WebTransport Protocol: Next-Generation Web Communication 2026

// Client initiates WebTransport session
const transport = new WebTransport("https://example.com/wt");

// Wait for connection
await transport.ready;

// Connection established over HTTP/3
console.log("WebTransport connected");

// Create bidirectional stream
const stream = transport.createBidirectionalStream();

// Send data over reliable stream
const writer = stream.writable.getWriter();
await writer.write(new Uint8Array([1, 2, 3]));

// Receive data
const reader = stream.readable.getReader();
const { value } = await reader.read();

// Send unreliable datagram
await transport.sendDatagram(new Uint8Array([4, 5, 6]));

package main

import (
    "crypto/tls"
    "fmt"
    "github.com/quic-go/quic-go"
    "github.com/quic-go/webtransport-go"
)

func main() {
    cert, _ := tls.LoadX509KeyPair("cert.pem", "key.pem")

    config := &quic.Config{
        MaxIdleTimeout:     30 * time.Second,
        MaxIncomingStreams: 100,
    }

    listener, _ := webtransport.Listen("udp", ":443", &tls.Config{
        Certificates: []tls.Certificate{cert},
    }, config)

    for {
        conn, _ := listener.Accept(context.Background())
        handleSession(conn)
    }
}

func handleSession(conn *webtransport.Session) {
    for {
        stream, err := conn.AcceptStream(context.Background())
        if err != nil {
            break
        }
        go handleStream(stream)
    }
}

import { WebTransportServer } from '@fails-components/webtransport';

const server = new WebTransportServer({
    port: 443,
    cert: '/path/to/cert.pem',
    key: '/path/to/key.pem',
});

server.on('session', (session) => {
    console.log('New WebTransport session');

    // Handle bidirectional streams
    for await (const stream of session.incomingBidirectionalStreams) {
        handleStream(stream);
    }

    // Handle datagrams
    session.datagrams.readable.on('data', (data) => {
        console.log('Datagram received:', data);
    });
});

server.listen();

# nginx.conf (experimental module required)
load_module modules/ngx_http_webtransport_module.so;

events {
    worker_connections 1024;
}

http {
    server {
        listen 443 quic reuseport;
        listen 443 ssl;

        ssl_certificate /etc/ssl/server.crt;
        ssl_certificate_key /etc/ssl/server.key;
        ssl_protocols TLSv1.3;

        # Enable WebTransport
        webtransport on;

        location /wt/ {
            # WebTransport endpoint
        }
    }
}

class WebTransportClient {
    constructor(url) {
        this.url = url;
        this.transport = null;
        this.connected = false;
    }

    async connect() {
        this.transport = new WebTransport(this.url);

        this.transport.closed.then((closeInfo) => {
            console.log('Connection closed:', closeInfo);
        });

        await this.transport.ready;
        this.connected = true;
        console.log('WebTransport connected');
    }

    // Reliable streams
    async sendReliable(data) {
        const stream = this.transport.createBidirectionalStream();
        const writer = stream.writable.getWriter();
        await writer.write(data);
        await writer.close();
    }

    async receiveReliable() {
        const stream = await this.transport.incomingBidirectionalStreams
            .getReader().read();

        const reader = stream.readable.getReader();
        while (true) {
            const { done, value } = await reader.read();
            if (done) break;
            console.log('Received:', value);
        }
    }

    // Unreliable datagrams
    async sendDatagram(data) {
        await this.transport.sendDatagram(data);
    }

    startDatagramListener() {
        const reader = this.transport.datagrams.readable.getReader();
        while (true) {
            const { done, value } = await reader.read();
            if (done) break;
            console.log('Datagram received:', value);
        }
    }
}

// Usage
const client = new WebTransportClient('https://example.com/wt');
await client.connect();

async function createTransport(url) {
    // Try WebTransport first
    if ('WebTransport' in window) {
        try {
            return new WebTransport(url);
        } catch (e) {
            console.warn('WebTransport failed, falling back to WebSocket');
        }
    }

    // Fallback to WebSocket
    return createWebSocketFallback(url);
}

function createWebSocketFallback(url) {
    const wsUrl = url.replace(/^https:/, 'wss:').replace('/wt/', '/ws/');
    return new WebSocket(wsUrl);
}

// Game client using WebTransport
class GameClient {
    constructor() {
        this.state = {
            players: new Map(),
            position: { x: 0, y: 0 }
        };
    }

    async init() {
        this.transport = new WebTransport('https://game.example.com/wt');
        await this.transport.ready;

        // Send position updates via unreliable datagrams at 30 Hz
        setInterval(() => this.sendPositionUpdate(), 33);

        // Receive authoritative game state via reliable stream
        this.receiveGameState();
    }

    sendPositionUpdate() {
        const update = encodePositionUpdate(this.state.position);
        this.transport.sendDatagram(update);
    }

    async receiveGameState() {
        const stream = await this.transport.incomingBidirectionalStreams
            .getReader().read();

        const reader = stream.readable.getReader();
        while (true) {
            const { done, value } = await reader.read();
            if (done) break;
            const state = decodeGameState(value);
            this.updateLocalState(state);
        }
    }
}

// Live stream client with separate audio/video/metadata streams
class StreamClient {
    constructor(url) {
        this.url = url;
    }

    async connect() {
        this.transport = new WebTransport(this.url);
        await this.transport.ready;

        // Separate streams for different content types
        this.videoStream = this.transport.createBidirectionalStream();
        this.audioStream = this.transport.createBidirectionalStream();
        this.metaStream = this.transport.createBidirectionalStream();

        this.startDecoders();
    }

    startDecoders() {
        this.pipeStream(this.videoStream.readable, videoDecoder);
        this.pipeStream(this.audioStream.readable, audioDecoder);
        this.pipeStream(this.metaStream.readable, metaDecoder);
    }

    pipeStream(readable, decoder) {
        const reader = readable.getReader();
        const transformer = new TransformStream({
            transform(chunk, controller) {
                controller.enqueue(decoder.decode(chunk));
            }
        });
        readable.pipeThrough(transformer);
    }
}

