Send messages to and receive messages from Azure Service Bus queues (JavaScript)

In this tutorial, you learn how to use the @azure/service-bus package in a JavaScript program to send messages to and receive messages from a Service Bus queue.

Prerequisites

• An Azure subscription. To complete this tutorial, you need an Azure account. You can activate your MSDN subscriber benefits or sign-up for a free account.
• If you don't have a queue to work with, follow steps in the Use Azure portal to create a Service Bus queue article to create a queue. Note down the connection string for your Service Bus namespace and the name of the queue you created.

Use Node Package Manager (NPM) to install the package

To install the npm package 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.

npm install @azure/service-bus

Send messages to a queue

The following sample code shows you how to send a message to a queue.

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

2. Create a file called send.js and paste the below code into it. This code sends the names of scientists as messages to your queue.

   const { ServiceBusClient } = require("@azure/service-bus");
   
   // connection string to your Service Bus namespace
   const connectionString = "<CONNECTION STRING TO SERVICE BUS NAMESPACE>"
   
   // name of the queue
   const queueName = "<QUEUE 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 topic.
   	const sender = sbClient.createSender(queueName);
   
   	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 array			
   
   			// 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 queue
   		await sender.sendMessages(batch);
   
   		console.log(`Sent a batch of messages to the queue: ${queueName}`);
   
   		// 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 <CONNECTION STRING TO SERVICE BUS NAMESPACE> with the connection string to your Service Bus namespace.

4. Replace <QUEUE NAME> with the name of the queue.

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

   node send.js 
   

6. You should see the following output.

   Sent a batch of messages to the queue: myqueue
   

Receive messages from a queue

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

2. Create a file called receive.js and paste the following code into it.

   const { delay, ServiceBusClient, ServiceBusMessage } = require("@azure/service-bus");
   
   // connection string to your Service Bus namespace
   const connectionString = "<CONNECTION STRING TO SERVICE BUS NAMESPACE>"
   
   // name of the queue
   const queueName = "<QUEUE 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 subscription.
   	const receiver = sbClient.createReceiver(queueName);
   
   	// 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(20000);
   
   	await receiver.close();	
   	await sbClient.close();
   }    
   // call the main function
   main().catch((err) => {
   	console.log("Error occurred: ", err);
   	process.exit(1);
    });
   

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

4. Replace <QUEUE NAME> with the name of the queue.

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

   node receive.js
   

6. You should see the following output.

   Received message: Albert Einstein
   Received message: Werner Heisenberg
   Received message: Marie Curie
   Received message: Steven Hawking
   Received message: Isaac Newton
   Received message: Niels Bohr
   Received message: Michael Faraday
   Received message: Galileo Galilei
   Received message: Johannes Kepler
   Received message: Nikolaus Kopernikus
   

On the Overview page for the Service Bus namespace in the Azure portal, you can see incoming and outgoing message count. You may need to wait for a minute or so and then refresh the page to see the latest values.

Select the queue on this Overview page to navigate to the Service Bus Queue page. You see the incoming and outgoing message count on this page too. You also see other information such as the current size of the queue, maximum size, active message count, and so on.

Next steps

See the following documentation and samples:

• Azure Service Bus client library for JavaScript
• JavaScript samples
• TypeScript samples
• API reference documentation