JavaScript SDK for Azure Web PubSub

Azure Web PubSub service is an Azure-managed service that helps developers easily build web applications with real-time features and publish-subscribe pattern. Any scenario that requires real-time publish-subscribe messaging between server and clients or among clients can use Azure Web PubSub service. Traditional real-time features that often require polling from server or submitting HTTP requests can also use Azure Web PubSub service.

There are two libraries offered for JavaScript: the service client library and express middleware. The following sections contain more information about these libraries.

• Service client library
• Express middleware

You can use this library in your app server side to manage the WebSocket client connections, as shown in below diagram:

• Send messages to hubs and groups.
• Send messages to particular users and connections.
• Organize users and connections into groups.
• Close connections
• Grant, revoke, and check permissions for an existing connection

Source code | Package (NPM) | Product documentation | Samples

• LTS versions of Node.js

• An Azure trial subscription.
• An existing Azure Web PubSub service instance.

npm install @azure/web-pubsub

const { WebPubSubServiceClient } = require("@azure/web-pubsub");

const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");

You can also authenticate the WebPubSubServiceClient using an endpoint and an AzureKeyCredential:

const { WebPubSubServiceClient, AzureKeyCredential } = require("@azure/web-pubsub");

const key = new AzureKeyCredential("<Key>");
const serviceClient = new WebPubSubServiceClient("<Endpoint>", key, "<hubName>");

Or authenticate the WebPubSubServiceClient using Microsoft Entra ID

1. Install the @azure/identity dependency

npm install @azure/identity

1. Update the source code to use DefaultAzureCredential:

const { WebPubSubServiceClient, AzureKeyCredential } = require("@azure/web-pubsub");

const key = new DefaultAzureCredential();
const serviceClient = new WebPubSubServiceClient("<Endpoint>", key, "<hubName>");

const { WebPubSubServiceClient } = require("@azure/web-pubsub");

const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");

// Get the access token for the WebSocket client connection to use
let token = await serviceClient.getClientAccessToken();

// Or get the access token and assign the client a userId
token = await serviceClient.getClientAccessToken({ userId: "user1" });

// return the token to the WebSocket client

const { WebPubSubServiceClient } = require("@azure/web-pubsub");

const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");

// Send a JSON message
await serviceClient.sendToAll({ message: "Hello world!" });

// Send a plain text message
await serviceClient.sendToAll("Hi there!", { contentType: "text/plain" });

// Send a binary message
const payload = new Uint8Array(10);
await serviceClient.sendToAll(payload.buffer);

const { WebPubSubServiceClient } = require("@azure/web-pubsub");

const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");

const groupClient = serviceClient.group("<groupName>");

// Add user to the group
await groupClient.addUser("user1");

// Send a JSON message
await groupClient.sendToAll({ message: "Hello world!" });

// Send a plain text message
await groupClient.sendToAll("Hi there!", { contentType: "text/plain" });

// Send a binary message
const payload = new Uint8Array(10);
await groupClient.sendToAll(payload.buffer);

const { WebPubSubServiceClient } = require("@azure/web-pubsub");

const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");

// Send a JSON message
await serviceClient.sendToUser("user1", { message: "Hello world!" });

// Send a plain text message
await serviceClient.sendToUser("user1", "Hi there!", { contentType: "text/plain" });

// Send a binary message
const payload = new Uint8Array(10);
await serviceClient.sendToUser("user1", payload.buffer);

const { WebPubSubServiceClient } = require("@azure/web-pubsub");
const WebSocket = require("ws");

const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");

const groupClient = serviceClient.group("<groupName>");

// close all the connections in the group
await groupClient.closeAllConnections({ reason: "<closeReason>" });

// check if the group has any connections
const hasConnections = await serviceClient.groupExists("<groupName>");

const { WebPubSubServiceClient } = require("@azure/web-pubsub");

function onResponse(rawResponse: FullOperationResponse): void {
  console.log(rawResponse);
}
const serviceClient = new WebPubSubServiceClient("<ConnectionString>", "<hubName>");
await serviceClient.sendToAll({ message: "Hello world!" }, { onResponse });

You can set the following environment variable to get the debug logs when using this library.

