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How to Build an Air Messenger ASCII Client: Step‑by‑Step Guide

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How to Build an Air Messenger ASCII Client: Step‑by‑Step GuideThis guide walks you through building a simple Air Messenger ASCII client — a lightweight text-only chat application inspired by classic terminal messengers and ASCII art culture. It covers design decisions, technologies, network protocols, terminal UI, message formatting (including animated ASCII), and deployment. The goal is a clear, modular project you can extend: a server to route messages and multiple terminal clients that render ASCII-friendly chats and animations.

Project overview and goals

  • Primary goal: create a minimal, low-bandwidth chat system that works in text terminals and emphasizes ASCII rendering.
  • Components:
    • Server: manages user sessions, channels/rooms, message delivery, basic persistence (optional).
    • Client: terminal-based UI for sending/receiving messages, showing user list, rendering ASCII art and simple animations.
  • Constraints:
    • Plain-text only (no binary image transfer).
    • Low bandwidth and latency; support slow connections.
    • Cross-platform where possible (Linux/macOS/Windows terminals).
  • Technologies (suggested):
    • Server: Node.js with WebSocket (ws) or Python with asyncio + websockets.
    • Client: Python (curses or urwid) or Node.js (blessed or neo-blessed).
    • Message format: JSON over WebSocket or simple line-based protocol over TCP.
    • Optional: TLS for encrypted transport.

Design

Protocol and message format

Use JSON for simplicity and extensibility. Minimal message types:

  • join: { “type”:“join”, “user”:“nick”, “room”:“#room” }
  • leave: { “type”:“leave”, “user”:“nick”, “room”:“#room” }
  • msg: { “type”:“msg”, “from”:“nick”, “room”:“#room”, “text”:“…”,“ts”:1234567890 }
  • presence: { “type”:“presence”, “room”:“#room”, “users”:[“a”,“b”] }
  • ascii_art: { “type”:“ascii_art”, “from”:“nick”, “room”:“#room”, “lines”:[“…”,“…”], “width”:80, “height”:10 }
  • animate: { “type”:“animate”, “frames”:[[“line1”,“line2”], [“f2-1”,“f2-2”]], “fps”:4 }

Keep messages small — compress or chunk large ASCII art if needed.

Server responsibilities

  • Accept connections and authenticate (simple nickname or OAuth for production).
  • Maintain rooms and subscriptions.
  • Broadcast messages to subscribers.
  • Optionally persist recent messages per room for history.
  • Rate-limit and validate input to prevent abuse.

Step‑by‑Step Implementation (Python + websockets + curses)

Below is a high-level implementation plan with code snippets for a minimal working prototype. This example uses Python 3.10+, the websockets library for the server and client networking, and curses for terminal UI.

1) Server: simple WebSocket router

Install dependencies:

pip install websockets

server.py

import asyncio import json import websockets from collections import defaultdict ROOMS = defaultdict(set)  # room -> set of websockets NICK = {}  # websocket -> nick async def notify_room(room, message):     if ROOMS[room]:         await asyncio.wait([ws.send(message) for ws in ROOMS[room]]) async def handler(ws, path):     try:         async for raw in ws:             try:                 msg = json.loads(raw)             except:                 continue             t = msg.get("type")             if t == "join":                 nick = msg.get("user")                 room = msg.get("room")                 NICK[ws] = nick                 ROOMS[room].add(ws)                 # send presence update                 users = [NICK[s] for s in ROOMS[room] if s in NICK]                 await notify_room(room, json.dumps({"type":"presence","room":room,"users":users}))             elif t == "leave":                 room = msg.get("room")                 if ws in ROOMS[room]:                     ROOMS[room].remove(ws)             elif t in ("msg","ascii_art","animate"):                 room = msg.get("room")                 await notify_room(room, json.dumps(msg))     finally:         # cleanup         nick = NICK.pop(ws, None)         for room, sockets in list(ROOMS.items()):             if ws in sockets:                 sockets.remove(ws)                 users = [NICK[s] for s in sockets if s in NICK]                 asyncio.create_task(notify_room(room, json.dumps({"type":"presence","room":room,"users":users}))) async def main():     async with websockets.serve(handler, "0.0.0.0", 8765):         print("Server running on :8765")         await asyncio.Future() if __name__ == "__main__":     asyncio.run(main())

Notes:

  • This is intentionally minimal. Add authentication, TLS, persistence, and error handling for production.

