Azure Web PubSub SDKs for TypeScript
Real-time messaging with WebSocket connections and pub/sub patterns.
Installation
bash
# 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
bash
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
typescript
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
typescript
// Basic token
const token = await client.getClientAccessToken();
// token.url contains a bearer credential: return only to the authorized client, never log it.
// Token with user ID
const userToken = await client.getClientAccessToken({
userId: "user123",
});
// Token with permissions
const permToken = await client.getClientAccessToken({
userId: "user123",
roles: [
"webpubsub.joinLeaveGroup.chat-room",
"webpubsub.sendToGroup.chat-room", // specific group
],
groups: ["chat-room"], // auto-join on connect
expirationTimeInMinutes: 60,
});
Send Messages
typescript
// 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
typescript
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
typescript
// 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
typescript
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
typescript
// 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
typescript
// 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
typescript
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.general"],
});
},
// 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) => {
if (!req.user?.id) return res.status(401).end();
const token = await serviceClient.getClientAccessToken({
userId: req.user.id, // prerequisite: verified authenticated application session
});
res.json({ url: token.url });
});
app.listen(8080);
Key Types
typescript
// 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
When to Use
This skill is applicable to execute the workflow or actions described in the overview.
Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.
The negotiate example requires real application authentication middleware; fail closed if identity is absent. Resolve user/group membership from the trusted server session, authorize every requested group and issue only group-specific roles with short expiry. Never grant a wildcard role while claiming group-scoped permissions. Tokens/connection URLs are bearer secrets; protect them in responses/logs and do not treat a connected socket as authorization for all groups. Scope broadcasts/group changes to the user’s approved recipients and content.