Merge pull request #5 from andrewlalis/messageRefactor

Refactored core message structure to use records.

client/src/main/java/nl/andrewl/concord_client/ConcordClient.java

@@ -20,6 +20,12 @@ import nl.andrewl.concord_core.msg.Encryption;
 import nl.andrewl.concord_core.msg.Message;
 import nl.andrewl.concord_core.msg.Serializer;
 import nl.andrewl.concord_core.msg.types.*;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryRequest;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryResponse;
+import nl.andrewl.concord_core.msg.types.client_setup.Identification;
+import nl.andrewl.concord_core.msg.types.client_setup.ServerWelcome;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -84,8 +90,8 @@ public class ConcordClient implements Runnable {
 		this.serializer.writeMessage(new Identification(nickname, token), this.out);
 		Message reply = this.serializer.readMessage(this.in);
 		if (reply instanceof ServerWelcome welcome) {
-			var model = new ClientModel(welcome.getClientId(), nickname, welcome.getCurrentChannelId(), welcome.getCurrentChannelName(), welcome.getMetaData());
+			var model = new ClientModel(welcome.clientId(), nickname, welcome.currentChannelId(), welcome.currentChannelName(), welcome.metaData());
-			this.saveSessionToken(welcome.getSessionToken(), tokensFile);
+			this.saveSessionToken(welcome.sessionToken(), tokensFile);
 			// Start fetching initial data for the channel we were initially put into.
 			this.sendMessage(new ChatHistoryRequest(model.getCurrentChannelId(), ""));
 			return model;

client/src/main/java/nl/andrewl/concord_client/event/ChatHistoryListener.java

@@ -1,7 +1,7 @@
 package nl.andrewl.concord_client.event;
 
 import nl.andrewl.concord_client.model.ChatHistory;
-import nl.andrewl.concord_core.msg.types.Chat;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
 
 public interface ChatHistoryListener {
 	default void chatAdded(Chat chat) {}

client/src/main/java/nl/andrewl/concord_client/event/handlers/ChannelMovedHandler.java

@@ -2,10 +2,8 @@ package nl.andrewl.concord_client.event.handlers;
 
 import nl.andrewl.concord_client.ConcordClient;
 import nl.andrewl.concord_client.event.MessageHandler;
-import nl.andrewl.concord_core.msg.types.ChatHistoryRequest;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
-import nl.andrewl.concord_core.msg.types.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryRequest;
-
-import java.util.Map;
 
 /**
  * When the client receives a {@link MoveToChannel} message, it means that the
@@ -16,7 +14,7 @@ import java.util.Map;
 public class ChannelMovedHandler implements MessageHandler<MoveToChannel> {
 	@Override
 	public void handle(MoveToChannel msg, ConcordClient client) throws Exception {
-		client.getModel().setCurrentChannel(msg.getId(), msg.getChannelName());
+		client.getModel().setCurrentChannel(msg.id(), msg.channelName());
-		client.sendMessage(new ChatHistoryRequest(msg.getId()));
+		client.sendMessage(new ChatHistoryRequest(msg.id()));
 	}
 }

client/src/main/java/nl/andrewl/concord_client/event/handlers/ChatHistoryResponseHandler.java

@@ -2,11 +2,14 @@ package nl.andrewl.concord_client.event.handlers;
 
 import nl.andrewl.concord_client.ConcordClient;
 import nl.andrewl.concord_client.event.MessageHandler;
-import nl.andrewl.concord_core.msg.types.ChatHistoryResponse;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryResponse;
+
+import java.util.Arrays;
+import java.util.List;
 
 public class ChatHistoryResponseHandler implements MessageHandler<ChatHistoryResponse> {
 	@Override
 	public void handle(ChatHistoryResponse msg, ConcordClient client) {
-		client.getModel().getChatHistory().setChats(msg.getMessages());
+		client.getModel().getChatHistory().setChats(Arrays.asList(msg.messages()));
 	}
 }

client/src/main/java/nl/andrewl/concord_client/event/handlers/ServerUsersHandler.java

@@ -4,9 +4,11 @@ import nl.andrewl.concord_client.ConcordClient;
 import nl.andrewl.concord_client.event.MessageHandler;
 import nl.andrewl.concord_core.msg.types.ServerUsers;
 
+import java.util.Arrays;
+
 public class ServerUsersHandler implements MessageHandler<ServerUsers> {
 	@Override
 	public void handle(ServerUsers msg, ConcordClient client) {
-		client.getModel().setKnownUsers(msg.getUsers());
+		client.getModel().setKnownUsers(Arrays.asList(msg.users()));
 	}
 }

client/src/main/java/nl/andrewl/concord_client/gui/ChannelList.java

@@ -5,7 +5,7 @@ import com.googlecode.lanterna.gui2.Direction;
 import com.googlecode.lanterna.gui2.LinearLayout;
 import com.googlecode.lanterna.gui2.Panel;
 import nl.andrewl.concord_client.ConcordClient;
-import nl.andrewl.concord_core.msg.types.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
 
 import java.io.IOException;
 
@@ -22,15 +22,15 @@ public class ChannelList extends Panel {
 
 	public void setChannels() {
 		this.removeAllComponents();
-		for (var channel : this.client.getModel().getServerMetaData().getChannels()) {
+		for (var channel : this.client.getModel().getServerMetaData().channels()) {
-			String name = channel.getName();
+			String name = channel.name();
-			if (client.getModel().getCurrentChannelId().equals(channel.getId())) {
+			if (client.getModel().getCurrentChannelId().equals(channel.id())) {
 				name = "*" + name;
 			}
 			Button b = new Button(name, () -> {
-				if (!client.getModel().getCurrentChannelId().equals(channel.getId())) {
+				if (!client.getModel().getCurrentChannelId().equals(channel.id())) {
 					try {
-						client.sendMessage(new MoveToChannel(channel.getId()));
+						client.sendMessage(new MoveToChannel(channel.id()));
 					} catch (IOException e) {
 						e.printStackTrace();
 					}

client/src/main/java/nl/andrewl/concord_client/gui/ChatList.java

@@ -3,7 +3,7 @@ package nl.andrewl.concord_client.gui;
 import com.googlecode.lanterna.gui2.AbstractListBox;
 import nl.andrewl.concord_client.event.ChatHistoryListener;
 import nl.andrewl.concord_client.model.ChatHistory;
-import nl.andrewl.concord_core.msg.types.Chat;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
 
 /**
  * This chat list shows a section of chat messages that have been sent in a

client/src/main/java/nl/andrewl/concord_client/gui/ChatRenderer.java

@@ -4,7 +4,7 @@ import com.googlecode.lanterna.TerminalTextUtils;
 import com.googlecode.lanterna.graphics.ThemeDefinition;
 import com.googlecode.lanterna.gui2.AbstractListBox;
 import com.googlecode.lanterna.gui2.TextGUIGraphics;
-import nl.andrewl.concord_core.msg.types.Chat;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
 
 import java.time.Instant;
 import java.time.ZoneId;
@@ -20,10 +20,10 @@ public class ChatRenderer extends AbstractListBox.ListItemRenderer<Chat, ChatLis
 		else {
 			graphics.applyThemeStyle(themeDefinition.getNormal());
 		}
-		graphics.putString(0, 0, chat.getSenderNickname());
+		graphics.putString(0, 0, chat.senderNickname());
-		Instant timestamp = Instant.ofEpochMilli(chat.getTimestamp());
+		Instant timestamp = Instant.ofEpochMilli(chat.timestamp());
 		String timeStr = timestamp.atZone(ZoneId.systemDefault()).format(DateTimeFormatter.ofPattern("HH:mm"));
-		String label = chat.getSenderNickname() + "@" + timeStr + " : " + chat.getMessage();
+		String label = chat.senderNickname() + "@" + timeStr + " : " + chat.message();
 		label = TerminalTextUtils.fitString(label, graphics.getSize().getColumns());
 		while(TerminalTextUtils.getColumnWidth(label) < graphics.getSize().getColumns()) {
 			label += " ";

client/src/main/java/nl/andrewl/concord_client/gui/UserList.java

@@ -5,7 +5,7 @@ import com.googlecode.lanterna.gui2.Direction;
 import com.googlecode.lanterna.gui2.LinearLayout;
 import com.googlecode.lanterna.gui2.Panel;
 import nl.andrewl.concord_client.ConcordClient;
-import nl.andrewl.concord_core.msg.types.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
 import nl.andrewl.concord_core.msg.types.UserData;
 
 import java.io.IOException;
@@ -22,11 +22,11 @@ public class UserList extends Panel {
 	public void updateUsers(List<UserData> usersResponse) {
 		this.removeAllComponents();
 		for (var user : usersResponse) {
-			Button b = new Button(user.getName(), () -> {
+			Button b = new Button(user.name(), () -> {
-				if (!client.getModel().getId().equals(user.getId())) {
+				if (!client.getModel().getId().equals(user.id())) {
-					System.out.println("Opening DM channel with user " + user.getName() + ", id: " + user.getId());
+					System.out.println("Opening DM channel with user " + user.name() + ", id: " + user.id());
 					try {
-						client.sendMessage(new MoveToChannel(user.getId()));
+						client.sendMessage(new MoveToChannel(user.id()));
 					} catch (IOException e) {
 						e.printStackTrace();
 					}

client/src/main/java/nl/andrewl/concord_client/model/ChatHistory.java

@@ -2,7 +2,7 @@ package nl.andrewl.concord_client.model;
 
 import lombok.Getter;
 import nl.andrewl.concord_client.event.ChatHistoryListener;
-import nl.andrewl.concord_core.msg.types.Chat;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
 