2) Client: terminal UI with curses and websocket connection

Install:

pip install websockets blessed

client.py

import asyncio, json, time import websockets from blessed import Terminal from asyncio import Queue term = Terminal() async def ws_recv(ws, q:Queue):     async for raw in ws:         q.put_nowait(raw) def render_chat(lines, users, term, height, width):     print(term.clear())     # header     print(term.bold("Air Messenger ASCII — Room"))     print("-" * width)     # messages area     for ln in lines[-(height-6):]:         print(ln[:width])     print("-" * width)     print("Users: " + ", ".join(users))     print("> ", end="", flush=True) async def main():     nick = input("Nick: ")     room = input("Room: ")     uri = "ws://localhost:8765"     lines = []     users = []     q = Queue()     async with websockets.connect(uri) as ws:         await ws.send(json.dumps({"type":"join","user":nick,"room":room}))         recv_task = asyncio.create_task(ws_recv(ws, q))         with term.fullscreen():             while True:                 # render                 render_chat(lines, users, term, term.height, term.width)                 # non-blocking input                 msg = input()                 if msg.startswith("/ascii "):                     art = msg[len("/ascii "):].split("\n")                     payload = {"type":"ascii_art","from":nick,"room":room,"lines":art}                     await ws.send(json.dumps(payload))                 else:                     payload = {"type":"msg","from":nick,"room":room,"text":msg,"ts":time.time()}                     await ws.send(json.dumps(payload))                 # process incoming                 while not q.empty():                     raw = await q.get()                     msg = json.loads(raw)                     t = msg.get("type")                     if t == "msg":                         lines.append(f"[{msg.get('from')}] {msg.get('text')}")                     elif t == "ascii_art":                         lines.append(f"[{msg.get('from')}] (ASCII Art)")                         lines.extend(msg.get("lines", []))                     elif t == "presence":                         users = msg.get("users", [])

Notes:

  • This client uses blocking input for simplicity; a production client should use asynchronous input handling or separate threads to avoid input blocking the receive loop.
  • For better terminal control use curses or urwid. blessed is simpler for cross-platform support.

3) ASCII art and animation features

  • ASCII art messages: send as an array of lines. Clients render them monospaced and may crop to terminal width.
  • Animated ASCII: send a sequence of frames with fps. Clients play frames locally rather than streaming full frames from server each tick to reduce bandwidth — send frames and timing once.
  • Compression: for large frames, compress text (gzip/base64) or send diffs between frames.

Example animate payload:

{   "type":"animate",   "from":"alice",   "room":"#lobby",   "frames":[["frame1-line1","frame1-line2"],["frame2-line1","frame2-line2"]],   "fps":4 }

Client plays by iterating frames at given fps.

4) Rendering tips

  • Use monospaced fonts and respect terminal width; wrap long lines carefully.
  • Provide a toggle to view raw ASCII (no wrapping) vs wrapped.
  • Support scrolling: keep recent N lines visible and allow history navigation.
  • Use colors sparingly for usernames and message types; keep art monochrome for compatibility.
  • For accessibility: allow font size/contrast settings in terminal emulator.

5) Security and robustness

  • Use TLS (wss://) in production.
  • Sanitize inputs to prevent terminal escape sequences being injected (strip or escape ANSI control codes unless you intentionally support them).
  • Rate-limit message sizes and frequency.
  • Authenticate users if needed; map nicks to unique IDs.
  • Store logs only if necessary and with user consent.

6) Deployment and scaling

  • Single-server works for small groups. For larger scale:
    • Use Redis pub/sub for routing between workers.
    • Run multiple server instances behind a load balancer supporting sticky sessions or use a central message broker.
    • Persist recent messages in Redis or a lightweight DB for quick history on join.
  • Monitor connections and memory; control max room sizes.

Example extensions and ideas

  • Integrate an ASCII art editor in the client with live preview.
  • Add slash commands: /who, /me, /nick, /roll, /gif (fetch ASCII GIFs).
  • Bots that post ASCII weather, clocks, or games (e.g., tic-tac-toe rendered in ASCII).
  • Gateway to pretty-print images as ASCII via server-side conversion.

Conclusion

You now have a blueprint to build an Air Messenger ASCII client: a server to route JSON messages over WebSocket; a terminal client that renders plain text, ASCII art, and animations; and design choices for security, scaling, and UX. Start with the minimal server and client above, then iterate: add nonblocking input, sanitize input, add TLS, and expand features like editors and bots.

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