessage(message);
+			localDb.getChats().stream().filter(c -> c.getRecipient().getId() == message.getSenderId()).findFirst().get().appendMessage(message);
 			revalidate();
 			repaint();
 		});
@@ -262,7 +265,7 @@ public class ChatWindow extends JFrame {
 		if (!messageEnterTextArea.getText().isEmpty()) try {
 
 			// Create message
-			final Message message = new MessageBuilder(localDB.getUser().getId(), currentChat.getRecipient().getId(), localDB.getIdGenerator())
+			final Message message = new MessageBuilder(localDb.getUser().getId(), currentChat.getRecipient().getId(), localDb.getIdGenerator())
 				.setText(messageEnterTextArea.getText())
 				.build();
 
@@ -270,7 +273,7 @@ public class ChatWindow extends JFrame {
 			// TODO: Store offline messages
 			client.sendMessage(message);
 
-			// Add message to LocalDB and update UI
+			// Add message to PersistentLocalDb and update UI
 			currentChat.appendMessage(message);
 			// messageList.setModel(currentChat.getModel());
 
@@ -281,8 +284,8 @@ public class ChatWindow extends JFrame {
 			revalidate();
 			repaint();
 
-			// Request a new id generator if all ids were used
+			// Request a new id generator if all IDs were used
-			if (!localDB.getIdGenerator().hasNext()) client.requestIdGenerator();
+			if (!localDb.getIdGenerator().hasNext()) client.requestIdGenerator();
 
 		} catch (Exception e) {
 			JOptionPane.showMessageDialog(this,
@@ -302,12 +305,12 @@ public class ChatWindow extends JFrame {
 	private void loadUsersAndChats() {
 		new Thread(() -> {
 			DefaultListModel<User> userListModel = new DefaultListModel<>();
-			localDB.getUsers().values().forEach(user -> {
+			localDb.getUsers().values().forEach(user -> {
 				userListModel.addElement(user);
 
 				// Check if user exists in local DB
-				if (localDB.getChats().stream().filter(c -> c.getRecipient().getId() == user.getId()).count() == 0)
+				if (localDb.getChats().stream().filter(c -> c.getRecipient().getId() == user.getId()).count() == 0)
-					localDB.getChats().add(new Chat(user));
+					localDb.getChats().add(new Chat(user));
 			});
 			SwingUtilities.invokeLater(() -> userList.setModel(userListModel));
 		}).start();
@@ -324,14 +327,16 @@ public class ChatWindow extends JFrame {
 	}
 
 	/**
-	 * Sets the {@link LocalDB} used by this {@link ChatWindow}. After invoking this
+	 * Sets the {@link LocalDb} used by this {@link ChatWindow}. After
+	 * invoking this
 	 * method, users and chats will be loaded from the database into the GUI.
 	 *
-	 * @param localDB the {@link LocalDB} used to manage stored messages and users
+	 * @param localDb the {@link LocalDb} used to manage stored messages
+	 *                and users
 	 * @since Envoy v0.2-alpha
 	 */
-	public void setLocalDB(LocalDB localDB) {
+	public void setLocalDB(LocalDb localDb) {
-		this.localDB = localDB;
+		this.localDb = localDb;
 		loadUsersAndChats();
 	}
 }

src/main/java/envoy/client/ui/Startup.java

@@ -11,7 +11,12 @@ import javax.swing.JFrame;
 import javax.swing.JOptionPane;
 import javax.swing.SwingUtilities;
 
-import envoy.client.*;
+import envoy.client.Client;
+import envoy.client.Config;
+import envoy.client.Settings;
+import envoy.client.database.LocalDb;
+import envoy.client.database.PersistentLocalDb;
+import envoy.client.database.TransientLocalDb;
 import envoy.client.util.EnvoyLog;
 import envoy.data.LoginCredentials;
 import envoy.data.User;
@@ -63,8 +68,8 @@ public class Startup {
 		} catch (Exception e) {
 			JOptionPane
 				.showMessageDialog(null, "Error loading configuration values:\n" + e.toString(), "Configuration error", JOptionPane.ERROR_MESSAGE);
-			System.exit(1);
 			e.printStackTrace();
+			System.exit(1);
 		}
 
