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7.9.5 • Public • Published

Azure Service Bus client library for JavaScript

Azure Service Bus is a highly-reliable cloud messaging service from Microsoft.

Use the client library @azure/service-bus in your application to

  • Send messages to an Azure Service Bus Queue or Topic
  • Receive messages from an Azure Service Bus Queue or Subscription
  • Create/Get/Delete/Update/List Queues/Topics/Subscriptions/Rules in an Azure Service Bus namespace.

Resources for @azure/service-bus version 7:

Key links:

NOTE: If you are using version 1.1.10 or lower and want to migrate to the latest version of this package please look at our migration guide to move from Service Bus V1 to Service Bus V7

Getting started

Install the package

Install the latest version for the Azure Service Bus client library using npm.

npm install @azure/service-bus

Currently supported environments


Configure TypeScript

TypeScript users need to have Node type definitions installed:

npm install @types/node

You also need to enable compilerOptions.allowSyntheticDefaultImports in your tsconfig.json. Note that if you have enabled compilerOptions.esModuleInterop, allowSyntheticDefaultImports is enabled by default. See TypeScript's compiler options handbook for more information.

JavaScript Bundle

To use this client library in the browser, first you need to use a bundler. For details on how to do this, please refer to our bundling documentation.

In addition to what is described there, this library also needs additional polyfills for the following NodeJS core built-in modules in order to work properly in the browsers:

  • buffer
  • os
  • path
  • process

Bundling with Webpack

If you are using Webpack v5, you can install the following dev dependencies

  • npm install --save-dev os-browserify path-browserify

then add the following into your webpack.config.js

 const path = require("path");
+const webpack = require("webpack");

 module.exports = {
   entry: "./src/index.ts",
@@ -12,8 +13,21 @@ module.exports = {
+  plugins: [
+    new webpack.ProvidePlugin({
+      process: "process/browser",
+    }),
+    new webpack.ProvidePlugin({
+      Buffer: ["buffer", "Buffer"],
+    }),
+  ],
   resolve: {
     extensions: [".ts", ".js"],
+    fallback: {
+      buffer: require.resolve("buffer/"),
+      os: require.resolve("os-browserify"),
+      path: require.resolve("path-browserify"),
+    },

Bundling with Rollup

If you are using Rollup bundler, install the following dev dependencies

  • npm install --save-dev @rollup/plugin-commonjs @rollup/plugin-inject @rollup/plugin-node-resolve

Then include the following in your rollup.config.js

+import nodeResolve from "@rollup/plugin-node-resolve";
+import cjs from "@rollup/plugin-commonjs";
+import shim from "rollup-plugin-shim";
+import inject from "@rollup/plugin-inject";

export default {
  // other configs
  plugins: [
+    shim({
+      fs: `export default {}`,
+      net: `export default {}`,
+      tls: `export default {}`,
+      path: `export default {}`,
+      dns: `export function resolve() { }`,
+    }),
+    nodeResolve({
+      mainFields: ["module", "browser"],
+      preferBuiltins: false,
+    }),
+    cjs(),
+    inject({
+      modules: {
+        Buffer: ["buffer", "Buffer"],
+        process: "process",
+      },
+      exclude: ["./**/package.json"],
+    }),

Please consult the documentation of your favorite bundler for more information on using polyfills.

React Native Support

Similar to browsers, React Native does not support some JavaScript api used by this SDK library so you need to provide polyfills for them. Please see the Messaging React Native sample with Expo for more details.

Authenticate the client

Interaction with Service Bus starts with an instance of the ServiceBusClient class. You can authenticate to Service Bus using a connection string or using an Azure Active Directory credential.

Using a connection string

This method takes the connection string to your Service Bus instance. You can get the connection string from the Azure portal.

const { ServiceBusClient } = require("@azure/service-bus");

const serviceBusClient = new ServiceBusClient("<connectionString>");

More information about this constructor is available in the API documentation.

Using an Azure Active Directory Credential

Authentication with Azure Active Directory uses the Azure Identity library.

