diff --git a/ChatApp/.gitignore b/ChatApp/.gitignore
new file mode 100644
index 0000000..8e0825e
--- /dev/null
+++ b/ChatApp/.gitignore
@@ -0,0 +1,3 @@
+.vscode
+bin
+lib
\ No newline at end of file
diff --git a/ChatApp/README.md b/ChatApp/README.md
new file mode 100644
index 0000000..7c03a53
--- /dev/null
+++ b/ChatApp/README.md
@@ -0,0 +1,18 @@
+## Getting Started
+
+Welcome to the VS Code Java world. Here is a guideline to help you get started to write Java code in Visual Studio Code.
+
+## Folder Structure
+
+The workspace contains two folders by default, where:
+
+- `src`: the folder to maintain sources
+- `lib`: the folder to maintain dependencies
+
+Meanwhile, the compiled output files will be generated in the `bin` folder by default.
+
+> If you want to customize the folder structure, open `.vscode/settings.json` and update the related settings there.
+
+## Dependency Management
+
+The `JAVA PROJECTS` view allows you to manage your dependencies. More details can be found [here](https://github.com/microsoft/vscode-java-dependency#manage-dependencies).
diff --git a/ChatApp/src/App.java b/ChatApp/src/App.java
new file mode 100644
index 0000000..0a839f9
--- /dev/null
+++ b/ChatApp/src/App.java
@@ -0,0 +1,5 @@
+public class App {
+    public static void main(String[] args) throws Exception {
+        System.out.println("Hello, World!");
+    }
+}
diff --git a/ChatApp/src/network/protocol/Packet.java b/ChatApp/src/network/protocol/Packet.java
new file mode 100644
index 0000000..dc1d7f2
--- /dev/null
+++ b/ChatApp/src/network/protocol/Packet.java
@@ -0,0 +1,9 @@
+package network.protocol;
+
+import java.io.Serializable;
+
+public abstract class Packet implements Serializable {
+
+	public abstract void accept(PacketVisitor packetVisitor);
+
+}
diff --git a/ChatApp/src/network/protocol/PacketVisitor.java b/ChatApp/src/network/protocol/PacketVisitor.java
new file mode 100644
index 0000000..d073f6a
--- /dev/null
+++ b/ChatApp/src/network/protocol/PacketVisitor.java
@@ -0,0 +1,29 @@
+package network.protocol;
+
+import network.protocol.packets.ChatMessagePacket;
+import network.protocol.packets.CreateRoomPacket;
+import network.protocol.packets.JoinRoomPacket;
+import network.protocol.packets.LeaveRoomPacket;
+import network.protocol.packets.LoginPacket;
+import network.protocol.packets.RequestRoomListPacket;
+import network.protocol.packets.RoomListPacket;
+import network.protocol.packets.SendChatMessagePacket;
+import network.protocol.packets.ServerResponsePacket;
+
+public interface PacketVisitor {
+
+	default void visit(Packet packet) {
+		packet.accept(this);
+	}
+	
+	void visitPacket(ChatMessagePacket packet);
+	void visitPacket(CreateRoomPacket packet);
+	void visitPacket(JoinRoomPacket packet);
+	void visitPacket(LeaveRoomPacket packet);
+	void visitPacket(LoginPacket packet);
+	void visitPacket(RequestRoomListPacket packet);
+	void visitPacket(RoomListPacket packet);
+	void visitPacket(SendChatMessagePacket packet);
+	void visitPacket(ServerResponsePacket packet);
+	
+}
diff --git a/ChatApp/src/network/protocol/Packets.java b/ChatApp/src/network/protocol/Packets.java
new file mode 100644
index 0000000..8a1effb
--- /dev/null
+++ b/ChatApp/src/network/protocol/Packets.java
@@ -0,0 +1,15 @@
+package network.protocol;
+
+public enum Packets {
+
+	ChatMessage, 
+	CreateRoom, 
+	JoinRoom, 
+	LeaveRoom, 
+	Login,
+	RequestRoom,
+	Response,
+	RoomList, 
+	SendChatMessage, 
+
+}
\ No newline at end of file
diff --git a/ChatApp/src/network/protocol/packets/ChatMessagePacket.java b/ChatApp/src/network/protocol/packets/ChatMessagePacket.java
new file mode 100644
index 0000000..ee79aeb
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/ChatMessagePacket.java
@@ -0,0 +1,40 @@
+package network.protocol.packets;
+
+import java.time.Instant;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class ChatMessagePacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	private final Instant time;
+	private final String chatter;
+	private final String content;
+
+	public ChatMessagePacket(Instant time, String chatter, String content) {
+		this.time = time;
+		this.chatter = chatter;
+		this.content = content;
+	}
+
+	public Instant getTime() {
+		return time;
+	}
+
+	public String getChatter() {
+		return chatter;
+	}
+
+	public String getContent() {
+		return content;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/CreateRoomPacket.java b/ChatApp/src/network/protocol/packets/CreateRoomPacket.java
new file mode 100644
index 0000000..046a7b5
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/CreateRoomPacket.java
