Send messages to an Azure Service Bus topic and receive messages from subscriptions to the topic (JavaScript)

To use this quickstart with your own Azure account, you need:

• Install Azure CLI, which provides the passwordless authentication to your developer machine.
• Sign in with your Azure account at the terminal or command prompt with az login.
• Use the same account when you add the appropriate role to your resource.
• Run the code in the same terminal or command prompt.
• Note down your topic name and subscription for your Service Bus namespace. You'll need that in the code.

Note down the following, which you'll use in the code below:

• Service Bus namespace connection string
• Service Bus namespace topic name you created
• Service Bus namespace subscription

Assign roles to your Azure AD user

When developing locally, make sure that the user account that connects to Azure Service Bus has the correct permissions. You'll need the Azure Service Bus Data Owner role in order to send and receive messages. To assign yourself this role, you'll need the User Access Administrator role, or another role that includes the Microsoft.Authorization/roleAssignments/write action. You can assign Azure RBAC roles to a user using the Azure portal, Azure CLI, or Azure PowerShell. Learn more about the available scopes for role assignments on the scope overview page.

The following example assigns the Azure Service Bus Data Owner role to your user account, which provides full access to Azure Service Bus resources. In a real scenario, follow the Principle of Least Privilege to give users only the minimum permissions needed for a more secure production environment.

Azure built-in roles for Azure Service Bus

For Azure Service Bus, the management of namespaces and all related resources through the Azure portal and the Azure resource management API is already protected using the Azure RBAC model. Azure provides the below Azure built-in roles for authorizing access to a Service Bus namespace:

• Azure Service Bus Data Owner: Enables data access to Service Bus namespace and its entities (queues, topics, subscriptions, and filters). A member of this role can send and receive messages from queues or topics/subscriptions.
• Azure Service Bus Data Sender: Use this role to give the send access to Service Bus namespace and its entities.
• Azure Service Bus Data Receiver: Use this role to give the receive access to Service Bus namespace and its entities.

If you want to create a custom role, see Rights required for Service Bus operations.

Add Azure AD user to Azure Service Bus Owner role

Add your Azure AD user name to the Azure Service Bus Data Owner role at the Service Bus namespace level. It will allow an app running in the context of your user account to send messages to a queue or a topic, and receive messages from a queue or a topic's subscription.

1. If you don't have the Service Bus Namespace page open in the Azure portal, locate your Service Bus namespace using the main search bar or left navigation.

2. On the overview page, select Access control (IAM) from the left-hand menu.

3. On the Access control (IAM) page, select the Role assignments tab.

4. Select + Add from the top menu and then Add role assignment from the resulting drop-down menu.

   

5. Use the search box to filter the results to the desired role. For this example, search for Azure Service Bus Data Owner and select the matching result. Then choose Next.

6. Under Assign access to, select User, group, or service principal, and then choose + Select members.

7. In the dialog, search for your Azure AD username (usually your user@domain email address) and then choose Select at the bottom of the dialog.

8. Select Review + assign to go to the final page, and then Review + assign again to complete the process.

Get the connection string

Creating a new namespace automatically generates an initial Shared Access Signature (SAS) policy with primary and secondary keys, and primary and secondary connection strings that each grant full control over all aspects of the namespace. See Service Bus authentication and authorization for information about how to create rules with more constrained rights for regular senders and receivers.

A client can use the connection string to connect to the Service Bus namespace. To copy the primary connection string for your namespace, follow these steps:

1. On the Service Bus Namespace page, select Shared access policies on the left menu.

2. On the Shared access policies page, select RootManageSharedAccessKey.

3. In the Policy: RootManageSharedAccessKey window, select the copy button next to Primary Connection String, to copy the connection string to your clipboard for later use. Paste this value into Notepad or some other temporary location.

   

   You can use this page to copy primary key, secondary key, primary connection string, and secondary connection string.

1. To install the required npm package(s) for Service Bus, open a command prompt that has npm in its path, change the directory to the folder where you want to have your samples and then run this command.

2. Install the following packages:

   npm install @azure/service-bus @azure/identity
   

1. To install the required npm package(s) for Service Bus, open a command prompt that has npm in its path, change the directory to the folder where you want to have your samples and then run this command.

2. Install the following package:

   npm install @azure/service-bus
   

You must have signed in with the Azure CLI's az login in order for your local machine to provide the passwordless authentication required in this code.