The example below uses the DefaultAzureCredential, one of many available credential providers from the @azure/identity library.

const { ServiceBusClient } = require("@azure/service-bus");
const { DefaultAzureCredential } = require("@azure/identity");

const fullyQualifiedNamespace = "<name-of-service-bus-namespace>.servicebus.windows.net";
const credential = new DefaultAzureCredential();
const serviceBusClient = new ServiceBusClient(fullyQualifiedNamespace, credential);

NOTE: If you're using your own implementation of the TokenCredential interface against AAD, then set the "scopes" for service-bus to the following to get the appropriate token:


More information about this constructor is available in the API documentation

Key concepts

Once you've initialized a ServiceBusClient, you can interact with these resources within a Service Bus Namespace:

  • Queues: Allows for sending and receiving messages. Often used for point-to-point communication.
  • Topics: As opposed to Queues, Topics are better suited to publish/subscribe scenarios. A topic can be sent to, but requires a subscription, of which there can be multiple in parallel, to consume from.
  • Subscriptions: The mechanism to consume from a Topic. Each subscription is independent, and receives a copy of each message sent to the topic. Rules and Filters can be used to tailor which messages are received by a specific subscription.

For more information about these resources, see What is Azure Service Bus?.

To interact with these resources, one should be familiar with the following SDK concepts:

Please note that the Queues, Topics and Subscriptions should be created prior to using this library.


The following sections provide code snippets that cover some of the common tasks using Azure Service Bus

Send messages

Once you have created an instance of a ServiceBusClient class, you can get a ServiceBusSender using the createSender method which you can use to send messages.

const sender = serviceBusClient.createSender("my-queue");

const messages = [
  { body: "Albert Einstein" },
  { body: "Werner Heisenberg" },
  { body: "Marie Curie" },
  { body: "Steven Hawking" },
  { body: "Isaac Newton" },
  { body: "Niels Bohr" },
  { body: "Michael Faraday" },
  { body: "Galileo Galilei" },
  { body: "Johannes Kepler" },
  { body: "Nikolaus Kopernikus" }

// sending a single message
await sender.sendMessages(messages[0]);

// sending multiple messages in a single call
// this will fail if the messages cannot fit in a batch
await sender.sendMessages(messages);

// Sends multiple messages using one or more ServiceBusMessageBatch objects as required
let batch = await sender.createMessageBatch();

for (let i = 0; i < messages.length; i++) {
  const message = messages[i];
  if (!batch.tryAddMessage(message)) {
    // Send the current batch as it is full and create a new one
    await sender.sendMessages(batch);
    batch = await sender.createMessageBatch();

    if (!batch.tryAddMessage(messages[i])) {
      throw new Error("Message too big to fit in a batch");
// Send the batch
await sender.sendMessages(batch);

Receive messages

Once you have created an instance of a ServiceBusClient class, you can get a ServiceBusReceiver using the createReceiver method.

const receiver = serviceBusClient.createReceiver("my-queue");

There are two receiveModes available.

  • "peekLock" - In peekLock mode, the receiver has a lock on the message for the duration specified on the queue.
  • "receiveAndDelete" - In receiveAndDelete mode, messages are deleted from Service Bus as they are received.

If the receiveMode is not provided in the options, it defaults to the "peekLock" mode. You can also settle the messages received in "peekLock" mode.

You can use this receiver in one of 3 ways to receive messages:

Get an array of messages

Use the receiveMessages function which returns a promise that resolves to an array of messages.

const myMessages = await receiver.receiveMessages(10);

Subscribe using a message handler

Use the subscribe method to set up message handlers and have it running as long as you need.

When you are done, call receiver.close() to stop receiving any more messages.

const myMessageHandler = async (message) => {
  // your code here
  console.log(`message.body: ${message.body}`);
const myErrorHandler = async (args) => {
    `Error occurred with ${args.entityPath} within ${args.fullyQualifiedNamespace}: `,
  processMessage: myMessageHandler,
  processError: myErrorHandler

Use async iterator

Use the getMessageIterator to get an async iterator over messages

for await (let message of receiver.getMessageIterator()) {
  // your code here

Settle a message

Once you receive a message you can call completeMessage(), abandonMessage(), deferMessage() or deadLetterMessage() on the receiver based on how you want to settle the message.

To learn more, please read Settling Received Messages

Dead letter queues

The dead letter queue is a sub-queue. Each queue or subscription has its own dead letter queue. Dead letter queues store messages that have been explicitly dead lettered (via receiver.deadLetterMessage()), or messages that have exceeded their maximum delivery count.

Creating a receiver for a dead letter sub-queue is similar to creating a receiver for a subscription or queue:

// To receive from a queue's dead letter sub-queue
const deadLetterReceiverForQueue = serviceBusClient.createReceiver("queue", {
  subQueueType: "deadLetter"

// To receive from a subscription's dead letter sub-queue
const deadLetterReceiverForSubscription = serviceBusClient.createReceiver("topic", "subscription", {
  subQueueType: "deadLetter"

// Dead letter receivers work like any other receiver connected to a queue
// ex:
const messages = await deadLetterReceiverForQueue.receiveMessages(5);

for (const message of messages) {
  console.log(`Dead lettered message: ${message.body}`);

Full samples demonstrating dead letter queues more thoroughly:

Send messages using Sessions

Using sessions requires you to create a session enabled Queue or Subscription. You can read more about how to configure this feature in the portal here.