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;

core/src/main/java/module-info.java

@@ -3,5 +3,9 @@ module concord_core {
 
 	exports nl.andrewl.concord_core.util to concord_server, concord_client;
 	exports nl.andrewl.concord_core.msg to concord_server, concord_client;
+
 	exports nl.andrewl.concord_core.msg.types to concord_server, concord_client;
+	exports nl.andrewl.concord_core.msg.types.client_setup to concord_client, concord_server;
+	exports nl.andrewl.concord_core.msg.types.chat to concord_client, concord_server;
+	exports nl.andrewl.concord_core.msg.types.channel to concord_client, concord_server;
 }

core/src/main/java/nl/andrewl/concord_core/msg/Encryption.java

@@ -1,6 +1,6 @@
 package nl.andrewl.concord_core.msg;
 
-import nl.andrewl.concord_core.msg.types.KeyData;
+import nl.andrewl.concord_core.msg.types.client_setup.KeyData;
 import nl.andrewl.concord_core.util.Pair;
 
 import javax.crypto.Cipher;
@@ -64,20 +64,20 @@ public class Encryption {
 		// Receive and decode client's unencrypted key data.
 		KeyData clientKeyData = (KeyData) serializer.readMessage(in);
 		PublicKey clientPublicKey = KeyFactory.getInstance("EC")
-				.generatePublic(new X509EncodedKeySpec(clientKeyData.getPublicKey()));
+				.generatePublic(new X509EncodedKeySpec(clientKeyData.publicKey()));
 
 		// Compute secret key from client's public key and our private key.
 		KeyAgreement ka = KeyAgreement.getInstance("ECDH");
 		ka.init(keyPair.getPrivate());
 		ka.doPhase(clientPublicKey, true);
-		byte[] secretKey = computeSecretKey(ka.generateSecret(), publicKey, clientKeyData.getPublicKey());
+		byte[] secretKey = computeSecretKey(ka.generateSecret(), publicKey, clientKeyData.publicKey());
 
 		// Initialize cipher streams.
 		Cipher writeCipher = Cipher.getInstance("AES/CFB8/NoPadding");
 		Cipher readCipher = Cipher.getInstance("AES/CFB8/NoPadding");
 		Key cipherKey = new SecretKeySpec(secretKey, "AES");
 		writeCipher.init(Cipher.ENCRYPT_MODE, cipherKey, new IvParameterSpec(iv));
-		readCipher.init(Cipher.DECRYPT_MODE, cipherKey, new IvParameterSpec(clientKeyData.getIv()));
+		readCipher.init(Cipher.DECRYPT_MODE, cipherKey, new IvParameterSpec(clientKeyData.iv()));
 		return new Pair<>(
 				new CipherInputStream(in, readCipher),
 				new CipherOutputStream(out, writeCipher)

core/src/main/java/nl/andrewl/concord_core/msg/Message.java

@@ -1,11 +1,5 @@
 package nl.andrewl.concord_core.msg;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.nio.charset.StandardCharsets;
-import java.util.UUID;
-
 /**
  * Represents any message which can be sent over the network.
  * <p>
@@ -14,26 +8,12 @@ import java.util.UUID;
  * </p>
  */
 public interface Message {
-	/**
+	@SuppressWarnings("unchecked")
-	 * @return The exact number of bytes that this message will use when written
+	default <T extends Message> MessageType<T> getType() {
-	 * to a stream.
+		return MessageType.get((Class<T>) this.getClass());
-	 */
+	}
-	int getByteCount();
+
-
+	default int byteSize() {
-	/**
+		return getType().byteSizeFunction().apply(this);
-	 * Writes this message to the given output stream.
+	}
-	 * @param o The output stream to write to.
-	 * @throws IOException If an error occurs while writing.
-	 */
-	void write(DataOutputStream o) throws IOException;
-
-	/**
-	 * Reads all of this message's properties from the given input stream.
-	 * <p>
-	 *     The single byte type identifier has already been read.
-	 * </p>
-	 * @param i The input stream to read from.
-	 * @throws IOException If an error occurs while reading.
-	 */
-	void read(DataInputStream i) throws IOException;
 }

core/src/main/java/nl/andrewl/concord_core/msg/MessageReader.java

@@ -0,0 +1,19 @@
+package nl.andrewl.concord_core.msg;
+
+import nl.andrewl.concord_core.util.ExtendedDataInputStream;
+
+import java.io.IOException;
+
+@FunctionalInterface
+public interface MessageReader<T extends Message>{
+	/**
+	 * Reads all of this message's properties from the given input stream.
+	 * <p>
+	 *     The single byte type identifier has already been read.
+	 * </p>
+	 * @param in The input stream to read from.
+	 * @return The message that was read.
+	 * @throws IOException If an error occurs while reading.
+	 */
+	T read(ExtendedDataInputStream in) throws IOException;
+}

core/src/main/java/nl/andrewl/concord_core/msg/MessageType.java

@@ -0,0 +1,130 @@
+package nl.andrewl.concord_core.msg;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.RecordComponent;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.function.Function;
+
+/**
+ * Record containing the components needed to read and write a given message.
+ * <p>
+ *     Also contains methods for automatically generating message type
+ *     implementations for standard record-based messages.
+ * </p>
+ * @param <T> The type of message.
+ * @param messageClass The class of the message.
+ * @param byteSizeFunction A function that computes the byte size of the message.
+ * @param reader A reader that can read messages from an input stream.
+ * @param writer A writer that write messages from an input stream.
+ */
+public record MessageType<T extends Message>(
+		Class<T> messageClass,
+		Function<T, Integer> byteSizeFunction,
+		MessageReader<T> reader,
+		MessageWriter<T> writer
+) {
+	private static final Map<Class<?>, MessageType<?>> generatedMessageTypes = new HashMap<>();
+
+	/**
+	 * Gets the {@link MessageType} instance for a given message class, and
+	 * generates a new implementation if none exists yet.
+	 * @param messageClass The class of the message to get a type for.
+	 * @param <T> The type of the message.
+	 * @return The message type.
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T extends Message> MessageType<T> get(Class<T> messageClass) {
+		return (MessageType<T>) generatedMessageTypes.computeIfAbsent(messageClass, c -> generateForRecord((Class<T>) c));
+	}
+
+	/**
+	 * Generates a message type instance for a given class, using reflection to
+	 * introspect the fields of the message.
+	 * <p>
+	 *     Note that this only works for record-based messages.
+	 * </p>
+	 * @param messageTypeClass The class of the message type.
+	 * @param <T> The type of the message.
+	 * @return A message type instance.
+	 */
+	public static <T extends Message> MessageType<T> generateForRecord(Class<T> messageTypeClass) {
+		RecordComponent[] components = messageTypeClass.getRecordComponents();
+		Constructor<T> constructor;
+		try {
+			constructor = messageTypeClass.getDeclaredConstructor(Arrays.stream(components)
+					.map(RecordComponent::getType).toArray(Class<?>[]::new));
+		} catch (NoSuchMethodException e) {
+			throw new IllegalArgumentException(e);
+		}
+		return new MessageType<>(
+				messageTypeClass,
+				generateByteSizeFunction(components),
+				generateReader(constructor),
+				generateWriter(components)
+		);
+	}
+
+	/**
+	 * Generates a function implementation that counts the byte size of a
+	 * message based on the message's record component types.
+	 * @param components The list of components that make up the message.
+	 * @param <T> The message type.
+	 * @return A function that computes the byte size of a message of the given
+	 * type.
+	 */
+	private static <T extends Message> Function<T, Integer> generateByteSizeFunction(RecordComponent[] components) {
+		return msg -> {
+			int size = 0;
+			for (var component : components) {
+				try {
+					size += MessageUtils.getByteSize(component.getAccessor().invoke(msg));
+				} catch (ReflectiveOperationException e) {
+					throw new IllegalStateException(e);
+				}
+			}
+			return size;
+		};
+	}
+
+	/**
+	 * Generates a message reader for the given message constructor method. It
+	 * will try to read objects from the input stream according to the
+	 * parameters of the canonical constructor of a message record.
+	 * @param constructor The canonical constructor of the message record.
+	 * @param <T> The message type.
+	 * @return A message reader for the given type.
+	 */
+	private static <T extends Message> MessageReader<T> generateReader(Constructor<T> constructor) {
+		return in -> {
+			Object[] values = new Object[constructor.getParameterCount()];
+			for (int i = 0; i < values.length; i++) {
+				values[i] = in.readObject(constructor.getParameterTypes()[i]);
+			}
+			try {
+				return constructor.newInstance(values);
+			} catch (ReflectiveOperationException e) {
+				throw new IllegalStateException(e);
+			}
+		};
+	}
+
+	/**
+	 * Generates a message writer for the given message record components.
+	 * @param components The record components to write.
+	 * @param <T> The type of message.
+	 * @return The message writer for the given type.
+	 */
+	private static <T extends Message> MessageWriter<T> generateWriter(RecordComponent[] components) {
+		return (msg, out) -> {
+			for (var component: components) {
+				try {
+					out.writeObject(component.getAccessor().invoke(msg), component.getType());
+				} catch (ReflectiveOperationException e) {
+					throw new IllegalStateException(e);
+				}
+			}
+		};
+	}
+}

core/src/main/java/nl/andrewl/concord_core/msg/MessageUtils.java

@@ -1,11 +1,6 @@
 package nl.andrewl.concord_core.msg;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
-import java.util.List;
 import java.util.UUID;
 
