wse-server 1.4.1

Rust-powered WebSocket engine for Python. Up to 14M msg/s JSON, 30M binary (MsgPack/zlib). Zero-GIL JWT. E2E encrypted.

WSE -- WebSocket Engine

A complete, out-of-the-box solution for real-time communication between React, Python, and backend services.

Three packages. Four lines of code. Your frontend and backend talk in real time.

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Why WSE?

Building real-time features between React and Python is painful. You need WebSocket handling, reconnection logic, message ordering, authentication, encryption, offline support, health monitoring. That's weeks of work before you ship a single feature.

WSE gives you all of this out of the box.

Install wse-server on your backend, wse-client on your frontend (React or Python). Everything works immediately: auto-reconnection, message encryption, sequence ordering, offline queues, health monitoring. No configuration required for the defaults. Override what you need.

The engine is Rust-accelerated via PyO3. 14M msg/s JSON, 30M msg/s binary, 2.1M deliveries/s fan-out, 500K concurrent connections with zero message loss -- benchmarked on AMD EPYC 7502P. Multi-instance horizontal scaling via Redis pub/sub. Sub-millisecond latency (0.38 ms) with Rust JWT authentication.

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Quick Start

Server (Python) -- Router Mode

Embed WSE into your existing FastAPI app on the same port:

from fastapi import FastAPI
from wse_server import create_wse_router, WSEConfig

app = FastAPI()

wse = create_wse_router(WSEConfig(
    redis_url="redis://localhost:6379",
))

app.include_router(wse, prefix="/wse")

# Publish from anywhere in your app
await wse.publish("notifications", {"text": "Order shipped!", "order_id": 42})

Server (Python) -- Standalone Mode

Run the Rust WebSocket server on a dedicated port for maximum throughput:

from wse_server._wse_accel import RustWSEServer

server = RustWSEServer(
    "0.0.0.0", 5006,
    max_connections=10000,
    jwt_secret=b"your-secret-key",     # Rust JWT validation in handshake
    jwt_issuer="your-app",
    jwt_audience="your-api",
)
server.start()

# Drain inbound events in a background thread
while True:
    events = server.drain_inbound(256, 50)  # batch size, timeout ms
    for event in events:
        handle(event)

Standalone mode gives you a dedicated Rust tokio runtime on its own port -- no FastAPI overhead, no GIL on the hot path. This is how WSE achieves 14M msg/s on JSON.

Client (React)

import { useWSE } from 'wse-client';

function Dashboard() {
  const { isConnected, connectionHealth } = useWSE({
    topics: ['notifications', 'live_data'],
    endpoints: ['ws://localhost:8000/wse'],
  });

  useEffect(() => {
    const handler = (e: CustomEvent) => {
      console.log('New notification:', e.detail);
    };
    window.addEventListener('notifications', handler);
    return () => window.removeEventListener('notifications', handler);
  }, []);

  return <div>Status: {connectionHealth}</div>;
}

That's it. Your React app receives real-time updates from your Python backend.

Client (Python)

from wse_client import connect

async with connect("ws://localhost:5006/wse", token="your-jwt") as client:
    await client.subscribe(["notifications", "live_data"])
    async for event in client:
        print(event.type, event.payload)

Same wire protocol, same features. Use the Python client for backend-to-backend communication, microservices, CLI tools, integration tests, or any non-browser use case.

---

What You Get Out of the Box

Everything listed below works the moment you install. No extra setup.

Reactive Interface

Real-time data flow from Python to React. One hook (useWSE) on the client, one publish() call on the server. Events appear in your components instantly.

Auto-Reconnection

Exponential backoff with jitter. Connection drops? The client reconnects automatically. No lost messages -- offline queue with IndexedDB persistence stores messages while disconnected and replays them on reconnect.

End-to-End Encryption

ECDH P-256 key exchange with AES-GCM-256 per connection. Each connection negotiates a unique session key during the handshake (server_ready / client_hello), then all sensitive messages are encrypted end-to-end. HMAC-SHA256 message signing for integrity. Pluggable encryption and token providers via Python protocols.

Message Ordering

Sequence numbers with gap detection and reordering buffer. Messages arrive in order even under high load or network instability. Out-of-order messages are buffered and delivered once the gap fills.

Authentication

JWT-based with HS256, validated in Rust during the WebSocket handshake (zero GIL, 0.01ms decode). Per-connection, per-topic access control. Cookie-based token extraction for seamless browser auth. Fallback to Python auth handler when Rust JWT is not configured.

Health Monitoring

Connection quality scoring (excellent / good / fair / poor), latency tracking, jitter analysis, packet loss detection. Your UI knows when the connection is degraded and can react accordingly.