// IoT sensor data collection over datagrams
class SensorClient {
    constructor(serverUrl) {
        this.serverUrl = serverUrl;
    }

    async start(sensorInterval = 1000) {
        this.transport = new WebTransport(this.serverUrl);
        await this.transport.ready;

        // Send sensor readings unreliably — a dropped reading is not critical
        setInterval(async () => {
            const readings = await this.readSensors();
            const encoded = this.encodeReadings(readings);
            await this.transport.sendDatagram(encoded);
        }, sensorInterval);

        // Receive configuration updates reliably
        this.receiveConfig();
    }

    async readSensors() {
        return {
            temperature: await this.readTemperature(),
            humidity: await this.readHumidity(),
            pressure: await this.readPressure()
        };
    }

    async receiveConfig() {
        const stream = await this.transport.incomingBidirectionalStreams
            .getReader().read();

        const reader = stream.readable.getReader();
        while (true) {
            const { done, value } = await reader.read();
            if (done) break;
            this.applyConfig(value);
        }
    }
}

// Stream AI inference results to browser clients
class AIInferenceClient {
    constructor(modelEndpoint) {
        this.endpoint = modelEndpoint;
    }

    async startInference(input) {
        const transport = new WebTransport(this.endpoint);
        await transport.ready;

        // Send input over reliable stream
        const inputStream = transport.createBidirectionalStream();
        const writer = inputStream.writable.getWriter();
        await writer.write(encodeInput(input));

        // Receive intermediate predictions via unreliable datagrams
        const datagramReader = transport.datagrams.readable.getReader();
        while (true) {
            const { done, value } = await datagramReader.read();
            if (done) break;
            const partial = decodePartialResult(value);
            this.updatePreview(partial); // Real-time preview
        }
    }

    async receiveFinalResult() {
        const stream = await this.transport.incomingBidirectionalStreams
            .getReader().read();
        const reader = stream.readable.getReader();
        const { value } = await reader.read();
        return decodeFinalResult(value);
    }
}

// Reuse WebTransport connections across components
class ConnectionPool {
    constructor(url, poolSize = 5) {
        this.url = url;
        this.pool = [];
        this.available = [];

        for (let i = 0; i < poolSize; i++) {
            this.available.push(this.createConnection());
        }
    }

    async getConnection() {
        if (this.available.length > 0) {
            return this.available.pop();
        }
        return this.createConnection();
    }

    releaseConnection(conn) {
        if (conn.state === 'connected') {
            this.available.push(conn);
        }
    }

    async createConnection() {
        const transport = new WebTransport(this.url);
        await transport.ready;
        return transport;
    }
}

// Batch small messages for efficient stream usage
class BatchedSender {
    constructor(transport, batchSize = 10, intervalMs = 50) {
        this.transport = transport;
        this.batch = [];
        this.batchSize = batchSize;
        this.intervalMs = intervalMs;
    }

    send(data) {
        this.batch.push(data);
        if (this.batch.length >= this.batchSize) {
            this.flush();
        }
    }

    async flush() {
        if (this.batch.length === 0) return;

        const stream = this.transport.createBidirectionalStream();
        const writer = stream.writable.getWriter();

        for (const item of this.batch) {
            await writer.write(item);
        }

        await writer.close();
        this.batch = [];
    }

    startAutoFlush() {
        setInterval(() => this.flush(), this.intervalMs);
    }
}

// Choose appropriate transmission mode per message type
class AdaptiveTransport {
    constructor(transport) {
        this.transport = transport;
    }

    sendUpdate(type, data) {
        if (type === 'telemetry') {
            // Unreliable: high frequency, loss tolerant, latency critical
            return this.transport.sendDatagram(data);
        }

        if (type === 'command') {
            // Reliable: every command must arrive
            const stream = this.transport.createBidirectionalStream();
            const writer = stream.writable.getWriter();
            return writer.write(data);
        }

        if (type === 'file') {
            // Reliable with backpressure
            return this.sendFile(data);
        }
    }
}

# Server TLS configuration
ssl_protocols TLSv1.3;
ssl_ciphers TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256;
ssl_prefer_server_ciphers on;

// Server-side: Verify WebTransport origin
server.on('session', (session) => {
    const origin = session.origin;

    if (!isAllowedOrigin(origin)) {
        session.close({
            closeCode: 8,
            reason: 'Origin not allowed'
        });
        return;
    }

    handleSession(session);
});

// Client-side rate limiting for datagrams
class RateLimitedClient {
    constructor(transport) {
        this.transport = transport;
        this.lastSend = 0;
        this.minInterval = 10; // ms
    }

    async send(data) {
        const now = Date.now();
        const elapsed = now - this.lastSend;

        if (elapsed < this.minInterval) {
            await new Promise(r => setTimeout(r, this.minInterval - elapsed));
        }

        this.lastSend = Date.now();
        return this.transport.sendDatagram(data);
    }
}

// View WebTransport frames
// 1. Open chrome://inspect
// 2. Enable WebTransport debugging
// 3. Visit chrome://net-export

# Chrome command line for QUIC log capture
chrome --enable-logging --v=1 \
    --log-net-log=/path/to/netlog.json

# Server-side qlog capture (quic-go)
export QLOGDIR=/var/log/quic/

transport.closed.catch((error) => {
    console.error('WebTransport error:', error);
    // Implement reconnection
});

transport.datagrams.readable.getReader().cancel();