 /**
@@ -14,6 +9,7 @@ import java.util.UUID;
  */
 public class MessageUtils {
 	public static final int UUID_BYTES = 2 * Long.BYTES;
+	public static final int ENUM_BYTES = Integer.BYTES;
 
 	/**
 	 * Gets the number of bytes that the given string will occupy when it is
@@ -26,118 +22,54 @@ public class MessageUtils {
 	}
 
 	/**
-	 * Writes a string to the given output stream using a length-prefixed format
+	 * Gets the number of bytes that all the given strings will occupy when
-	 * where an integer length precedes the string's bytes, which are encoded in
+	 * serialized with a length-prefix encoding.
-	 * UTF-8.
+	 * @param strings The set of strings.
-	 * @param s The string to write.
+	 * @return The total byte size.
-	 * @param o The output stream to write to.
-	 * @throws IOException If the stream could not be written to.
 	 */
-	public static void writeString(String s, DataOutputStream o) throws IOException {
+	public static int getByteSize(String... strings) {
-		if (s == null) {
+		int size = 0;
-			o.writeInt(-1);
+		for (var s : strings) {
-		} else {
+			size += getByteSize(s);
-			o.writeInt(s.length());
-			o.write(s.getBytes(StandardCharsets.UTF_8));
 		}
+		return size;
 	}
 
-	/**
+	public static <T extends Message> int getByteSize(T[] items) {
-	 * Reads a string from the given input stream, using a length-prefixed
-	 * format, where an integer length precedes the string's bytes, which are
-	 * encoded in UTF-8.
-	 * @param i The input stream to read from.
-	 * @return The string which was read.
-	 * @throws IOException If the stream could not be read, or if the string is
-	 * malformed.
-	 */
-	public static String readString(DataInputStream i) throws IOException {
-		int length = i.readInt();
-		if (length == -1) return null;
-		if (length == 0) return "";
-		byte[] data = new byte[length];
-		int read = i.read(data);
-		if (read != length) throw new IOException("Not all bytes of a string of length " + length + " could be read.");
-		return new String(data, StandardCharsets.UTF_8);
-	}
-
-	/**
-	 * Writes an enum value to the given stream as the integer ordinal value of
-	 * the enum value, or -1 if the value is null.
-	 * @param value The value to write.
-	 * @param o The output stream.
-	 * @throws IOException If an error occurs while writing.
-	 */
-	public static void writeEnum(Enum<?> value, DataOutputStream o) throws IOException {
-		if (value == null) {
-			o.writeInt(-1);
-		} else {
-			o.writeInt(value.ordinal());
-		}
-	}
-
-	/**
-	 * Reads an enum value from the given stream, assuming that the value is
-	 * represented by an integer ordinal value.
-	 * @param e The type of enum that is to be read.
-	 * @param i The input stream to read from.
-	 * @param <T> The enum type.
-	 * @return The enum value, or null if -1 was read.
-	 * @throws IOException If an error occurs while reading.
-	 */
-	public static <T extends Enum<?>> T readEnum(Class<T> e, DataInputStream i) throws IOException {
-		int ordinal = i.readInt();
-		if (ordinal == -1) return null;
-		return e.getEnumConstants()[ordinal];
-	}
-
-	public static void writeUUID(UUID value, DataOutputStream o) throws IOException {
-		if (value == null) {
-			o.writeLong(-1);
-			o.writeLong(-1);
-		} else {
-			o.writeLong(value.getMostSignificantBits());
-			o.writeLong(value.getLeastSignificantBits());
-		}
-	}
-
-	public static UUID readUUID(DataInputStream i) throws IOException {
-		long a = i.readLong();
-		long b = i.readLong();
-		if (a == -1 && b == -1) {
-			return null;
-		}
-		return new UUID(a, b);
-	}
-
-	public static int getByteSize(List<? extends Message> items) {
 		int count = Integer.BYTES;
 		for (var item : items) {
-			count += item.getByteCount();
+			count += item.byteSize();
 		}
 		return count;
 	}
 
-	public static void writeList(List<? extends Message> items, DataOutputStream o) throws IOException {
+	public static int getByteSize(Object o) {
-		o.writeInt(items.size());
+		if (o instanceof Integer) {
-		for (var i : items) {
+			return Integer.BYTES;
-			i.write(o);
+		} else if (o instanceof Long) {
+			return Long.BYTES;
+		} else if (o instanceof String) {
+			return getByteSize((String) o);
+		} else if (o instanceof UUID) {
+			return UUID_BYTES;
+		} else if (o instanceof Enum<?>) {
+			return ENUM_BYTES;
+		} else if (o instanceof byte[]) {
+			return Integer.BYTES + ((byte[]) o).length;
+		} else if (o.getClass().isArray() && Message.class.isAssignableFrom(o.getClass().getComponentType())) {
+			return getByteSize((Message[]) o);
+		} else if (o instanceof Message) {
+			return ((Message) o).byteSize();
+		} else {
+			throw new IllegalArgumentException("Unsupported object type: " + o.getClass().getSimpleName());
 		}
 	}
 
-	public static <T extends Message> List<T> readList(Class<T> type, DataInputStream i) throws IOException {
+	public static int getByteSize(Object... objects) {
-		int size = i.readInt();
+		int size = 0;
-		try {
+		for (var o : objects) {
-			var constructor = type.getConstructor();
+			size += getByteSize(o);
-			List<T> items = new ArrayList<>(size);
-			for (int k = 0; k < size; k++) {
-				var item = constructor.newInstance();
-				item.read(i);
-				items.add(item);
-			}
-			return items;
-		} catch (ReflectiveOperationException e) {
-			throw new IOException(e);
 		}
+		return size;
 	}
 }

core/src/main/java/nl/andrewl/concord_core/msg/MessageWriter.java

@@ -0,0 +1,16 @@
+package nl.andrewl.concord_core.msg;
+
+import nl.andrewl.concord_core.util.ChainedDataOutputStream;
+
+import java.io.IOException;
+
+@FunctionalInterface
+public interface MessageWriter<T extends Message> {
+	/**
+	 * Writes this message to the given output stream.
+	 * @param msg The message to write.
+	 * @param out The output stream to write to.
+	 * @throws IOException If an error occurs while writing.
+	 */
+	void write(T msg, ChainedDataOutputStream out) throws IOException;
+}

core/src/main/java/nl/andrewl/concord_core/msg/Serializer.java

@@ -1,9 +1,24 @@
 package nl.andrewl.concord_core.msg;
 
 import nl.andrewl.concord_core.msg.types.Error;
-import nl.andrewl.concord_core.msg.types.*;
+import nl.andrewl.concord_core.msg.types.ServerMetaData;
+import nl.andrewl.concord_core.msg.types.ServerUsers;
+import nl.andrewl.concord_core.msg.types.channel.CreateThread;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryRequest;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryResponse;
+import nl.andrewl.concord_core.msg.types.client_setup.Identification;
+import nl.andrewl.concord_core.msg.types.client_setup.KeyData;
+import nl.andrewl.concord_core.msg.types.client_setup.Registration;
+import nl.andrewl.concord_core.msg.types.client_setup.ServerWelcome;
+import nl.andrewl.concord_core.util.ChainedDataOutputStream;
+import nl.andrewl.concord_core.util.ExtendedDataInputStream;
 
-import java.io.*;
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -17,13 +32,13 @@ public class Serializer {
 	 * The mapping which defines each supported message type and the byte value
 	 * used to identify it when reading and writing messages.
 	 */
-	private final Map<Byte, Class<? extends Message>> messageTypes = new HashMap<>();
+	private final Map<Byte, MessageType<?>> messageTypes = new HashMap<>();
 
 	/**
 	 * An inverse of {@link Serializer#messageTypes} which is used to look up a
 	 * message's byte value when you know the class of the message.
 	 */
-	private final Map<Class<? extends Message>, Byte> inverseMessageTypes = new HashMap<>();
+	private final Map<MessageType<?>, Byte> inverseMessageTypes = new HashMap<>();
 
