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Updating Websocket server example (#24333)
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‎src/content/docs/durable-objects/examples/websocket-server.mdx‎

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@@ -22,87 +22,113 @@ WebSocket connections pin your Durable Object to memory, and so duration charges
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<TypeScriptExample>
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```ts
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import { DurableObject } from "cloudflare:workers";
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export interface Env {
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WEBSOCKET_SERVER: DurableObjectNamespace<WebSocketServer>;
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}
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import { DurableObject } from 'cloudflare:workers';
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// Worker
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export default {
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async fetch(request, env, ctx): Promise<Response> {
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if (request.url.endsWith("/websocket")) {
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// Expect to receive a WebSocket Upgrade request.
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// If there is one, accept the request and return a WebSocket Response.
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const upgradeHeader = request.headers.get("Upgrade");
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if (!upgradeHeader || upgradeHeader !== "websocket") {
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return new Response("Durable Object expected Upgrade: websocket", {
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status: 426,
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});
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}
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// This example will refer to the same Durable Object,
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// since the name "foo" is hardcoded.
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let id = env.WEBSOCKET_SERVER.idFromName("foo");
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let stub = env.WEBSOCKET_SERVER.get(id);
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return stub.fetch(request);
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}
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return new Response(null, {
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status: 400,
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statusText: "Bad Request",
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headers: {
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"Content-Type": "text/plain",
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},
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});
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},
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} satisfies ExportedHandler<Env>;
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async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
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if (request.url.endsWith('/websocket')) {
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// Expect to receive a WebSocket Upgrade request.
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// If there is one, accept the request and return a WebSocket Response.
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const upgradeHeader = request.headers.get('Upgrade');
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if (!upgradeHeader || upgradeHeader !== 'websocket') {
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return new Response('Worker expected Upgrade: websocket', {
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status: 426,
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});
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}
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if (request.method !== 'GET') {
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return new Response('Worker expected GET method', {
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status: 400,
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});
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}
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// Since we are hard coding the Durable Object ID by providing the constant name 'foo',
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// all requests to this Worker will be sent to the same Durable Object instance.
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let id = env.WEBSOCKET_SERVER.idFromName('foo');
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let stub = env.WEBSOCKET_SERVER.get(id);
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return stub.fetch(request);
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}
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return new Response(
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`Supported endpoints:
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/websocket: Expects a WebSocket upgrade request`,
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{
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status: 200,
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headers: {
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'Content-Type': 'text/plain',
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},
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}
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);
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},
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};
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// Durable Object
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export class WebSocketServer extends DurableObject {
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currentlyConnectedWebSockets: number;
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constructor(ctx: DurableObjectState, env: Env) {
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// This is reset whenever the constructor runs because
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// regular WebSockets do not survive Durable Object resets.
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//
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// WebSockets accepted via the Hibernation API can survive
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// a certain type of eviction, but we will not cover that here.
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super(ctx, env);
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this.currentlyConnectedWebSockets = 0;
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}
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async fetch(request: Request): Promise<Response> {
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// Creates two ends of a WebSocket connection.
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const webSocketPair = new WebSocketPair();
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const [client, server] = Object.values(webSocketPair);
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// Calling `accept()` tells the runtime that this WebSocket is to begin terminating
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// request within the Durable Object. It has the effect of "accepting" the connection,
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// and allowing the WebSocket to send and receive messages.
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server.accept();
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this.currentlyConnectedWebSockets += 1;
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// Upon receiving a message from the client, the server replies with the same message,
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// and the total number of connections with the "[Durable Object]: " prefix
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server.addEventListener("message", (event: MessageEvent) => {
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server.send(
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`[Durable Object] currentlyConnectedWebSockets: ${this.currentlyConnectedWebSockets}`,
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);
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});
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// If the client closes the connection, the runtime will close the connection too.
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server.addEventListener("close", (cls: CloseEvent) => {
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this.currentlyConnectedWebSockets -= 1;
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server.close(cls.code, "Durable Object is closing WebSocket");
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});
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return new Response(null, {
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status: 101,
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webSocket: client,
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});
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}
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// Keeps track of all WebSocket connections
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sessions: Map<WebSocket, { [key: string]: string }>;
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constructor(ctx: DurableObjectState, env: Env) {
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super(ctx, env);
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this.sessions = new Map();
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}
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async fetch(request: Request): Promise<Response> {
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// Creates two ends of a WebSocket connection.
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const webSocketPair = new WebSocketPair();
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const [client, server] = Object.values(webSocketPair);
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// Calling `accept()` tells the runtime that this WebSocket is to begin terminating
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// request within the Durable Object. It has the effect of "accepting" the connection,
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// and allowing the WebSocket to send and receive messages.
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server.accept();
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// Generate a random UUID for the session.
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const id = crypto.randomUUID();
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// Add the WebSocket connection to the map of active sessions.
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this.sessions.set(server, { id });
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server.addEventListener('message', (event) => {
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this.handleWebSocketMessage(server, event.data);
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});
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// If the client closes the connection, the runtime will close the connection too.
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server.addEventListener('close', () => {
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this.handleConnectionClose(server);
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});
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return new Response(null, {
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status: 101,
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webSocket: client,
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});
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}
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async handleWebSocketMessage(ws: WebSocket, message: string | ArrayBuffer) {
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const connection = this.sessions.get(ws)!;
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// Reply back with the same message to the connection
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ws.send(`[Durable Object] message: ${message}, from: ${connection.id}`);
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// Broadcast the message to all the connections,
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// except the one that sent the message.
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this.sessions.forEach((k, session) => {
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if (session !== ws) {
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session.send(`[Durable Object] message: ${message}, from: ${connection.id}`);
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}
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});
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// Broadcast the message to all the connections,
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// including the one that sent the message.
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this.sessions.forEach((k, session) => {
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session.send(`[Durable Object] message: ${message}, from: ${connection.id}`);
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});
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}
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async handleConnectionClose(ws: WebSocket) {
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this.sessions.delete(ws);
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ws.close(1000, 'Durable Object is closing WebSocket');
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}
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}
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```
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</TypeScriptExample>

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