1. Open your favorite editor, such as Visual Studio Code

2. Create a file called sendtotopic.js and paste the below code into it. This code will send a message to your topic.

   const { ServiceBusClient } = require("@azure/service-bus");
   const { DefaultAzureCredential } = require("@azure/identity");
   
   // Replace `<SERVICE-BUS-NAMESPACE>` with your namespace
   const fullyQualifiedNamespace = "<SERVICE-BUS-NAMESPACE>.servicebus.chinacloudapi.cn";
   
   // Passwordless credential
   const credential = new DefaultAzureCredential();
   
   const topicName = "<TOPIC NAME>";
   
   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" }
    ];
   
    async function main() {
   	// create a Service Bus client using the passwordless authentication to the Service Bus namespace
   	const sbClient = new ServiceBusClient(fullyQualifiedNamespace, credential);
   
   	// createSender() can also be used to create a sender for a queue.
   	const sender = sbClient.createSender(topicName);
   
   	try {
   		// Tries to send all messages in a single batch.
   		// Will fail if the messages cannot fit in a batch.
   		// await sender.sendMessages(messages);
   
   		// create a batch object
   		let batch = await sender.createMessageBatch(); 
   		for (let i = 0; i < messages.length; i++) {
   			// for each message in the arry			
   
   			// try to add the message to the batch
   			if (!batch.tryAddMessage(messages[i])) {			
   				// if it fails to add the message to the current batch
   				// send the current batch as it is full
   				await sender.sendMessages(batch);
   
   				// then, create a new batch 
   				batch = await sender.createMessageBatch();
   
   				// now, add the message failed to be added to the previous batch to this batch
   				if (!batch.tryAddMessage(messages[i])) {
   					// if it still can't be added to the batch, the message is probably too big to fit in a batch
   					throw new Error("Message too big to fit in a batch");
   				}
   			}
   		}
   
   		// Send the last created batch of messages to the topic
   		await sender.sendMessages(batch);
   
   		console.log(`Sent a batch of messages to the topic: ${topicName}`);
   
   		// Close the sender
   		await sender.close();
   	} finally {
   		await sbClient.close();
   	}
   }
   
   // call the main function
   main().catch((err) => {
   	console.log("Error occurred: ", err);
   	process.exit(1);
    });    
   

3. Replace <SERVICE BUS NAMESPACE CONNECTION STRING> with the connection string to your Service Bus namespace.

4. Replace <TOPIC NAME> with the name of the topic.

5. Then run the command in a command prompt to execute this file.

   node sendtotopic.js 
   

6. You should see the following output.

   Sent a batch of messages to the topic: mytopic
   

1. Open your favorite editor, such as Visual Studio Code

2. Create a file called sendtotopic.js and paste the below code into it. This code will send a message to your topic.

   const { ServiceBusClient } = require("@azure/service-bus");
   
   const connectionString = "<SERVICE BUS NAMESPACE CONNECTION STRING>"
   const topicName = "<TOPIC NAME>";
   
   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" }
    ];
   
    async function main() {
   	// create a Service Bus client using the connection string to the Service Bus namespace
   	const sbClient = new ServiceBusClient(connectionString);
   
   	// createSender() can also be used to create a sender for a queue.
   	const sender = sbClient.createSender(topicName);
   
   	try {
   		// Tries to send all messages in a single batch.
   		// Will fail if the messages cannot fit in a batch.
   		// await sender.sendMessages(messages);
   
   		// create a batch object
   		let batch = await sender.createMessageBatch(); 
   		for (let i = 0; i < messages.length; i++) {
   			// for each message in the arry			
   
   			// try to add the message to the batch
   			if (!batch.tryAddMessage(messages[i])) {			
   				// if it fails to add the message to the current batch
   				// send the current batch as it is full
   				await sender.sendMessages(batch);
   
   				// then, create a new batch 
   				batch = await sender.createMessageBatch();
   
   				// now, add the message failed to be added to the previous batch to this batch
   				if (!batch.tryAddMessage(messages[i])) {
   					// if it still can't be added to the batch, the message is probably too big to fit in a batch
   					throw new Error("Message too big to fit in a batch");
   				}
   			}
   		}
   
   		// Send the last created batch of messages to the topic
   		await sender.sendMessages(batch);
   
   		console.log(`Sent a batch of messages to the topic: ${topicName}`);
   
   		// Close the sender
   		await sender.close();
   	} finally {
   		await sbClient.close();
   	}
   }
   
   // call the main function
   main().catch((err) => {
   	console.log("Error occurred: ", err);
   	process.exit(1);
    });    
   

3. Replace <SERVICE BUS NAMESPACE CONNECTION STRING> with the connection string to your Service Bus namespace.

4. Replace <TOPIC NAME> with the name of the topic.

5. Then run the command in a command prompt to execute this file.

   node sendtotopic.js 
   

6. You should see the following output.

   Sent a batch of messages to the topic: mytopic
   

You must have signed in with the Azure CLI's az login in order for your local machine to provide the passwordless authentication required in this code.