 	/**
 	 * Constructs a new serializer instance, with a standard set of supported
@@ -36,7 +51,7 @@ public class Serializer {
 		registerType(3, MoveToChannel.class);
 		registerType(4, ChatHistoryRequest.class);
 		registerType(5, ChatHistoryResponse.class);
-		// Type id 6 removed due to deprecation.
+		registerType(6, Registration.class);
 		registerType(7, ServerUsers.class);
 		registerType(8, ServerMetaData.class);
 		registerType(9, Error.class);
@@ -49,12 +64,12 @@ public class Serializer {
 	 * serializer, by adding it to the normal and inverse mappings.
 	 * @param id The byte which will be used to identify messages of the given
 	 *           class. The value should from 0 to 127.
-	 * @param messageClass The class of message which is registered with the
+	 * @param messageClass The type of message associated with the given id.
-	 *                     given byte identifier.
 	 */
-	private synchronized void registerType(int id, Class<? extends Message> messageClass) {
+	private synchronized <T extends Message> void registerType(int id, Class<T> messageClass) {
-		messageTypes.put((byte) id, messageClass);
+		MessageType<T> type = MessageType.get(messageClass);
-		inverseMessageTypes.put(messageClass, (byte) id);
+		messageTypes.put((byte) id, type);
+		inverseMessageTypes.put(type, (byte) id);
 	}
 
 	/**
@@ -67,19 +82,16 @@ public class Serializer {
 	 * constructed for the incoming data.
 	 */
 	public Message readMessage(InputStream i) throws IOException {
-		DataInputStream d = new DataInputStream(i);
+		ExtendedDataInputStream d = new ExtendedDataInputStream(i);
-		byte type = d.readByte();
+		byte typeId = d.readByte();
-		var clazz = messageTypes.get(type);
+		var type = messageTypes.get(typeId);
-		if (clazz == null) {
+		if (type == null) {
-			throw new IOException("Unsupported message type: " + type);
+			throw new IOException("Unsupported message type: " + typeId);
 		}
 		try {
-			var constructor = clazz.getConstructor();
+			return type.reader().read(d);
-			var message = constructor.newInstance();
-			message.read(d);
-			return message;
 		} catch (Throwable e) {
-			throw new IOException("Could not instantiate new message object of type " + clazz.getSimpleName(), e);
+			throw new IOException("Could not instantiate new message object of type " + type.getClass().getSimpleName(), e);
 		}
 	}
 
@@ -90,14 +102,14 @@ public class Serializer {
 	 * @throws IOException If an error occurs while writing, or if the message
 	 * to write is not supported by this serializer.
 	 */
-	public void writeMessage(Message msg, OutputStream o) throws IOException {
+	public <T extends Message> void writeMessage(Message msg, OutputStream o) throws IOException {
 		DataOutputStream d = new DataOutputStream(o);
-		Byte type = inverseMessageTypes.get(msg.getClass());
+		Byte typeId = inverseMessageTypes.get(msg.getType());
-		if (type == null) {
+		if (typeId == null) {
 			throw new IOException("Unsupported message type: " + msg.getClass().getSimpleName());
 		}
-		d.writeByte(type);
+		d.writeByte(typeId);
-		msg.write(d);
+		msg.getType().writer().write(msg, new ChainedDataOutputStream(d));
 		d.flush();
 	}
 }

core/src/main/java/nl/andrewl/concord_core/msg/types/Chat.java

@@ -1,83 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.Objects;
-import java.util.UUID;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
-/**
- * This message contains information about a chat message that a user sent.
- */
-@Data
-@NoArgsConstructor
-@AllArgsConstructor
-public class Chat implements Message {
-	private static final long ID_NONE = 0;
-
-	private UUID id;
-	private UUID senderId;
-	private String senderNickname;
-	private long timestamp;
-	private String message;
-
-	public Chat(UUID senderId, String senderNickname, long timestamp, String message) {
-		this.id = null;
-		this.senderId = senderId;
-		this.senderNickname = senderNickname;
-		this.timestamp = timestamp;
-		this.message = message;
-	}
-
-	public Chat(String message) {
-		this(null, null, System.currentTimeMillis(), message);
-	}
-
-	@Override
-	public int getByteCount() {
-		return 2 * UUID_BYTES + Long.BYTES + getByteSize(this.senderNickname) + getByteSize(this.message);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.id, o);
-		writeUUID(this.senderId, o);
-		writeString(this.senderNickname, o);
-		o.writeLong(this.timestamp);
-		writeString(this.message, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.id = readUUID(i);
-		this.senderId = readUUID(i);
-		this.senderNickname = readString(i);
-		this.timestamp = i.readLong();
-		this.message = readString(i);
-	}
-
-	@Override
-	public String toString() {
-		return String.format("%s: %s", this.senderNickname, this.message);
-	}
-
-	@Override
-	public boolean equals(Object o) {
-		if (o.getClass().equals(this.getClass())) {
-			Chat other = (Chat) o;
-			if (Objects.equals(this.getId(), other.getId())) return true;
-			return this.getSenderId().equals(other.getSenderId()) &&
-					this.getTimestamp() == other.getTimestamp() &&
-					this.getSenderNickname().equals(other.getSenderNickname()) &&
-					this.message.length() == other.message.length();
-		}
-		return false;
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/ChatHistoryResponse.java

@@ -1,43 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.List;
-import java.util.UUID;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
-/**
- * The response that a server sends to a {@link ChatHistoryRequest}. The list of
- * messages is ordered by timestamp, with the newest messages appearing first.
- */
-@Data
-@NoArgsConstructor
-@AllArgsConstructor
-public class ChatHistoryResponse implements Message {
-	private UUID channelId;
-	List<Chat> messages;
-
-	@Override
-	public int getByteCount() {
-		return UUID_BYTES + getByteSize(messages);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.channelId, o);
-		writeList(this.messages, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.channelId = readUUID(i);
-		this.messages = readList(Chat.class, i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/CreateThread.java

@@ -1,56 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.UUID;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
-/**
- * This message is sent by clients when they indicate that they would like to
- * create a new thread in their current channel.
- * <p>
- *     Conversely, this message is also sent by the server when a thread has
- *     been created by someone, and all clients need to be notified so that they
- *     can properly display to the user that a message has been turned into a
- *     thread.
- * </p>
- */
-@Data
-@NoArgsConstructor
-public class CreateThread implements Message {
-	/**
-	 * The id of the message from which the thread will be created. This will
-	 * serve as the entry point of the thread, and the unique identifier for the
-	 * thread.
-	 */
-	private UUID messageId;
-
-	/**
-	 * The title for the thread. This may be null, in which case the thread does
-	 * not have any title.
-	 */
-	private String title;
-
-	@Override
-	public int getByteCount() {
-		return UUID_BYTES + getByteSize(title);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.messageId, o);
-		writeString(this.title, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.messageId = readUUID(i);
-		this.title = readString(i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/Error.java

@@ -1,24 +1,15 @@
 package nl.andrewl.concord_core.msg.types;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
 import nl.andrewl.concord_core.msg.Message;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
 /**
  * Error message which can be sent between either the server or client to
  * indicate an unsavory situation.
  */
-@Data
+public record Error (
-@NoArgsConstructor
+		Level level,
-@AllArgsConstructor
+		String message
-public class Error implements Message {
+) implements Message {
 	/**
 	 * The error level gives an indication as to the severity of the error.
 	 * Warnings indicate that a user has attempted to do something which they
@@ -27,9 +18,6 @@ public class Error implements Message {
 	 */
 	public enum Level {WARNING, ERROR}
 
-	private Level level;
-	private String message;
-
 	public static Error warning(String message) {
 		return new Error(Level.WARNING, message);
 	}
@@ -37,21 +25,4 @@ public class Error implements Message {
 	public static Error error(String message) {
 		return new Error(Level.ERROR, message);
 	}
-
-	@Override
-	public int getByteCount() {
-		return Integer.BYTES + getByteSize(this.message);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeEnum(this.level, o);
-		writeString(this.message, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.level = readEnum(Level.class, i);
-		this.message = readString(i);
-	}
 }

core/src/main/java/nl/andrewl/concord_core/msg/types/Identification.java

@@ -1,56 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
-/**
- * This message is sent from the client to a server, to provide identification
- * information about the client to the server when the connection is started.
- */
-@Data
-@AllArgsConstructor
-@NoArgsConstructor
-public class Identification implements Message {
-	/**
-	 * The nickname that a client wants to be identified by when in the server.
-	 * If a valid session token is provided, this can be left as null, and the
-	 * user will be given the same nickname they had in their previous session.
-	 */
-	private String nickname;
-
-	/**
-	 * A session token that's used to uniquely identify this client as the same
-	 * as one who has previously connected to the server. If this is null, the
-	 * client is indicating that they have not connected to this server before.
-	 */
-	private String sessionToken;
-
-	public Identification(String nickname) {
-		this.nickname = nickname;
-	}
-
-	@Override
-	public int getByteCount() {
-		return getByteSize(this.nickname) + getByteSize(sessionToken);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeString(this.nickname, o);
-		writeString(this.sessionToken, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.nickname = readString(i);
-		this.sessionToken = readString(i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/KeyData.java

