Azure Queue Storage Reference

This document provides a comprehensive reference for Azure Queue storage, a service that stores large numbers of small messages that can be accessed from anywhere in the world via HTTP or HTTPS.

Overview

Azure Queue storage is a service that enables you to store large quantities of messages that can be accessed and processed by various components of an application. Each message is approximately 64 KB in size, and a queue can contain any number of messages, up to the limit of the storage account capacity.

Key Concepts

• Message: A unit of data stored in the queue. Messages can be processed asynchronously.
• Queue: A collection of messages.
• Visibility Timeout: When a message is dequeued, it becomes invisible to other clients for a specified duration. After this duration, if the message hasn't been deleted, it reappears in the queue.
• Dequeuing: The process of retrieving and processing a message from the queue.

Core Operations

Queue Operations

• Create Queue: Creates a new queue within the specified storage account.
• Delete Queue: Deletes an existing queue and all of its messages.
• List Queues: Retrieves a list of all queues within a storage account.
• Get Queue Metadata: Retrieves metadata about a specific queue, such as its approximate message count.

Message Operations

• Enqueue Message: Adds a message to the end of a queue.
• Dequeue Message: Retrieves and removes the next message from the front of the queue. The message becomes invisible for a specified visibilitytimeout.
• Peek Message: Retrieves the next message from the front of the queue, but does not remove it. The message remains visible.
• Peek Messages: Retrieves a list of messages from the front of the queue, but does not remove them.
• Get Messages: Retrieves one or more messages from the front of the queue. The messages become invisible for a specified visibilitytimeout.
• Clear Messages: Deletes all messages from a queue.
• Delete Message: Deletes a specific message from the queue using its messageid and popreceipt.

REST API Reference

The Azure Queue Storage REST API allows you to interact with queues and messages programmatically. Below are some common endpoints:

Queues

Operation	HTTP Method	URL	Description
Create Queue	PUT	/{accountName}/queues/{queueName}	Creates a new queue.
Delete Queue	DELETE	/{accountName}/queues/{queueName}	Deletes an existing queue.
List Queues	GET	/{accountName}/queues	Retrieves a list of queues.
Get Queue Metadata	GET	/{accountName}/queues/{queueName}?comp=metadata	Retrieves queue metadata.

Messages

Operation	HTTP Method	URL	Description
Enqueue Message	POST	/{accountName}/queues/{queueName}/messages	Adds a message to a queue.
Dequeue Message	GET	/{accountName}/queues/{queueName}/messages?numofmessages=1&visibilitytimeout={seconds}	Dequeues a message.
Peek Message	GET	/{accountName}/queues/{queueName}/messages?peekonly=true	Peeks at a message.
Delete Message	DELETE	/{accountName}/queues/{queueName}/messages/{messageid}	Deletes a specific message. Requires popreceipt in the request header.
Clear Messages	DELETE	/{accountName}/queues/{queueName}/messages	Clears all messages from a queue.

SDK Examples (Conceptual)

Enqueueing a Message (.NET)

using Azure.Storage.Queues;

string connectionString = "YOUR_AZURE_STORAGE_CONNECTION_STRING";
string queueName = "my-tasks-queue";
string messageText = "Process this report.";

// Instantiate a QueueClient
QueueClient queueClient = new QueueClient(connectionString, queueName);

// Create the queue if it doesn't exist
queueClient.CreateIfNotExists();

// Enqueue the message
SendReceipt sendReceipt = queueClient.SendMessage(messageText);

Console.WriteLine($"Message sent with ID: {sendReceipt.MessageId}");
            

Dequeuing and Processing a Message (Python)

from azure.storage.queue import QueueClient

connection_string = "YOUR_AZURE_STORAGE_CONNECTION_STRING"
queue_name = "my-tasks-queue"

# Instantiate a QueueClient
queue_client = QueueClient.from_connection_string(connection_string, queue_name)

# Receive and delete message
response = queue_client.receive_message()

if response:
    message_id = response.id
    message_content = response.content
    pop_receipt = response.pop_receipt

    print(f"Received message ID: {message_id}")
    print(f"Message content: {message_content}")

    # Process the message here...

    # Delete the message after successful processing
    queue_client.delete_message(message_id, pop_receipt)
    print(f"Message {message_id} deleted.")
else:
    print("No messages in the queue.")
            

Best Practices

• Use appropriate visibilitytimeout values to avoid message loss during processing.
• Consider message batching for efficiency when dealing with large volumes.
• Implement robust error handling and retry mechanisms.
• Monitor queue lengths and message processing times.