Scaling

Redis pub/sub for multi-instance fan-out. Run N server instances behind a load balancer -- publish on any instance, all subscribers receive the message regardless of which instance they're connected to. Pipelined PUBLISH (up to 64 per round-trip), circuit breaker, exponential backoff with jitter, dead letter queue for failed messages. Capacity scales linearly with instances: tested up to 1.04M deliveries/s per instance.

Rust Performance

Compression, sequencing, filtering, rate limiting, and the WebSocket server itself are implemented in Rust via PyO3. Python API stays the same. Rust accelerates transparently.

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Full Feature List

Server (Python + Rust)

Feature	Description
Drain Mode	Batch-polling inbound events from Rust. One GIL acquisition per batch (up to 256 messages) instead of per-message Python callbacks. Condvar-based wakeup for zero busy-wait.
Write Coalescing	Outbound pipeline: feed() + batch try_recv() + single flush(). Reduces syscalls under load by coalescing multiple messages into one write.
Ping/Pong in Rust	Heartbeat handled entirely in Rust with zero Python round-trips. Configurable intervals. TCP_NODELAY on accept for minimal latency.
5-Level Priority Queue	CRITICAL(10), HIGH(8), NORMAL(5), LOW(3), BACKGROUND(1). Smart dropping under backpressure: lower-priority messages are dropped first. Batch dequeue ordered by priority.
Dead Letter Queue	Redis-backed DLQ for failed messages. 7-day TTL, 1000-message cap per channel. Manual replay via replay_dlq_message(). Prometheus metrics for DLQ size and replay count.
MongoDB-like Filters	14 operators: $eq, $ne, $gt, $lt, $gte, $lte, $in, $nin, $regex, $exists, $contains, $startswith, $endswith. Logical: $and, $or. Dot-notation for nested fields (payload.price). Compiled regex cache.
Event Sequencer	Monotonic sequence numbers with AHashSet dedup. Size-based and age-based eviction. Gap detection on both server and client.
Compression	Flate2 zlib with configurable levels (1-9). Adaptive threshold -- only compress when payload exceeds size limit. Binary mode via msgpack (rmp-serde) for 30% smaller payloads.
Rate Limiter	Atomic token-bucket rate limiter in Rust. Per-connection rate enforcement. 100K tokens capacity, 10K tokens/sec refill.
Message Deduplication	AHashSet-backed dedup with bounded queue. Prevents duplicate delivery across reconnections and Redis fan-out.
Wire Envelope	Protocol v1: {t, id, ts, seq, p, v}. Generic payload extraction with automatic type conversion (UUID, datetime, Enum, bytes to JSON-safe primitives). Latency tracking (latency_ms field).
Snapshot Provider	Protocol for initial state delivery. Implement get_snapshot(user_id, topics) and clients receive current state immediately on subscribe -- no waiting for the next publish cycle.
Circuit Breaker	Three-state machine (CLOSED / OPEN / HALF_OPEN). Sliding-window failure tracking. Automatic recovery probes. Prevents cascade failures when downstream services are unhealthy.
Message Categories	S (snapshot), U (update), WSE (system). Category prefixing for client-side routing and filtering.
Multi-Instance Orchestration	Horizontal scaling via Redis pub/sub. Publish on any instance, all subscribers receive the message. Pipelined PUBLISH (64 commands/batch, 3 retries), circuit breaker (10-fail threshold, 60s reset), exponential backoff with jitter, dead letter queue (1000-entry ring buffer). 1.04M deliveries/s per instance, linear scaling with N instances.
PubSub Bus	Redis pub/sub with PSUBSCRIBE pattern matching. Glob wildcard topic routing (user:*:events). orjson fast-path serialization. Non-blocking handler invocation.
Pluggable Security	EncryptionProvider and TokenProvider protocols. Built-in: AES-GCM-256 with ECDH P-256 key exchange, HMAC-SHA256 signing, selective message signing. Rust-accelerated crypto (SHA-256, HMAC, AES-GCM, ECDH).
Rust JWT Authentication	HS256 JWT validation in Rust during the WebSocket handshake. Zero GIL acquisition on the connection critical path. 0.01ms decode (85x faster than Python). Cookie extraction and server_ready sent from Rust before Python runs.
Lock-Free Server Queries	get_connection_count() uses AtomicUsize — zero GIL, zero blocking, safe to call from async Python handlers. No channel round-trip to the tokio runtime.
Inbound MsgPack	Binary frames from msgpack clients are parsed in Rust via rmpv. Python receives pre-parsed dicts regardless of wire format. Zero Python overhead for msgpack connections.
Connection Metrics	Prometheus-compatible stubs for: messages sent/received, publish latency, DLQ size, handler errors, circuit breaker state. Drop-in Prometheus integration or use the built-in stubs.