@@ -1,52 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.Getter;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-
-/**
- * This message is sent as the first message from both the server and the client
- * to establish an end-to-end encryption via a key exchange.
- */
-@Getter
-@NoArgsConstructor
-public class KeyData implements Message {
-	private byte[] iv;
-	private byte[] salt;
-	private byte[] publicKey;
-
-	public KeyData(byte[] iv, byte[] salt, byte[] publicKey) {
-		this.iv = iv;
-		this.salt = salt;
-		this.publicKey = publicKey;
-	}
-
-	@Override
-	public int getByteCount() {
-		return Integer.BYTES * 3 + iv.length + salt.length + publicKey.length;
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		o.writeInt(iv.length);
-		o.write(iv);
-		o.writeInt(salt.length);
-		o.write(salt);
-		o.writeInt(publicKey.length);
-		o.write(publicKey);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		int ivLength = i.readInt();
-		this.iv = i.readNBytes(ivLength);
-		int saltLength = i.readInt();
-		this.salt = i.readNBytes(saltLength);
-		int publicKeyLength = i.readInt();
-		this.publicKey = i.readNBytes(publicKeyLength);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/MoveToChannel.java

@@ -1,67 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.UUID;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
-/**
- * A message that's sent to a client when they've been moved to another channel.
- * This indicates to the client that they should perform the necessary requests
- * to update their view to indicate that they're now in a different channel.
- * <p>
- *     Conversely, a client can send this request to the server to indicate that
- *     they would like to switch to the specified channel.
- * </p>
- * <p>
- *     Clients can also send this message and provide the id of another client
- *     to request that they enter a private message channel with the referenced
- *     client.
- * </p>
- */
-@Data
-@AllArgsConstructor
-@NoArgsConstructor
-public class MoveToChannel implements Message {
-	/**
-	 * The id of the channel that the client is requesting or being moved to, or
-	 * the id of another client that the user wishes to begin private messaging
-	 * with.
-	 */
-	private UUID id;
-
-	/**
-	 * The name of the channel that the client is moved to. This is null in
-	 * cases where the client is requesting to move to a channel, and is only
-	 * provided by the server when it moves a client.
-	 */
-	private String channelName;
-
-	public MoveToChannel(UUID channelId) {
-		this.id = channelId;
-	}
-
-	@Override
-	public int getByteCount() {
-		return UUID_BYTES + getByteSize(this.channelName);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.id, o);
-		writeString(this.channelName, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.id = readUUID(i);
-		this.channelName = readString(i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/ServerMetaData.java

@@ -1,73 +1,18 @@
 package nl.andrewl.concord_core.msg.types;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
 import nl.andrewl.concord_core.msg.Message;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.List;
 import java.util.UUID;
 
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
 /**
  * Metadata is sent by the server to clients to inform them of the structure of
  * the server. This includes basic information about the server's own properties
  * as well as information about all top-level channels.
  */
-@Data
+public record ServerMetaData (String name, ChannelData[] channels) implements Message {
-@NoArgsConstructor
-@AllArgsConstructor
-public class ServerMetaData implements Message {
-	private String name;
-	private List<ChannelData> channels;
-
-	@Override
-	public int getByteCount() {
-		return getByteSize(this.name) + getByteSize(this.channels);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeString(this.name, o);
-		writeList(this.channels, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.name = readString(i);
-		this.channels = readList(ChannelData.class, i);
-	}
-
 	/**
 	 * Metadata about a top-level channel in the server which is visible and
 	 * joinable for a user.
 	 */
-	@Data
+	public static record ChannelData (UUID id, String name) implements Message {}
-	@NoArgsConstructor
-	@AllArgsConstructor
-	public static class ChannelData implements Message {
-		private UUID id;
-		private String name;
-
-		@Override
-		public int getByteCount() {
-			return UUID_BYTES + getByteSize(this.name);
-		}
-
-		@Override
-		public void write(DataOutputStream o) throws IOException {
-			writeUUID(this.id, o);
-			writeString(this.name, o);
-		}
-
-		@Override
-		public void read(DataInputStream i) throws IOException {
-			this.id = readUUID(i);
-			this.name = readString(i);
-		}
-	}
 }

core/src/main/java/nl/andrewl/concord_core/msg/types/ServerUsers.java

@@ -1,40 +1,10 @@
 package nl.andrewl.concord_core.msg.types;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
 import nl.andrewl.concord_core.msg.Message;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.List;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
 /**
  * This message is sent from the server to the client whenever a change happens
  * which requires the server to notify clients about a change of the list of
  * global users.
  */
-@Data
+public record ServerUsers (UserData[] users) implements Message {}
-@NoArgsConstructor
-@AllArgsConstructor
-public class ServerUsers implements Message {
-	private List<UserData> users;
-
-	@Override
-	public int getByteCount() {
-		return getByteSize(this.users);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeList(this.users, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.users = readList(UserData.class, i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/ServerWelcome.java

@@ -1,72 +0,0 @@
-package nl.andrewl.concord_core.msg.types;
-
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
-import nl.andrewl.concord_core.msg.Message;
-
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
-import java.util.UUID;
-
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
-/**
- * This message is sent from the server to the client after the server accepts
- * the client's identification and registers the client in the server.
- */
-@Data
-@NoArgsConstructor
-@AllArgsConstructor
-public class ServerWelcome implements Message {
-	/**
-	 * The unique id of this client.
-	 */
-	private UUID clientId;
-
-	/**
-	 * The token which this client can use to reconnect to the server later and
-	 * still be recognized as the same user.
-	 */
-	private String sessionToken;
-
-	/**
-	 * The id of the channel that the user has been placed in.
-	 */
-	private UUID currentChannelId;
-
-	/**
-	 * The name of the channel that the user has been placed in.
-	 */
-	private String currentChannelName;
-
-	/**
-	 * Information about the server's structure.
-	 */
-	private ServerMetaData metaData;
-
-	@Override
-	public int getByteCount() {
-		return 2 * UUID_BYTES + getByteSize(this.sessionToken) + getByteSize(this.currentChannelName) + this.metaData.getByteCount();
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.clientId, o);
-		writeString(this.sessionToken, o);
-		writeUUID(this.currentChannelId, o);
-		writeString(this.currentChannelName, o);
-		this.metaData.write(o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.clientId = readUUID(i);
-		this.sessionToken = readString(i);
-		this.currentChannelId = readUUID(i);
-		this.metaData = new ServerMetaData();
-		this.currentChannelName = readString(i);
-		this.metaData.read(i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/UserData.java

@@ -1,43 +1,11 @@
 package nl.andrewl.concord_core.msg.types;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
 import nl.andrewl.concord_core.msg.Message;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
 import java.util.UUID;
 
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-import static nl.andrewl.concord_core.msg.MessageUtils.readString;
-
 /**
  * Standard set of user data that is used mainly as a component of other more
  * complex messages.
  */
-@Data
+public record UserData (UUID id, String name) implements Message {}
-@NoArgsConstructor
-@AllArgsConstructor
-public class UserData implements Message {
-	private UUID id;
-	private String name;
-
-	@Override
-	public int getByteCount() {
-		return UUID_BYTES + getByteSize(this.name);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.id, o);
-		writeString(this.name, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.id = readUUID(i);
-		this.name = readString(i);
-	}
-}

core/src/main/java/nl/andrewl/concord_core/msg/types/channel/CreateThread.java

@@ -0,0 +1,20 @@
+package nl.andrewl.concord_core.msg.types.channel;
+
+import nl.andrewl.concord_core.msg.Message;
+
+import java.util.UUID;
+
+/**
+ * This message is sent by clients when they indicate that they would like to
+ * create a new thread in their current channel.
+ * <p>
+ *     Conversely, this message is also sent by the server when a thread has
+ *     been created by someone, and all clients need to be notified so that they
+ *     can properly display to the user that a message has been turned into a
+ *     thread.
+ * </p>
+ *
+ * @param messageId The id of the message that a thread will be/is attached to.
+ * @param title The title of the thread. This may be null.
+ */
+public record CreateThread (UUID messageId, String title) implements Message {}

core/src/main/java/nl/andrewl/concord_core/msg/types/channel/MoveToChannel.java

@@ -0,0 +1,32 @@
+package nl.andrewl.concord_core.msg.types.channel;
+
+import nl.andrewl.concord_core.msg.Message;
+
+import java.util.UUID;
+
+/**
+ * A message that's sent to a client when they've been moved to another channel.
+ * This indicates to the client that they should perform the necessary requests
+ * to update their view to indicate that they're now in a different channel.
+ * <p>
+ *     Conversely, a client can send this request to the server to indicate that
+ *     they would like to switch to the specified channel.
+ * </p>
+ * <p>
+ *     Clients can also send this message and provide the id of another client
+ *     to request that they enter a private message channel with the referenced
+ *     client.
+ * </p>
+ * @param id The id of the channel that the client is requesting or being moved
+ *           to, or the id of another client that the user wishes to begin
+ *           private messaging with.
+ * @param channelName The name of the channel that the client is moved to. This
+ *                    is null in cases where the client is requesting to move to
+ *                    a channel, and is only provided by the server when it
+ *                    moves a client.
+ */
+public record MoveToChannel (UUID id, String channelName) implements Message {
+	public MoveToChannel(UUID id) {
+		this(id, null);
+	}
+}

