Azure Web PubSub SDKs for TypeScript

Real-time messaging with WebSocket connections and pub/sub patterns.

Installation

Server-side management

npm install @azure/web-pubsub @azure/identity

Client-side real-time messaging

npm install @azure/web-pubsub-client

Express middleware for event handlers

npm install @azure/web-pubsub-express

Environment Variables

WEBPUBSUB_CONNECTION_STRING=Endpoint=https://<resource>.webpubsub.azure.com;AccessKey=<key>;Version=1.0; WEBPUBSUB_ENDPOINT=https://<resource>.webpubsub.azure.com

Server-Side: WebPubSubServiceClient

Authentication

import { WebPubSubServiceClient, AzureKeyCredential } from "@azure/web-pubsub"; import { DefaultAzureCredential } from "@azure/identity";

// Connection string const client = new WebPubSubServiceClient( process.env.WEBPUBSUB_CONNECTION_STRING!, "chat" // hub name );

// DefaultAzureCredential (recommended) const client2 = new WebPubSubServiceClient( process.env.WEBPUBSUB_ENDPOINT!, new DefaultAzureCredential(), "chat" );

// AzureKeyCredential const client3 = new WebPubSubServiceClient( process.env.WEBPUBSUB_ENDPOINT!, new AzureKeyCredential("<access-key>"), "chat" );

Generate Client Access Token

// Basic token const token = await client.getClientAccessToken(); console.log(token.url); // wss://...?access_token=...

// Token with user ID const userToken = await client.getClientAccessToken({ userId: "user123", });

// Token with permissions const permToken = await client.getClientAccessToken({ userId: "user123", roles: [ "webpubsub.joinLeaveGroup", "webpubsub.sendToGroup", "webpubsub.sendToGroup.chat-room", // specific group ], groups: ["chat-room"], // auto-join on connect expirationTimeInMinutes: 60, });

Send Messages

// Broadcast to all connections in hub await client.sendToAll({ message: "Hello everyone!" }); await client.sendToAll("Plain text", { contentType: "text/plain" });

// Send to specific user (all their connections) await client.sendToUser("user123", { message: "Hello!" });

// Send to specific connection await client.sendToConnection("connectionId", { data: "Direct message" });

// Send with filter (OData syntax) await client.sendToAll({ message: "Filtered" }, { filter: "userId ne 'admin'", });

Group Management

const group = client.group("chat-room");

// Add user/connection to group await group.addUser("user123"); await group.addConnection("connectionId");

// Remove from group await group.removeUser("user123");

// Send to group await group.sendToAll({ message: "Group message" });

// Close all connections in group await group.closeAllConnections({ reason: "Maintenance" });

Connection Management

// Check existence const userExists = await client.userExists("user123"); const connExists = await client.connectionExists("connectionId");

// Close connections await client.closeConnection("connectionId", { reason: "Kicked" }); await client.closeUserConnections("user123"); await client.closeAllConnections();

// Permissions await client.grantPermission("connectionId", "sendToGroup", { targetName: "chat" }); await client.revokePermission("connectionId", "sendToGroup", { targetName: "chat" });

Client-Side: WebPubSubClient

Connect

import { WebPubSubClient } from "@azure/web-pubsub-client";

// Direct URL const client = new WebPubSubClient("<client-access-url>");

// Dynamic URL from negotiate endpoint const client2 = new WebPubSubClient({ getClientAccessUrl: async () => { const response = await fetch("/negotiate"); const { url } = await response.json(); return url; }, });

// Register handlers BEFORE starting client.on("connected", (e) => { console.log(Connected: ${e.connectionId}); });

client.on("group-message", (e) => { console.log(${e.message.group}: ${e.message.data}); });

await client.start();

Send Messages

// Join group first await client.joinGroup("chat-room");

// Send to group await client.sendToGroup("chat-room", "Hello!", "text"); await client.sendToGroup("chat-room", { type: "message", content: "Hi" }, "json");

// Send options await client.sendToGroup("chat-room", "Hello", "text", { noEcho: true, // Don't echo back to sender fireAndForget: true, // Don't wait for ack });

// Send event to server await client.sendEvent("userAction", { action: "typing" }, "json");

Event Handlers

// Connection lifecycle client.on("connected", (e) => { console.log(Connected: ${e.connectionId}, User: ${e.userId}); });

client.on("disconnected", (e) => { console.log(Disconnected: ${e.message}); });

client.on("stopped", () => { console.log("Client stopped"); });

// Messages client.on("group-message", (e) => { console.log([${e.message.group}] ${e.message.fromUserId}: ${e.message.data}); });

client.on("server-message", (e) => { console.log(Server: ${e.message.data}); });

// Rejoin failure client.on("rejoin-group-failed", (e) => { console.log(Failed to rejoin ${e.group}: ${e.error}); });

Express Event Handler

import express from "express"; import { WebPubSubEventHandler } from "@azure/web-pubsub-express";

const app = express();

const handler = new WebPubSubEventHandler("chat", { path: "/api/webpubsub/hubs/chat/",

// Blocking: approve/reject connection handleConnect: (req, res) => { if (!req.claims?.sub) { res.fail(401, "Authentication required"); return; } res.success({ userId: req.claims.sub[0], groups: ["general"], roles: ["webpubsub.sendToGroup"], }); },

// Blocking: handle custom events handleUserEvent: (req, res) => { console.log(Event from ${req.context.userId}:, req.data); res.success(Received: ${req.data}, "text"); },

// Non-blocking onConnected: (req) => { console.log(Client connected: ${req.context.connectionId}); },

onDisconnected: (req) => { console.log(Client disconnected: ${req.context.connectionId}); }, });

app.use(handler.getMiddleware());

// Negotiate endpoint app.get("/negotiate", async (req, res) => { const token = await serviceClient.getClientAccessToken({ userId: req.user?.id, }); res.json({ url: token.url }); });

app.listen(8080);

Key Types

// Server import { WebPubSubServiceClient, WebPubSubGroup, GenerateClientTokenOptions, HubSendToAllOptions, } from "@azure/web-pubsub";

// Client import { WebPubSubClient, WebPubSubClientOptions, OnConnectedArgs, OnGroupDataMessageArgs, } from "@azure/web-pubsub-client";

// Express import { WebPubSubEventHandler, ConnectRequest, UserEventRequest, ConnectResponseHandler, } from "@azure/web-pubsub-express";

Best Practices

• Use Entra ID auth - DefaultAzureCredential for production

• Register handlers before start - Don't miss initial events

• Use groups for channels - Organize messages by topic/room

• Handle reconnection - Client auto-reconnects by default

• Validate in handleConnect - Reject unauthorized connections early

• Use noEcho - Prevent message echo back to sender when needed