Client (React + TypeScript)

Feature	Description
useWSE Hook	Single React hook for the entire WebSocket lifecycle. Accepts topics, endpoints, auth tokens. Returns isConnected, connectionHealth, connection controls.
Connection Pool	Multi-endpoint support with health-scored failover. Three load-balancing strategies: weighted-random, least-connections, round-robin. Automatic health checks with latency tracking.
Adaptive Quality Manager	Adjusts React Query defaults based on connection quality. Excellent: staleTime: Infinity (pure WebSocket). Poor: aggressive polling fallback. Dispatches wse:quality-change events. Optional QueryClient integration.
Offline Queue	IndexedDB-backed persistent queue. Messages are stored when disconnected and replayed on reconnect, ordered by priority. Configurable max size and TTL.
Network Monitor	Real-time latency, jitter, and packet-loss analysis. Determines connection quality (excellent / good / fair / poor). Generates diagnostic suggestions.
Event Sequencer	Client-side sequence validation with gap detection. Out-of-order buffer for reordering. Duplicate detection via seen-ID window with age-based eviction.
Circuit Breaker	Client-side circuit breaker for connection attempts. Prevents reconnection storms when the server is down. Configurable failure threshold and recovery timeout.
Compression + msgpack	Client-side decompression (pako zlib) and msgpack decoding. Automatic detection of binary vs JSON frames.
Zustand Stores	useWSEStore for connection state, latency history, diagnostics. useMessageQueueStore for message buffering with priority. Lightweight, no boilerplate.
Rate Limiter	Client-side token-bucket rate limiter for outbound messages. Prevents flooding the server.
Security Manager	Client-side HMAC verification and optional decryption. Validates message integrity before dispatching to handlers.

Client (Python)

Feature	Description
Async + Sync API	AsyncWSEClient with async context manager and async iterator. SyncWSEClient wrapper for threaded/synchronous code.
Connection Manager	Auto-reconnection with 4 strategies (exponential, linear, fibonacci, adaptive). Jitter, configurable max attempts. Heartbeat with PING/PONG.
Connection Pool	Multi-endpoint support with health scoring. Weighted-random, least-connections, round-robin load balancing.
Circuit Breaker	Three-state machine (CLOSED / OPEN / HALF_OPEN). Prevents reconnection storms.
Rate Limiter	Client-side token-bucket rate limiter for outbound messages.
Event Sequencer	Duplicate detection (10K ID window) and out-of-order reordering buffer.
Network Monitor	Latency, jitter, packet loss analysis. Connection quality scoring.
Security	ECDH P-256 key exchange, AES-GCM-256 encryption, HMAC-SHA256 signing. Wire-compatible with server and TypeScript client.
Compression + msgpack	Zlib decompression and msgpack decoding. Automatic binary frame detection.

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Performance

Rust-accelerated engine via PyO3. AMD EPYC 7502P (32 cores, 128 GB), Ubuntu 24.04, localhost.

Highlights

Metric	Value	Details
Peak throughput	14.2M msg/s	JSON, Rust client, 500 connections
Peak binary	30M msg/s	MsgPack/compressed, Rust client
Fan-out broadcast	2.1M deliveries/s	Single-instance, zero message loss
Max connections	500,000	Zero errors, zero gaps at every tier
Connection latency	0.38 ms median	Rust JWT auth in handshake
Accept rate	15,020 conn/s	Sustained connection establishment
Memory per conn	4.4 KB	Rust core static overhead

Point-to-Point (Rust Native Client)

Payload	Throughput	Bandwidth
64 bytes	19.4M msg/s	1.2 GB/s
256 bytes	12.5M msg/s	3.1 GB/s
1 KB	10.3M msg/s	10.0 GB/s
16 KB	1.2M msg/s	19.9 GB/s
64 KB	284K msg/s	18.2 GB/s

Point-to-Point (Python Multi-Process, 64 Workers)

Metric	JSON	MsgPack
Sustained	2,045,000 msg/s	2,072,000 msg/s
Burst	1,557,000 msg/s	1,836,000 msg/s
64KB messages	256K msg/s (16.0 GB/s)	--
Ping RTT	0.26 ms median	--

Point-to-Point (TypeScript/Node.js, 64 Processes)

Format	Throughput	Scaling
JSON	7.0M msg/s	97% linear
MsgPack	7.9M msg/s	+13% over JSON

Fan-out Broadcast (Single-Instance)

Server broadcasts to N subscribers. Zero message loss at every tier.