• Getting debug logs from the Azure Web PubSub client library

export AZURE_LOG_LEVEL=verbose

For more detailed instructions on how to enable logs, you can look at the @azure/logger package docs.

Use Live Trace from the Web PubSub service portal to view the live traffic.

When a WebSocket connection connects, the Web PubSub service transforms the connection lifecycle and messages into events in CloudEvents format. This library provides an express middleware to handle events representing the WebSocket connection's lifecycle and messages, as shown in below diagram:

Source code | Package (NPM) | API reference documentation | Product documentation | Samples

• LTS versions of Node.js
• Express version 4.x.x or higher

• An Azure trial subscription.
• An existing Azure Web PubSub endpoint.

npm install @azure/web-pubsub-express

const express = require("express");

const { WebPubSubEventHandler } = require("@azure/web-pubsub-express");
const handler = new WebPubSubEventHandler("chat");

const app = express();

app.use(handler.getMiddleware());

app.listen(3000, () =>
  console.log(`Azure WebPubSub Upstream ready at http://localhost:3000${handler.path}`)
);

const express = require("express");

const { WebPubSubEventHandler } = require("@azure/web-pubsub-express");
const handler = new WebPubSubEventHandler("chat", {
  handleConnect: (req, res) => {
    // auth the connection and set the userId of the connection
    res.success({
      userId: "<userId>"
    });
  },
  allowedEndpoints: ["https://<yourAllowedService>.webpubsub.azure.cn"]
});

const app = express();

app.use(handler.getMiddleware());

app.listen(3000, () =>
  console.log(`Azure WebPubSub Upstream ready at http://localhost:3000${handler.path}`)
);

const express = require("express");

const { WebPubSubEventHandler } = require("@azure/web-pubsub-express");
const handler = new WebPubSubEventHandler("chat", {
  allowedEndpoints: [
    "https://<yourAllowedService1>.webpubsub.azure.cn",
    "https://<yourAllowedService2>.webpubsub.azure.cn"
  ]
});

const app = express();

app.use(handler.getMiddleware());

app.listen(3000, () =>
  console.log(`Azure WebPubSub Upstream ready at http://localhost:3000${handler.path}`)
);

const express = require("express");

const { WebPubSubEventHandler } = require("@azure/web-pubsub-express");
const handler = new WebPubSubEventHandler("chat", {
  path: "customPath1"
});

const app = express();

app.use(handler.getMiddleware());

app.listen(3000, () =>
  // Azure WebPubSub Upstream ready at http://localhost:3000/customPath1
  console.log(`Azure WebPubSub Upstream ready at http://localhost:3000${handler.path}`)
);

const express = require("express");

const { WebPubSubEventHandler } = require("@azure/web-pubsub-express");

const handler = new WebPubSubEventHandler("chat", {
  handleConnect(req, res) {
    // You can set the state for the connection, it lasts throughout the lifetime of the connection
    res.setState("calledTime", 1);
    res.success();
  },
  handleUserEvent(req, res) {
    var calledTime = req.context.states.calledTime++;
    console.log(calledTime);
    // You can also set the state here
    res.setState("calledTime", calledTime);
    res.success();
  }
});

const app = express();

app.use(handler.getMiddleware());

app.listen(3000, () =>
  console.log(`Azure WebPubSub Upstream ready at http://localhost:3000${handler.path}`)
);

You can set the following environment variable to get the debug logs when using this library.

• Getting debug logs from the Azure Web PubSub client library

export AZURE_LOG_LEVEL=verbose

For more detailed instructions on how to enable logs, see @azure/logger package docs.

Use Live Trace from the Web PubSub service portal to view the live traffic.

Use these resources to start building your own application: