sessionbus 0.1.1

Session bus Python package

sessionbus

sessionbus is a lightweight WebSocket message bus for Python. Clients subscribe by (user_id, session_id); the server pushes payloads to all subscribers for that key. When disconnects, subscriber messages go into an outbox (in-memory or PostgreSQL) and are delivered when a client reconnects.

Key features

• Simple subscription model: One key per conversation: (user_id, session_id). Subscribe, send, and receive on that key.
• Outbox when offline: If no client is connected for a key, payloads are queued (memory + optional Postgres). On the next subscribe, the server drains the outbox and sends them.
• Connection pool (client): Client uses a pool of WebSockets; hash-based routing spreads keys across connections. Reconnect and re-subscribe are handled per slot.

Installation

From the project root

pip install -e .

With dev dependencies (pytest, pytest-asyncio, pytest-cov). See [project.optional-dependencies] in pyproject.toml:

pip install -e ".[dev]"

Optional: Postgres outbox backend:

pip install -e ".[postgres]"

Usage

Server: start the bus and push to a key:

from sessionbus import Server

server = Server(host="127.0.0.1", port=8765)
await server.start()

# Later: push to all subscribers of (user_id, session_id)
await server.push("user-1", "session-abc", payload)

For a runnable server script, see examples/run_server.py.

Client: connect, subscribe to the keys you need, then send and receive:

from sessionbus import Client

client = Client("ws://127.0.0.1:8765", pool_size=4)
await client.connect()
await client.subscribe("user-1", "session-abc")

await client.send("Hello", user_id="user-1", session_id="session-abc")
payload = await client.recv("user-1", "session-abc", timeout=5.0)

Development

Run tests:

pytest

License

sessionbus is released under the MIT License.