core/src/main/java/nl/andrewl/concord_core/msg/types/chat/Chat.java

@@ -0,0 +1,43 @@
+package nl.andrewl.concord_core.msg.types.chat;
+
+import nl.andrewl.concord_core.msg.Message;
+
+import java.util.Objects;
+import java.util.UUID;
+
+/**
+ * This message contains information about a chat message that a user sent.
+ */
+public record Chat (
+		UUID id, UUID senderId, String senderNickname, long timestamp, String message
+) implements Message {
+	public Chat(UUID senderId, String senderNickname, long timestamp, String message) {
+		this(null, senderId, senderNickname, timestamp, message);
+	}
+
+	public Chat(String message) {
+		this(null, null, System.currentTimeMillis(), message);
+	}
+
+	public Chat(UUID newId, Chat original) {
+		this(newId, original.senderId, original.senderNickname, original.timestamp, original.message);
+	}
+
+	@Override
+	public String toString() {
+		return String.format("%s: %s", this.senderNickname, this.message);
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (o.getClass().equals(this.getClass())) {
+			Chat other = (Chat) o;
+			if (Objects.equals(this.id, other.id)) return true;
+			return this.senderId.equals(other.senderId) &&
+					this.timestamp == other.timestamp &&
+					this.senderNickname.equals(other.senderNickname) &&
+					this.message.length() == other.message.length();
+		}
+		return false;
+	}
+}

core/src/main/java/nl/andrewl/concord_core/msg/types/chat/ChatHistoryRequest.java

@@ -1,20 +1,12 @@
-package nl.andrewl.concord_core.msg.types;
+package nl.andrewl.concord_core.msg.types.chat;
 
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.NoArgsConstructor;
 import nl.andrewl.concord_core.msg.Message;
 
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
-import static nl.andrewl.concord_core.msg.MessageUtils.*;
-
 /**
  * A message which clients can send to the server to request some messages from
  * the server's history of all sent messages from a particular source. Every
@@ -51,20 +43,15 @@ import static nl.andrewl.concord_core.msg.MessageUtils.*;
  *     the list of messages is always sorted by the timestamp.
  * </p>
  */
-@Data
+public record ChatHistoryRequest (UUID channelId, String query) implements Message {
-@NoArgsConstructor
-@AllArgsConstructor
-public class ChatHistoryRequest implements Message {
-	private UUID channelId;
-	private String query;
-
 	public ChatHistoryRequest(UUID channelId) {
 		this(channelId, "");
 	}
 
 	public ChatHistoryRequest(UUID channelId, Map<String, String> params) {
-		this.channelId = channelId;
+		this(
-		this.query = params.entrySet().stream()
+			channelId,
+			params.entrySet().stream()
 				.map(entry -> {
 					if (entry.getKey().contains(";") || entry.getKey().contains("=")) {
 						throw new IllegalArgumentException("Parameter key \"" + entry.getKey() + "\" contains invalid characters.");
@@ -74,7 +61,8 @@ public class ChatHistoryRequest implements Message {
 					}
 					return entry.getKey() + "=" + entry.getValue();
 				})
-				.collect(Collectors.joining(";"));
+				.collect(Collectors.joining(";"))
+		);
 	}
 
 	/**
@@ -92,21 +80,4 @@ public class ChatHistoryRequest implements Message {
 		}
 		return params;
 	}
-
-	@Override
-	public int getByteCount() {
-		return UUID_BYTES + getByteSize(this.query);
-	}
-
-	@Override
-	public void write(DataOutputStream o) throws IOException {
-		writeUUID(this.channelId, o);
-		writeString(this.query, o);
-	}
-
-	@Override
-	public void read(DataInputStream i) throws IOException {
-		this.channelId = readUUID(i);
-		this.query = readString(i);
-	}
 }

core/src/main/java/nl/andrewl/concord_core/msg/types/chat/ChatHistoryResponse.java

@@ -0,0 +1,11 @@
+package nl.andrewl.concord_core.msg.types.chat;
+
+import nl.andrewl.concord_core.msg.Message;
+
+import java.util.UUID;
+
+/**
+ * The response that a server sends to a {@link ChatHistoryRequest}. The list of
+ * messages is ordered by timestamp, with the newest messages appearing first.
+ */
+public record ChatHistoryResponse (UUID channelId, Chat[] messages) implements Message {}

core/src/main/java/nl/andrewl/concord_core/msg/types/client_setup/Identification.java

@@ -0,0 +1,11 @@
+package nl.andrewl.concord_core.msg.types.client_setup;
+
+import nl.andrewl.concord_core.msg.Message;
+
+/**
+ * This message is sent from the client to a server, to provide identification
+ * information about the client to the server when the connection is started.
+ *
+ * @param nickname
+ */
+public record Identification(String nickname, String sessionToken) implements Message {}

core/src/main/java/nl/andrewl/concord_core/msg/types/client_setup/KeyData.java

@@ -0,0 +1,9 @@
+package nl.andrewl.concord_core.msg.types.client_setup;
+
+import nl.andrewl.concord_core.msg.Message;
+
+/**
+ * This message is sent as the first message from both the server and the client
+ * to establish an end-to-end encryption via a key exchange.
+ */
+public record KeyData (byte[] iv, byte[] salt, byte[] publicKey) implements Message {}

core/src/main/java/nl/andrewl/concord_core/msg/types/client_setup/Registration.java

@@ -0,0 +1,9 @@
+package nl.andrewl.concord_core.msg.types.client_setup;
+
+import nl.andrewl.concord_core.msg.Message;
+
+/**
+ * The data that new users should send to a server in order to register in that
+ * server.
+ */
+public record Registration (String username, String password) implements Message {}

core/src/main/java/nl/andrewl/concord_core/msg/types/client_setup/ServerWelcome.java

@@ -0,0 +1,25 @@
+package nl.andrewl.concord_core.msg.types.client_setup;
+
+import nl.andrewl.concord_core.msg.Message;
+import nl.andrewl.concord_core.msg.types.ServerMetaData;
+
+import java.util.UUID;
+
+/**
+ * This message is sent from the server to the client after the server accepts
+ * the client's identification and registers the client in the server.
+ *
+ * @param clientId The unique id of this client.
+ * @param sessionToken The token which this client can use to reconnect to the
+ *                     server later and still be recognized as the same user.
+ * @param currentChannelId The id of the channel that the user is placed in.
+ * @param currentChannelName The name of the channel that the user is placed in.
+ * @param metaData Information about the server's structure.
+ */
+public record ServerWelcome (
+		UUID clientId,
+		String sessionToken,
+		UUID currentChannelId,
+		String currentChannelName,
+		ServerMetaData metaData
+) implements Message {}

core/src/main/java/nl/andrewl/concord_core/util/ChainedDataOutputStream.java

@@ -0,0 +1,108 @@
+package nl.andrewl.concord_core.util;
+
+import nl.andrewl.concord_core.msg.Message;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.UUID;
+
+/**
+ * A more complex output stream which redefines certain methods for convenience
+ * with method chaining.
+ */
+public class ChainedDataOutputStream {
+	private final DataOutputStream out;
+
+	public ChainedDataOutputStream(DataOutputStream out) {
+		this.out = out;
+	}
+
+	public ChainedDataOutputStream writeInt(int x) throws IOException {
+		out.writeInt(x);
+		return this;
+	}
+
+	public ChainedDataOutputStream writeString(String s) throws IOException {
+		if (s == null) {
+			out.writeInt(-1);
+		} else {
+			out.writeInt(s.length());
+			out.write(s.getBytes(StandardCharsets.UTF_8));
+		}
+		return this;
+	}
+
+	public ChainedDataOutputStream writeStrings(String... strings) throws IOException {
+		for (var s : strings) {
+			writeString(s);
+		}
+		return this;
+	}
+
+	public ChainedDataOutputStream writeEnum(Enum<?> value) throws IOException {
+		if (value == null) {
+			out.writeInt(-1);
+		} else {
+			out.writeInt(value.ordinal());
+		}
+		return this;
+	}
+
+	public ChainedDataOutputStream writeUUID(UUID uuid) throws IOException {
+		if (uuid == null) {
+			out.writeLong(-1);
+			out.writeLong(-1);
+		} else {
+			out.writeLong(uuid.getMostSignificantBits());
+			out.writeLong(uuid.getLeastSignificantBits());
+		}
+		return this;
+	}
+
+	public <T extends Message> ChainedDataOutputStream writeArray(T[] array) throws IOException {
+		this.out.writeInt(array.length);
+		for (var item : array) {
+			item.getType().writer().write(item, this);
+		}
+		return this;
+	}
+
+	public <T extends Message> ChainedDataOutputStream writeMessage(Message msg) throws IOException {
+		msg.getType().writer().write(msg, this);
+		return this;
+	}
+
+	/**
+	 * Writes an object to the stream.
+	 * @param o The object to write.
+	 * @param type The object's type. This is needed in case the object itself
+	 *             is null, which may be the case for some strings or ids.
+	 * @return The chained output stream.
+	 * @throws IOException If an error occurs.
+	 */
+	public ChainedDataOutputStream writeObject(Object o, Class<?> type) throws IOException {
+		if (type.equals(Integer.class) || type.equals(int.class)) {
+			this.writeInt((Integer) o);
+		} else if (type.equals(Long.class) || type.equals(long.class)) {
+			this.out.writeLong((Long) o);
+		} else if (type.equals(String.class)) {
+			this.writeString((String) o);
+		} else if (type.equals(UUID.class)) {
+			this.writeUUID((UUID) o);
+		} else if (type.isEnum()) {
+			this.writeEnum((Enum<?>) o);
+		} else if (type.equals(byte[].class)) {
+			byte[] b = (byte[]) o;
+			this.writeInt(b.length);
+			this.out.write(b);
+		} else if (type.isArray() && Message.class.isAssignableFrom(type.getComponentType())) {
+			this.writeArray((Message[]) o);
+		} else if (Message.class.isAssignableFrom(type)) {
+			this.writeMessage((Message) o);
+		} else {
+			throw new IOException("Unsupported object type: " + o.getClass().getSimpleName());
+		}
+		return this;
+	}
+}

