Thread Chat — TCP Client/Server

A simple two-client chat service over TCP. This repo includes:

• A Dockerized setup for an automated demo with scripted clients.
• An interactive (individualized) Docker workflow where each client runs in its own terminal.
• A Mininet walkthrough for running the server and two clients on separate hosts in an Oracle VirtualBox Linux VM with Mininet.

Repository Layout

Thread_Chat/
├─ dockerized_version/
│  ├─ chat_server.py
│  ├─ chat_client.py
│  ├─ scripted_client.py
│  ├─ docker-compose.yml
│  ├─ Dockerfile
│  ├─ scripts/
│  │  ├─ client1_messages.txt
│  │  └─ client2_messages.txt
│  ├─ Makefile                # optional convenience aliases
│  └─ tmux_interactive.sh     # tmux helper for split-pane runs
└─ oracle_vm_mininet_version/
├─ chat_server.py
└─ chat_client.py

Default server port: 12000/TCP.

Prerequisites

• Docker Desktop with Compose v2 enabled (Windows/macOS) or Docker Engine + Compose plugin (Linux).
• PowerShell (Windows) or Git Bash / WSL bash (Windows) or any bash shell (macOS/Linux).
• Python 3.11+ is baked into the containers. For Mininet runs you’ll need Python 3.x in the VM.

Quick Start — Automated Demo (Dockerized)

This brings up the server and two scripted clients (“Alice” and “Bob”) that exchange messages and exit.

PowerShell

cd .\dockerized_version
docker compose down -v --remove-orphans
docker compose up --build

Expected: the server announces readiness, both clients connect, exchange the scripted lines, and exit with code 0. Stop with Ctrl+C.

Git Bash / WSL

cd dockerized_version
docker compose down -v --remove-orphans
docker compose up --build

Interactive (Individualized) Clients — Dockerized

Run the server once, then attach two separate interactive clients (each in its own terminal).

PowerShell

Terminal 1 — Server (detached):

cd .\dockerized_version
docker compose up --build -d server

Terminal 2 — Client #1 (interactive):

cd .\dockerized_version
docker compose run --rm -it --name alice client1_demo python chat_client.py --server server --port 12000

Terminal 3 — Client #2 (interactive):

cd .\dockerized_version
docker compose run --rm -it --name bob client2_demo python chat_client.py --server server --port 12000

Type a username when prompted, then chat. Type bye to leave.

Shutdown:

docker compose down -v

Git Bash / WSL

Terminal 1 — Server (detached):

cd dockerized_version
docker compose up --build -d server

Terminal 2 — Client #1:

cd dockerized_version
docker compose run --rm -it --name alice client1_demo python chat_client.py --server server --port 12000

Terminal 3 — Client #2:

cd dockerized_version
docker compose run --rm -it --name bob client2_demo python chat_client.py --server server --port 12000

Shutdown:

docker compose down -v

Optional: tmux Split-Pane Runner (Git Bash / WSL)

The tmux_interactive.sh helper opens a tmux session with panes for the server and two clients.

cd dockerized_version
chmod +x tmux_interactive.sh
./tmux_interactive.sh

Requirements: tmux available in your shell (sudo apt-get install tmux in WSL/Ubuntu). Close panes or press Ctrl+b then : and type kill-session to exit.

Oracle VirtualBox — Mininet Walkthrough

Run the server and two clients on three separate hosts inside the Mininet VM.

1) Start a 3-host topology

In the Mininet VM:

sudo mn --topo single,3 --mac

You’ll enter the mininet> CLI with hosts h1, h2, h3.

2) Open terminals for each host (xterm)

If you have X forwarding configured:

mininet> xterm h1 h2 h3

Alternatively, run commands inline by prefixing with the host name (shown below).

3) Place the app files on the VM

Copy chat_server.py and chat_client.py from oracle_vm_mininet_version/ into the VM (e.g., via shared folders or scp). Assume they are in /home/mininet/chat/.

4) Run the server and clients

Server on h1:

mininet> h1 python3 /home/mininet/chat/chat_server.py

Client on h2:

mininet> h2 python3 /home/mininet/chat/chat_client.py

Client on h3:

mininet> h3 python3 /home/mininet/chat/chat_client.py

Enter usernames and chat between h2 and h3. Type bye from a client to leave; the server stays up to serve subsequent sessions (if your server variant is configured to remain running).

Stop Mininet:

mininet> exit
sudo mn -c

Troubleshooting

• Server marked unhealthy in Compose: ensure the healthcheck in docker-compose.yml uses a valid command (e.g., a small Python socket connect to 127.0.0.1:12000) and that the server is listening before clients start.
• ConnectionRefusedError from a client: the client started before the server was ready. Use depends_on: condition: service_healthy for demo clients, or start the server first for interactive runs.
• Windows line endings: scripts expect LF line endings. If you see odd behavior, convert with dos2unix.