@@ -0,0 +1,26 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class CreateRoomPacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	private final String roomName;
+
+	public CreateRoomPacket(String roomName) {
+		this.roomName = roomName;
+	}
+
+	public String getRoomName() {
+		return roomName;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/JoinRoomPacket.java b/ChatApp/src/network/protocol/packets/JoinRoomPacket.java
new file mode 100644
index 0000000..a3b3173
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/JoinRoomPacket.java
@@ -0,0 +1,26 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class JoinRoomPacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	private final String roomName;
+
+	public JoinRoomPacket(String roomName) {
+		this.roomName = roomName;
+	}
+
+	public String getRoomName() {
+		return roomName;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/LeaveRoomPacket.java b/ChatApp/src/network/protocol/packets/LeaveRoomPacket.java
new file mode 100644
index 0000000..2200dc8
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/LeaveRoomPacket.java
@@ -0,0 +1,19 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class LeaveRoomPacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	public LeaveRoomPacket() {
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/LoginPacket.java b/ChatApp/src/network/protocol/packets/LoginPacket.java
new file mode 100644
index 0000000..237dd3f
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/LoginPacket.java
@@ -0,0 +1,26 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class LoginPacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	private final String pseudo;
+
+	public LoginPacket(String pseudo) {
+		this.pseudo = pseudo;
+	}
+
+	public String getPseudo() {
+		return pseudo;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/RequestRoomListPacket.java b/ChatApp/src/network/protocol/packets/RequestRoomListPacket.java
new file mode 100644
index 0000000..da267ba
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/RequestRoomListPacket.java
@@ -0,0 +1,20 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class RequestRoomListPacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+
+	public RequestRoomListPacket() {
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/RoomListPacket.java b/ChatApp/src/network/protocol/packets/RoomListPacket.java
new file mode 100644
index 0000000..1ee7008
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/RoomListPacket.java
@@ -0,0 +1,28 @@
+package network.protocol.packets;
+
+import java.util.ArrayList;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class RoomListPacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	private final ArrayList<String> roomNames;
+
+	public RoomListPacket(ArrayList<String> roomNames) {
+		this.roomNames = roomNames;
+	}
+
+	public ArrayList<String> getRoomNames() {
+		return roomNames;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/SendChatMessagePacket.java b/ChatApp/src/network/protocol/packets/SendChatMessagePacket.java
new file mode 100644
index 0000000..52a6b0b
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/SendChatMessagePacket.java
@@ -0,0 +1,26 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class SendChatMessagePacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	private final String content;
+
+	public SendChatMessagePacket(String content) {
+		this.content = content;
+	}
+
+	public String getContent() {
+		return content;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}
diff --git a/ChatApp/src/network/protocol/packets/ServerResponsePacket.java b/ChatApp/src/network/protocol/packets/ServerResponsePacket.java
new file mode 100644
index 0000000..e45f73d
--- /dev/null
+++ b/ChatApp/src/network/protocol/packets/ServerResponsePacket.java
@@ -0,0 +1,30 @@
+package network.protocol.packets;
+
+import network.protocol.Packet;
+import network.protocol.PacketVisitor;
+import network.protocol.Packets;
+
+public class ServerResponsePacket extends Packet {
+
+	static private final long serialVersionUID = Packets.Login.ordinal();
+
+	public static enum Response {
+		AuthSuccess, AuthError, RoomCreated, RoomNotCreated, RoomJoined, RoomNotJoined, NotInRoom;
+	};
+
+	private final Response response;
+
+	public ServerResponsePacket(Response response) {
+		this.response = response;
+	}
+
+	public Response getResponse() {
+		return response;
+	}
+
+	@Override
+	public void accept(PacketVisitor packetVisitor) {
+		packetVisitor.visitPacket(this);
+	}
+
+}