 		// Set new logger levels loaded from config
@@ -80,12 +85,19 @@ public class Startup {
 		}
 
 		// Initialize the local database
-		LocalDB localDB;
+		LocalDb localDb;
-		try {
+		if (config.isIgnoreLocalDB()) {
-			localDB = new LocalDB(new File(config.getHomeDirectory(), config.getLocalDB().getPath()));
+			localDb = new TransientLocalDb();
+			JOptionPane.showMessageDialog(null,
+					"Ignoring local database.\nMessages will not be saved!",
+					"Local database warning",
+					JOptionPane.WARNING_MESSAGE);
+		} else try {
+			localDb = new PersistentLocalDb(new File(config.getHomeDirectory(), config.getLocalDB().getPath()));
 		} catch (IOException e3) {
 			logger.log(Level.SEVERE, "Could not initialize local database", e3);
-			JOptionPane.showMessageDialog(null, "Could not initialize local database!\n" + e3.toString());
+			JOptionPane
+				.showMessageDialog(null, "Could not initialize local database!\n" + e3.toString(), "Local database error", JOptionPane.ERROR_MESSAGE);
 			System.exit(1);
 			return;
 		}
@@ -97,15 +109,15 @@ public class Startup {
 		Client client = new Client();
 		try {
 			// Try entering online mode first
-			localDB.loadIdGenerator();
+			localDb.loadIdGenerator();
-			client.onlineInit(credentials, localDB);
+			client.onlineInit(credentials, localDb);
 		} catch (Exception e1) {
 			logger.warning("Could not connect to server. Trying offline mode...");
 			e1.printStackTrace();
 			try {
 				// Try entering offline mode
-				localDB.loadUsers();
+				localDb.loadUsers();
-				User clientUser = localDB.getUsers().get(credentials.getName());
+				User clientUser = localDb.getUsers().get(credentials.getName());
 				if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
 				client.setSender(clientUser);
 				JOptionPane.showMessageDialog(null,
@@ -120,12 +132,12 @@ public class Startup {
 		}
 
 		// Set client user in local database
-		localDB.setUser(client.getSender());
+		localDb.setUser(client.getSender());
 
 		// Initialize chats in local database
 		try {
-			localDB.initializeDBFile();
+			localDb.initializeUserStorage();
-			localDB.loadChats();
+			localDb.loadChats();
 		} catch (FileNotFoundException e) {
 			// The local database file has not yet been created, probably first login
 		} catch (Exception e) {
@@ -137,12 +149,12 @@ public class Startup {
 		}
 
 		// Save all users to the local database
-		if (client.isOnline()) localDB.setUsers(client.getUsers());
+		if (client.isOnline()) localDb.setUsers(client.getUsers());
 
 		EventQueue.invokeLater(() -> {
 			try {
 				chatWindow.setClient(client);
-				chatWindow.setLocalDB(localDB);
+				chatWindow.setLocalDB(localDb);
 
 				try {
 					new StatusTrayIcon(chatWindow).show();
@@ -162,16 +174,16 @@ public class Startup {
 			}
 		});
 
-		// Save Settings and LocalDB on shutdown
+		// Save Settings and PersistentLocalDb on shutdown
 		Runtime.getRuntime().addShutdownHook(new Thread(() -> {
 			try {
 				logger.info("Closing connection...");
 				client.close();
 
 				logger.info("Saving local database and settings...");
-				localDB.save();
+				localDb.save();
 				Settings.getInstance().save();
-			} catch (IOException e) {
+			} catch (Exception e) {
 				logger.log(Level.SEVERE, "Unable to save local files", e);
 			}
 		}));