1. Open your favorite editor, such as Visual Studio Code

2. Create a file called receivefromsubscription.js and paste the following code into it. See code comments for details.

   const { delay, ServiceBusClient, ServiceBusMessage } = require("@azure/service-bus");
   const { DefaultAzureCredential } = require("@azure/identity");
   
   // Replace `<SERVICE-BUS-NAMESPACE>` with your namespace
   const fullyQualifiedNamespace = "<SERVICE-BUS-NAMESPACE>.servicebus.chinacloudapi.cn";
   
   // Passwordless credential
   const credential = new DefaultAzureCredential();
   
   const topicName = "<TOPIC NAME>";
   const subscriptionName = "<SUBSCRIPTION NAME>";
   
    async function main() {
   	// create a Service Bus client using the passwordless authentication to the Service Bus namespace
   	const sbClient = new ServiceBusClient(fullyQualifiedNamespace, credential);
   
   	// createReceiver() can also be used to create a receiver for a queue.
   	const receiver = sbClient.createReceiver(topicName, subscriptionName);
   
   	// function to handle messages
   	const myMessageHandler = async (messageReceived) => {
   		console.log(`Received message: ${messageReceived.body}`);
   	};
   
   	// function to handle any errors
   	const myErrorHandler = async (error) => {
   		console.log(error);
   	};
   
   	// subscribe and specify the message and error handlers
   	receiver.subscribe({
   		processMessage: myMessageHandler,
   		processError: myErrorHandler
   	});
   
   	// Waiting long enough before closing the sender to send messages
   	await delay(5000);
   
   	await receiver.close();	
   	await sbClient.close();
   }
   
   // call the main function
   main().catch((err) => {
   	console.log("Error occurred: ", err);
   	process.exit(1);
    });    
   

3. Replace <SERVICE BUS NAMESPACE CONNECTION STRING> with the connection string to the namespace.

4. Replace <TOPIC NAME> with the name of the topic.

5. Replace <SUBSCRIPTION NAME> with the name of the subscription to the topic.

6. Then run the command in a command prompt to execute this file.

   node receivefromsubscription.js
   

1. Open your favorite editor, such as Visual Studio Code

2. Create a file called receivefromsubscription.js and paste the following code into it. See code comments for details.

   const { delay, ServiceBusClient, ServiceBusMessage } = require("@azure/service-bus");
   
   const connectionString = "<SERVICE BUS NAMESPACE CONNECTION STRING>"
   const topicName = "<TOPIC NAME>";
   const subscriptionName = "<SUBSCRIPTION NAME>";
   
    async function main() {
   	// create a Service Bus client using the connection string to the Service Bus namespace
   	const sbClient = new ServiceBusClient(connectionString);
   
   	// createReceiver() can also be used to create a receiver for a queue.
   	const receiver = sbClient.createReceiver(topicName, subscriptionName);
   
   	// function to handle messages
   	const myMessageHandler = async (messageReceived) => {
   		console.log(`Received message: ${messageReceived.body}`);
   	};
   
   	// function to handle any errors
   	const myErrorHandler = async (error) => {
   		console.log(error);
   	};
   
   	// subscribe and specify the message and error handlers
   	receiver.subscribe({
   		processMessage: myMessageHandler,
   		processError: myErrorHandler
   	});
   
   	// Waiting long enough before closing the sender to send messages
   	await delay(5000);
   
   	await receiver.close();	
   	await sbClient.close();
   }
   
   // call the main function
   main().catch((err) => {
   	console.log("Error occurred: ", err);
   	process.exit(1);
    });    
   

3. Replace <SERVICE BUS NAMESPACE CONNECTION STRING> with the connection string to the namespace.

4. Replace <TOPIC NAME> with the name of the topic.

5. Replace <SUBSCRIPTION NAME> with the name of the subscription to the topic.

6. Then run the command in a command prompt to execute this file.

   node receivefromsubscription.js