In order to send messages to a session, use the ServiceBusClient to create a sender using createSender.

When sending the message, set the sessionId property in the message to ensure your message lands in the right session.

const sender = serviceBusClient.createSender("my-session-queue");
await sender.sendMessages({
  body: "my-message-body",
  sessionId: "my-session"

You can read more about how sessions work here.

Receive messages from Sessions

Using sessions requires you to create a session enabled Queue or Subscription. You can read more about how to configure this feature in the portal here.

Unlike non-session-enabled Queues or Subscriptions, only a single receiver can read from a session at any time. This is enforced by locking a session, which is handled by Service Bus. Conceptually, this is similar to how message locking works when using peekLock mode - when a message (or session) is locked your receiver has exclusive access to it.

In order to open and lock a session, use an instance of ServiceBusClient to create a SessionReceiver.

There are two ways of choosing which session to open:

  1. Specify a sessionId, which locks a named session.

    const receiver = await serviceBusClient.acceptSession("my-session-queue", "my-session");
  2. Do not specify a session id. In this case Service Bus will find the next available session that is not already locked.

    const receiver = await serviceBusClient.acceptNextSession("my-session-queue");

    You can find the name of the session via the sessionId property on the SessionReceiver. If the receiveMode is not provided in the options, it defaults to the "peekLock" mode. You can also settle the messages received in "peekLock" mode.

Once the receiver is created you can use choose between 3 ways to receive messages:

You can read more about how sessions work here.

Manage resources of a service bus namespace

ServiceBusAdministrationClient lets you manage a namespace with CRUD operations on the entities(queues, topics, and subscriptions) and on the rules of a subscription.

  • Supports authentication with a service bus connection string as well as with the AAD credentials from @azure/identity similar to the ServiceBusClient.

Note: Service Bus doesn't support setting CORS rules for namespaces yet, hence ServiceBusAdministrationClient won't work in the browser without disabling web-security. For more info, refer here.

// Get the connection string from the portal
// OR
// use the token credential overload, provide the host name of your Service Bus instance and the AAD credentials from the @azure/identity library
const serviceBusAdministrationClient = new ServiceBusAdministrationClient("<connectionString>");

// Similarly, you can create topics and subscriptions as well.
const createQueueResponse = await serviceBusAdministrationClient.createQueue(queueName);
console.log("Created queue with name - ", createQueueResponse.name);

const queueRuntimeProperties = await serviceBusAdministrationClient.getQueueRuntimeProperties(
console.log("Number of messages in the queue = ", queueRuntimeProperties.totalMessageCount);

await serviceBusAdministrationClient.deleteQueue(queueName);


Here's some initial steps to start diagnosing issues. For more information please refer to the Service Bus Troubleshooting Guide.

AMQP Dependencies

The Service Bus library depends on the rhea-promise library for managing connections, sending and receiving messages over the AMQP protocol.


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

  • Getting debug logs from the Service Bus SDK
export DEBUG=azure*
  • Getting debug logs from the Service Bus SDK and the protocol level library.
export DEBUG=azure*,rhea*
  • If you are not interested in viewing the message transformation (which consumes lot of console/disk space) then you can set the DEBUG environment variable as follows:
export DEBUG=azure*,rhea*,-rhea:raw,-rhea:message,-azure:core-amqp:datatransformer
  • If you are interested only in errors, then you can set the DEBUG environment variable as follows:
export DEBUG=azure:service-bus:error,azure:core-amqp:error,rhea-promise:error,rhea:events,rhea:frames,rhea:io,rhea:flow

Logging to a file

  1. Set the DEBUG environment variable as shown above
  2. Run your test script as follows:
  • Logging statements from your test script go to out.log and logging statements from the sdk go to debug.log.
    node your-test-script.js > out.log 2>debug.log
  • Logging statements from your test script and the sdk go to the same file out.log by redirecting stderr to stdout (&1), and then redirect stdout to a file:
    node your-test-script.js >out.log 2>&1
  • Logging statements from your test script and the sdk go to the same file out.log.
      node your-test-script.js &> out.log

Next steps

Please take a look at the samples directory for detailed examples on how to use this library to send and receive messages to/from Service Bus Queues, Topics and Subscriptions.


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.


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