Subscribers	Deliveries/s	Bandwidth	p50 Latency
10	2.1M	295 MB/s	0.005 ms
1,000	1.4M	185 MB/s	--
10,000	1.2M	163 MB/s	--
100,000	1.7M	234 MB/s	--
500,000	1.4M	128 MB/s	--

Rust Acceleration vs Python

Component	Speedup	Rust	Python
JWT decode (HS256)	85x	10 us	850 us
Msgpack parsing	~50x	--	--
Rate limiter	40x	--	--
HMAC-SHA256	22x	--	--
Compression (zlib)	6.7x	--	--

See benchmark docs for full results: Overview | Rust Client | TypeScript Client | Python Client | Fan-out

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Use Cases

WSE works for any real-time communication between frontend and backend:

• Live dashboards -- stock prices, sensor data, analytics, monitoring panels
• Notifications -- order updates, alerts, system events pushed to the browser
• Collaborative apps -- shared cursors, document editing, whiteboarding
• Chat and messaging -- group chats, DMs, typing indicators, read receipts
• IoT and telemetry -- device status, real-time metrics, command and control
• Gaming -- game state sync, leaderboards, matchmaking updates

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Installation

# Server (Python) -- includes prebuilt Rust engine
pip install wse-server

# Client (React/TypeScript)
npm install wse-client

# Client (Python) -- pure Python, no Rust required
pip install wse-client

Server: prebuilt wheels for Linux (x86_64, aarch64), macOS (Intel, Apple Silicon), and Windows. Python 3.12+ (ABI3 stable -- one wheel per platform).

Python client: pure Python, Python 3.11+. Optional extras: pip install wse-client[crypto] for encryption, pip install wse-client[all] for everything.

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Architecture

React Client (TypeScript)       Python Client              Server (Python + Rust)
========================        ========================   ========================

useWSE hook                     AsyncWSEClient             FastAPI Router (/wse)
    |                               |                        -- OR --
    v                               v                      RustWSEServer (:5006)
ConnectionPool                  ConnectionPool                  |
    |  (multi-endpoint,             |  (multi-endpoint,         v
    |   health scoring)             |   health scoring)   Rust Engine (PyO3)
    v                               v                          |
ConnectionManager               ConnectionManager              v
    |  (auto-reconnect,             |  (auto-reconnect,   EventTransformer
    |   circuit breaker)            |   circuit breaker)       |
    v                               v                          v
MessageProcessor                MessageCodec              PriorityQueue
    |  (decompress, verify,         |  (decompress,            |
    |   sequence, dispatch)         |   sequence, dedup)       v
    v                               v                     Sequencer + Dedup
AdaptiveQualityManager          NetworkMonitor                 |
    |                               |  (quality scoring,       v
    v                               |   latency, jitter)  Compression + Rate Limiter
Zustand Store                       v                          |
    |                           Event handlers /               v
    v                           async iterator            PubSub Bus (Redis)
React Components                                               |
                                                               v
                                                          Dead Letter Queue

Wire format (v1):

{
  "v": 1,
  "id": "019503a1-...",
  "t": "price_update",
  "ts": "2026-01-15T10:30:00Z",
  "seq": 42,
  "p": { "symbol": "AAPL", "price": 187.42 }
}

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Packages

Package	Registry	Language	Install
wse-server	PyPI	Python + Rust	pip install wse-server
wse-client	npm	TypeScript + React	npm install wse-client
wse-client	PyPI	Python	pip install wse-client

All packages are standalone. No shared dependencies between server and clients.

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Documentation

Document	Description
Protocol Spec	Wire format, versioning, encryption
Architecture	System design, data flow
Benchmarks	Methodology, results, comparisons
Security Model	Encryption, auth, threat model
Integration Guide	FastAPI setup, Redis, deployment

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Technology Stack

Component	Technology	Purpose
Rust engine	PyO3 + maturin	Compression, sequencing, filtering, rate limiting, WebSocket server
Server framework	FastAPI + Starlette	ASGI WebSocket handling
Serialization	orjson (Rust)	Zero-copy JSON
Binary protocol	msgpack (rmp-serde)	30% smaller payloads
Encryption	AES-GCM-256 + ECDH P-256 (Rust)	Per-connection E2E encryption with key exchange
Message signing	HMAC-SHA256 (Rust)	Per-message integrity verification
Authentication	Rust JWT (HS256)	Zero-GIL token validation in handshake
Pub/Sub backbone	Redis Pub/Sub	Multi-process fan-out
Dead Letter Queue	Redis Lists	Failed message recovery
Client state	Zustand	Lightweight React store
Client hooks	React 18+	useWSE hook with TypeScript
Offline storage	IndexedDB	Persistent offline queue
Python client	websockets + cryptography	Async/sync WebSocket client
Build system	maturin	Rust+Python hybrid wheels

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License

MIT