core/src/main/java/nl/andrewl/concord_core/util/ExtendedDataInputStream.java

@@ -0,0 +1,88 @@
+package nl.andrewl.concord_core.util;
+
+import nl.andrewl.concord_core.msg.Message;
+import nl.andrewl.concord_core.msg.MessageType;
+
+import java.io.DataInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.lang.reflect.Array;
+import java.nio.charset.StandardCharsets;
+import java.util.UUID;
+
+/**
+ * An extended output stream which contains additional methods for reading more
+ * complex types that are used by the Concord system.
+ */
+public class ExtendedDataInputStream extends DataInputStream {
+	public ExtendedDataInputStream(InputStream in) {
+		super(in);
+	}
+
+	public String readString() throws IOException {
+		int length = super.readInt();
+		if (length == -1) return null;
+		if (length == 0) return "";
+		byte[] data = new byte[length];
+		int read = super.read(data);
+		if (read != length) throw new IOException("Not all bytes of a string of length " + length + " could be read.");
+		return new String(data, StandardCharsets.UTF_8);
+	}
+
+	public <T extends Enum<?>> T readEnum(Class<T> e) throws IOException {
+		int ordinal = super.readInt();
+		if (ordinal == -1) return null;
+		return e.getEnumConstants()[ordinal];
+	}
+
+	public UUID readUUID() throws IOException {
+		long a = super.readLong();
+		long b = super.readLong();
+		if (a == -1 && b == -1) {
+			return null;
+		}
+		return new UUID(a, b);
+	}
+
+	@SuppressWarnings("unchecked")
+	public <T extends Message> T[] readArray(MessageType<T> type) throws IOException {
+		int length = super.readInt();
+		T[] array = (T[]) Array.newInstance(type.messageClass(), length);
+		for (int i = 0; i < length; i++) {
+			array[i] = type.reader().read(this);
+		}
+		return array;
+	}
+
+	/**
+	 * Reads an object from the stream that is of a certain expected type.
+	 * @param type The type of object to read.
+	 * @return The object that was read.
+	 * @throws IOException If an error occurs while reading.
+	 */
+	@SuppressWarnings("unchecked")
+	public Object readObject(Class<?> type) throws IOException {
+		if (type.equals(Integer.class) || type.equals(int.class)) {
+			return this.readInt();
+		} else if (type.equals(Long.class) || type.equals(long.class)) {
+			return this.readLong();
+		} else if (type.equals(String.class)) {
+			return this.readString();
+		} else if (type.equals(UUID.class)) {
+			return this.readUUID();
+		} else if (type.isEnum()) {
+			return this.readEnum((Class<? extends Enum<?>>) type);
+		} else if (type.isAssignableFrom(byte[].class)) {
+			int length = this.readInt();
+			return this.readNBytes(length);
+		} else if (type.isArray() && Message.class.isAssignableFrom(type.getComponentType())) {
+			var messageType = MessageType.get((Class<? extends Message>) type.getComponentType());
+			return this.readArray(messageType);
+		} else if (Message.class.isAssignableFrom(type)) {
+			var messageType = MessageType.get((Class<? extends Message>) type);
+			return messageType.reader().read(this);
+		} else {
+			throw new IOException("Unsupported object type: " + type.getSimpleName());
+		}
+	}
+}

core/src/main/java/nl/andrewl/concord_core/util/Triple.java

@@ -0,0 +1,3 @@
+package nl.andrewl.concord_core.util;
+
+public record Triple<A, B, C> (A first, B second, C third) {}

server/src/main/java/nl/andrewl/concord_server/ConcordServer.java

@@ -22,7 +22,6 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
-import java.util.stream.Collectors;
 
 /**
  * The main server implementation, which handles accepting new clients.
@@ -128,8 +127,8 @@ public class ConcordServer implements Runnable {
 				this.config.getName(),
 				this.channelManager.getChannels().stream()
 						.map(channel -> new ServerMetaData.ChannelData(channel.getId(), channel.getName()))
-						.sorted(Comparator.comparing(ServerMetaData.ChannelData::getName))
+						.sorted(Comparator.comparing(ServerMetaData.ChannelData::name))
-						.collect(Collectors.toList())
+						.toList().toArray(new ServerMetaData.ChannelData[0])
 		);
 	}
 

server/src/main/java/nl/andrewl/concord_server/channel/Channel.java

@@ -76,7 +76,7 @@ public class Channel implements Comparable<Channel> {
 	 * @throws IOException If an error occurs.
 	 */
 	public void sendMessage(Message msg) throws IOException {
-		ByteArrayOutputStream baos = new ByteArrayOutputStream(msg.getByteCount() + 1);
+		ByteArrayOutputStream baos = new ByteArrayOutputStream(msg.byteSize() + 1);
 		this.server.getSerializer().writeMessage(msg, baos);
 		byte[] data = baos.toByteArray();
 		for (var client : this.connectedClients) {
@@ -93,7 +93,7 @@ public class Channel implements Comparable<Channel> {
 		for (var clientThread : this.getConnectedClients()) {
 			users.add(clientThread.toData());
 		}
-		users.sort(Comparator.comparing(UserData::getName));
+		users.sort(Comparator.comparing(UserData::name));
 		return users;
 	}
 

server/src/main/java/nl/andrewl/concord_server/channel/ChannelManager.java

@@ -1,6 +1,6 @@
 package nl.andrewl.concord_server.channel;
 
-import nl.andrewl.concord_core.msg.types.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.client.ClientThread;
 import nl.andrewl.concord_server.util.CollectionUtils;

server/src/main/java/nl/andrewl/concord_server/cli/command/ListClientsCommand.java

@@ -15,7 +15,7 @@ public class ListClientsCommand implements ServerCliCommand {
 		} else {
 			StringBuilder sb = new StringBuilder("Online Users:\n");
 			for (var userData : users) {
-				sb.append("\t").append(userData.getName()).append(" (").append(userData.getId()).append(")\n");
+				sb.append("\t").append(userData.name()).append(" (").append(userData.id()).append(")\n");
 			}
 			System.out.print(sb);
 		}

server/src/main/java/nl/andrewl/concord_server/client/ClientManager.java

@@ -2,7 +2,10 @@ package nl.andrewl.concord_server.client;
 
 import nl.andrewl.concord_core.msg.Message;
 import nl.andrewl.concord_core.msg.types.Error;
-import nl.andrewl.concord_core.msg.types.*;
+import nl.andrewl.concord_core.msg.types.ServerUsers;
+import nl.andrewl.concord_core.msg.types.UserData;
+import nl.andrewl.concord_core.msg.types.client_setup.Identification;
+import nl.andrewl.concord_core.msg.types.client_setup.ServerWelcome;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.util.CollectionUtils;
 import nl.andrewl.concord_server.util.StringUtils;
@@ -54,7 +57,7 @@ public class ClientManager {
 	public void handleLogIn(Identification identification, ClientThread clientThread) {
 		ClientConnectionData data;
 		try {
-			data = identification.getSessionToken() == null ? getNewClientData(identification) : getClientDataFromDb(identification);
+			data = identification.sessionToken() == null ? getNewClientData(identification) : getClientDataFromDb(identification);
 		} catch (InvalidIdentificationException e) {
 			clientThread.sendToClient(Error.warning(e.getMessage()));
 			return;
@@ -75,7 +78,7 @@ public class ClientManager {
 				data.newClient ? " for the first time" : "",
 				defaultChannel
 		);
-		this.broadcast(new ServerUsers(this.getClients()));
+		this.broadcast(new ServerUsers(this.getClients().toArray(new UserData[0])));
 	}
 
