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What are Message Queues? How do Message Queues work?



Messaging queues are an essential component of modern software architecture. Message Queues play a critical role in enabling communication between different applications and systems. They are in charge of controlling the communication between software applications. This guarantees reliable and effective data delivery. But what are messaging queues exactly, and how do they operate?


If you’re new to modern systems architecture, it can get confusing wrapping your head around message queues, their benefits, and their types.


In this article, we will examine the fundamentals of messaging queues, their notable characteristics, and their application in software systems. That’s why we’ve prepared a detailed guide to help you understand what message queues are, why we need them, and how they work. We’ll also go through the different message queues and show their different use cases.


Whether you are a software developer, architect, or simply interested in understanding the underlying mechanics of software communication, this blog will provide you with a comprehensive overview of messaging queues and their inner workings.


Let's dive right in -


What are Message Queues?

Applications constantly receive and send data and they need to communicate with each other for improved performance and functionality. Data is received and stored as messages.


Message Queues
Message Queue

A message queue allows different applications and services to communicate, enabling systems to work efficiently through a smooth flow of information. You can send one message to multiple applications at the same time. They break applications apart so they can communicate in asynchronous communication.


Message - The data needed to be transmitted, which is available in different formats.

Queue - Order of the message received from the producer to the consumer. It works on a First-In-First-Out basis, meaning the message that was received first will be the first to be sent.


Types of Message Queues

Point-to-point model

A point-to-point message queue facilitates communication from one application to another. When a consumer receives a message, it sends a confirmation to the producer so that it can delete the message from the queue. A specific consumer application receives each message in the queue.


Message Queue - Point to Point Model
Message Queue - Point to Point Model


Publish/Subscribe model

Publish/Subscribe, also known as Pub/Sub, sends a message to all the subscribers (consumers), by duplicating the message before sending it for processing. If there are no consumers available for the message, it automatically gets rejected.


Message Queue - Publish/Subscribe model
Message Queue - Publish/Subscribe model


Benefits of Message Queues

Decoupling

When using message queues, messages aren’t dependent on each other. It allows you to use each application for specific work without having to test how processes affect other services or applications.


Unlike Monolithic applications, Microservices give you the power to separate services, allowing separate items to occur.


Increased Reliability

Message queues allow applications to work separately, which gives them a high tolerance to faults and reduces the chances of data loss and errors.


It allows you to run other services or queues even if you can’t access one part of your system.


Scalability

Queues let you use one application at a time, making it easy to swap or add components as your code develops. You can also use different languages in each application without worrying if your system will work.


As requests increase, message queues allow you to distribute the workload across the different consumers available. This lets you balance the load easily when requests are high or when one server isn’t available.


Better Performance

Message queues enable asynchronous communication, meaning tasks are independent of each other. You can add requests to the queue without having to wait for replies for processes to run.

This reduces delays in an application and improves the user experience.


Reduced Deployment Time

Developers can create applications and systems separately that aren’t dependent on each other. Queues make it easy to add features and codebases with a totally different pipeline.


The reduced dependency improves the time taken to deploy services and increases the developer’s productivity.


Easy Monitoring

With message queues, you can track message transmissions, the number of messages in a queue, and the rate at which messages are processed. It becomes useful when you want to know how data flows through your system.


Improved communication

The microservice architecture allows applications to function and communicate without relying on replies from each other. Services can push messages asynchronously and ensure they reach the intended consumers without experiencing system delays.


Examples of Message Queues

RabbitMQ

RabbitMQ is one of the popular message brokers and is an implementation of the Advanced Message Queueing Protocol (AMQP) message model. With RabbitMQ, the producer doesn’t produce messages directly to a message queue but uses an exchange.


RabbitMQ Message Queue Architecture
RabbitMQ Message Queue Architecture

The exchange receives the message and distributes it according to how it’s addressed.

It connects the exchange to queues through connections called binding, which can be referenced by a binding key, while the consumers subscribe to the queues. Different exchanges offer flexibility in how messages move in the system.


Types of Exchanges in RabbitMQ

  • Fanout exchange - The exchange receives a message and duplicates it before sending it to every queue it knows.

  • Direct exchange - The producer produces a message, and the message gets a routing key, which is compared to the binding key. If the two keys are a match, the message moves through the system and to the specific consumer.

  • Topic exchange - It runs a partial match between the routing key and the binding key.

  • Header exchange - The routing key is completely ignored, and it moves the message through the system according to its header.

  • Default exchange - This type of exchange is unique to RabbitMQ, and is also referred to as the nameless exchange. The routing key is tied to the queue, and if it has a similar name, the message will move through there.


Benefits of using RabbitMQ

  • Cross-language communication

  • Flexibility moving messages

  • Cloud friendly

  • Great browser-based management UI

To know more about RabbitMQ, check out this article.

Official site of RabbitMQ: https://www.rabbitmq.com/


Apache Kafka

Apache Kafka is an open-source distributed platform that allows the development of real-time applications. It allows developers to build applications that produce and consume streams of data records. The records produced allow multiple users to use the application at the same time without compromising the system’s performance.


Apache Kafka Message Queue Architecture
Apache Kafka Message Queue Architecture

Apache Kafka core APIs

  • Producer API: This allows your application to produce streams of data. It creates records and produces them in topics.

  • Consumer API: It subscribes to one or more topics.

  • Streams API: Leverages consumer and producer API to consume topics and transform data in real-time. It’s popularly used in cases of data collection and location tracking.

  • Connector API: Enables you to write connectors which are reusable consumers and producers used to integrate data sources. With a connector API, you don’t have to write code every time. You only have to configure your data source.


Benefits of using Apache Kafka

  • High data accuracy

  • Resilient and minimal errors

  • Maintain order of occurrence

  • Best in location tracking and data collection


Conclusion

Message queues improve system performance and reliability, which improves the user experience. They help show progress and eliminate the flooding of queues.


Before selecting the type of message queue, consider what your system needs to offload, the pros and cons of that broker, and if it meets your needs. Cloud-native architecture requires different pieces to work together and using message queues makes the process efficient.



And that's a wrap! Hi, I am Gourav Dhar, a software developer and I write blogs on Backend Development and System Design. Subscribe to my Newsletter and learn something new every week - https://thegeekyminds.com/subscribe



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