@azure/web-pubsub-client v1.0.1

Azure Web PubSub Client

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.

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

Details about the terms used here are described in Key concepts section.

API reference documentation | Product documentation | Samples

Getting started

Currently supported environments

• LTS versions of Node.js

Prerequisites

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

1. Install the @azure/web-pubsub-client package

npm install @azure/web-pubsub-client

2. Create a WebPubSubClient and copy client-access-url from Azure Portal

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

client = new WebPubSubClient("<<client-access-url>>");

await client.start();

Key concepts

Connection

A connection, also known as a client or a client connection, represents an individual WebSocket connection connected to the Web PubSub service. When successfully connected, a unique connection ID is assigned to this connection by the Web PubSub service.

Hub

A hub is a logical concept for a set of client connections. Usually you use one hub for one purpose, for example, a chat hub, or a notification hub. When a client connection is created, it connects to a hub, and during its lifetime, it belongs to that hub. Different applications can share one Azure Web PubSub service by using different hub names.

Group

A group is a subset of connections to the hub. You can add a client connection to a group, or remove the client connection from the group, anytime you want. For example, when a client joins a chat room, or when a client leaves the chat room, this chat room can be considered to be a group. A client can join multiple groups, and a group can contain multiple clients.

User

Connections to Web PubSub can belong to one user. A user might have multiple connections, for example when a single user is connected across multiple devices or multiple browser tabs.

Client Events

Events are created during the lifecycle of a client connection. For example, a simple WebSocket client connection creates a connect event when it tries to connect to the service, a connected event when it successfully connected to the service, a message event when it sends messages to the service and a disconnected event when it disconnects from the service.

Event Handler

Event handler contains the logic to handle the client events. Event handler needs to be registered and configured in the service through the portal or Azure CLI beforehand. The place to host the event handler logic is generally considered as the server-side.

Examples

Start a client

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

client = new WebPubSubClient("<<client-access-url>>");

await client.start();

Troubleshooting

Enable logs

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

• Getting debug logs from the SignalR 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.

Live Trace

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

Next steps

Please take a look at the samples directory for detailed examples on how to use this library.

Contributing

If you'd like to contribute to this library, please read the contributing guide to learn more about how to build and test the code.

Related projects

• Microsoft Azure SDK for Javascript