 	/**
@@ -89,7 +92,7 @@ public class ClientManager {
 			client.getCurrentChannel().removeClient(client);
 			client.shutdown();
 			System.out.println("Client " + client + " has disconnected.");
-			this.broadcast(new ServerUsers(this.getClients()));
+			this.broadcast(new ServerUsers(this.getClients().toArray(new UserData[0])));
 		}
 	}
 
@@ -99,7 +102,7 @@ public class ClientManager {
 	 * @param message The message to send.
 	 */
 	public void broadcast(Message message) {
-		ByteArrayOutputStream baos = new ByteArrayOutputStream(message.getByteCount());
+		ByteArrayOutputStream baos = new ByteArrayOutputStream(message.byteSize());
 		try {
 			this.server.getSerializer().writeMessage(message, baos);
 			byte[] data = baos.toByteArray();
@@ -129,11 +132,11 @@ public class ClientManager {
 	private static record ClientConnectionData(UUID id, String nickname, String sessionToken, boolean newClient) {}
 
 	private ClientConnectionData getClientDataFromDb(Identification identification) throws InvalidIdentificationException {
-		var cursor = this.userCollection.find(Filters.eq("sessionToken", identification.getSessionToken()));
+		var cursor = this.userCollection.find(Filters.eq("sessionToken", identification.sessionToken()));
 		Document doc = cursor.firstOrDefault();
 		if (doc != null) {
 			UUID id = doc.get("id", UUID.class);
-			String nickname = identification.getNickname();
+			String nickname = identification.nickname();
 			if (nickname != null) {
 				doc.put("nickname", nickname);
 			} else {
@@ -150,7 +153,7 @@ public class ClientManager {
 
 	private ClientConnectionData getNewClientData(Identification identification) throws InvalidIdentificationException {
 		UUID id = this.server.getIdProvider().newId();
-		String nickname = identification.getNickname();
+		String nickname = identification.nickname();
 		if (nickname == null) {
 			throw new InvalidIdentificationException("Missing nickname.");
 		}

server/src/main/java/nl/andrewl/concord_server/client/ClientThread.java

@@ -4,7 +4,7 @@ import lombok.Getter;
 import lombok.Setter;
 import nl.andrewl.concord_core.msg.Encryption;
 import nl.andrewl.concord_core.msg.Message;
-import nl.andrewl.concord_core.msg.types.Identification;
+import nl.andrewl.concord_core.msg.types.client_setup.Identification;
 import nl.andrewl.concord_core.msg.types.UserData;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.channel.Channel;

server/src/main/java/nl/andrewl/concord_server/event/ChannelMoveHandler.java

@@ -1,11 +1,10 @@
 package nl.andrewl.concord_server.event;
 
 import nl.andrewl.concord_core.msg.types.Error;
-import nl.andrewl.concord_core.msg.types.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.client.ClientThread;
 
-import java.util.List;
 import java.util.Set;
 
 /**
@@ -17,11 +16,11 @@ import java.util.Set;
 public class ChannelMoveHandler implements MessageHandler<MoveToChannel> {
 	@Override
 	public void handle(MoveToChannel msg, ClientThread client, ConcordServer server) {
-		var optionalChannel = server.getChannelManager().getChannelById(msg.getId());
+		var optionalChannel = server.getChannelManager().getChannelById(msg.id());
 		if (optionalChannel.isPresent()) {
 			server.getChannelManager().moveToChannel(client, optionalChannel.get());
 		} else {
-			var optionalClient = server.getClientManager().getClientById(msg.getId());
+			var optionalClient = server.getClientManager().getClientById(msg.id());
 			if (optionalClient.isPresent()) {
 				var privateChannel = server.getChannelManager().getPrivateChannel(Set.of(
 						client.getClientId(),

server/src/main/java/nl/andrewl/concord_server/event/ChatHandler.java

@@ -1,7 +1,7 @@
 package nl.andrewl.concord_server.event;
 
-import nl.andrewl.concord_core.msg.types.Chat;
 import nl.andrewl.concord_core.msg.types.Error;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.client.ClientThread;
 import org.dizitart.no2.Document;
@@ -17,7 +17,7 @@ import java.util.Map;
 public class ChatHandler implements MessageHandler<Chat> {
 	@Override
 	public void handle(Chat msg, ClientThread client, ConcordServer server) throws IOException {
-		if (msg.getMessage().length() > server.getConfig().getMaxMessageLength()) {
+		if (msg.message().length() > server.getConfig().getMaxMessageLength()) {
 			client.getCurrentChannel().sendMessage(Error.warning("Message is too long."));
 			return;
 		}
@@ -27,17 +27,17 @@ public class ChatHandler implements MessageHandler<Chat> {
 		malicious UUID, so we overwrite it with a server-generated id which we
 		know is safe.
 		 */
-		msg.setId(server.getIdProvider().newId());
+		msg = new Chat(server.getIdProvider().newId(), msg);
 		var collection = client.getCurrentChannel().getMessageCollection();
 		Document doc = new Document(Map.of(
-				"id", msg.getId(),
+				"id", msg.id(),
-				"senderId", msg.getSenderId(),
+				"senderId", msg.senderId(),
-				"senderNickname", msg.getSenderNickname(),
+				"senderNickname", msg.senderNickname(),
-				"timestamp", msg.getTimestamp(),
+				"timestamp", msg.timestamp(),
-				"message", msg.getMessage()
+				"message", msg.message()
 		));
 		collection.insert(doc);
-		System.out.printf("#%s | %s: %s\n", client.getCurrentChannel(), client.getClientNickname(), msg.getMessage());
+		System.out.printf("#%s | %s: %s\n", client.getCurrentChannel(), client.getClientNickname(), msg.message());
 		client.getCurrentChannel().sendMessage(msg);
 	}
 }

server/src/main/java/nl/andrewl/concord_server/event/ChatHistoryRequestHandler.java

@@ -1,9 +1,9 @@
 package nl.andrewl.concord_server.event;
 
-import nl.andrewl.concord_core.msg.types.Chat;
-import nl.andrewl.concord_core.msg.types.ChatHistoryRequest;
-import nl.andrewl.concord_core.msg.types.ChatHistoryResponse;
 import nl.andrewl.concord_core.msg.types.Error;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryRequest;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryResponse;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.channel.Channel;
 import nl.andrewl.concord_server.client.ClientThread;
@@ -19,10 +19,10 @@ public class ChatHistoryRequestHandler implements MessageHandler<ChatHistoryRequ
 	@Override
 	public void handle(ChatHistoryRequest msg, ClientThread client, ConcordServer server) {
 		// First try and find a public channel with the given id.
-		var channel = server.getChannelManager().getChannelById(msg.getChannelId()).orElse(null);
+		var channel = server.getChannelManager().getChannelById(msg.channelId()).orElse(null);
 		if (channel == null) {
 			// Couldn't find a public channel, so look for a private channel this client is involved in.
-			channel = server.getChannelManager().getPrivateChannel(client.getClientId(), msg.getChannelId()).orElse(null);
+			channel = server.getChannelManager().getPrivateChannel(client.getClientId(), msg.channelId()).orElse(null);
 		}
 		// If we couldn't find a public or private channel, give up.
 		if (channel == null) {
@@ -55,7 +55,7 @@ public class ChatHistoryRequestHandler implements MessageHandler<ChatHistoryRequ
 		for (var doc : cursor) {
 			chats.add(this.read(doc));
 		}
-		client.sendToClient(new ChatHistoryResponse(channel.getId(), chats));
+		client.sendToClient(new ChatHistoryResponse(channel.getId(), chats.toArray(new Chat[0])));
 	}
 
 	/**
@@ -89,7 +89,7 @@ public class ChatHistoryRequestHandler implements MessageHandler<ChatHistoryRequ
 			chats.add(this.read(doc));
 		}
 		Collections.reverse(chats);
-		return new ChatHistoryResponse(channel.getId(), chats);
+		return new ChatHistoryResponse(channel.getId(), chats.toArray(new Chat[0]));
 	}
 
 	/**

server/src/main/java/nl/andrewl/concord_server/event/EventManager.java

@@ -2,9 +2,9 @@ package nl.andrewl.concord_server.event;
 
 import lombok.extern.java.Log;
 import nl.andrewl.concord_core.msg.Message;
-import nl.andrewl.concord_core.msg.types.Chat;
+import nl.andrewl.concord_core.msg.types.chat.Chat;
-import nl.andrewl.concord_core.msg.types.ChatHistoryRequest;
+import nl.andrewl.concord_core.msg.types.chat.ChatHistoryRequest;
-import nl.andrewl.concord_core.msg.types.MoveToChannel;
+import nl.andrewl.concord_core.msg.types.channel.MoveToChannel;
 import nl.andrewl.concord_server.ConcordServer;
 import nl.andrewl.concord_server.client.ClientThread;