RabbitMQ vs. Kafka

Processing, storing, and sending data is at the heart of how we communicate and get business done. This involves implementing various applications, software, and mobile devices that together form an intricate web to process data and information. Programmers will often use message brokers to facilitate this constant flow of information.

Message brokers and Pub/Sub messaging systems are instrumental in allowing applications, services, and systems to communicate effectively. RabbitMQ and Kafka are types of software that play an important role in processing data and sending messages. The following is everything you should know about RabbitMQ and Kafka.

What are message brokers?

Message brokers are software that enables various systems, services, and applications to exchange information and communicate with one another. In simplest terms, message brokers act as a middleman for different services, such as a web application. 

The process takes place when your message broker translates messages between different messaging protocols. Interdependent services will “talk” to each other even if they are on different platforms or written in different languages.

Message brokers are within message-oriented middleware, or MOM, solutions. This provides them with a means of handling data flow between the components so they can focus on the core logic.

Message brokers can validate, store, and send messages to the correct destinations. This can occur even if senders don’t know where receivers are or even if they are active. This process involves decoupling within systems. 

What are pub/sub messaging systems?

Publish/Subscribe (Pub/Sub) messaging systems are a type of service-to-service communication. Pub/Sub is primarily in use in microservices and serverless architectures. The Pub/Sub model means that all your subscribers to a topic immediately receive the messages after publishing.

The Pub/Sub model enables the sending of messages asynchronously, which allows your program to begin an extensive task while still maintaining the ability to respond to other events, even while the task is still running.

In cloud architecture, applications are often decoupled, or separate. These smaller, separate building blocks are easier to develop and maintain. Pub/Sub messaging can provide instant notification for distributed applications.

To increase performance, scalability, and reliability, you can use Pub/Sub messaging that enables the decoupling of applications and event-driven architectures. There are four basic concepts that make up the Pub/Sub model:

  • Topic: This is the channel that maintains subscribers to receive messages. Unlike queues that batch messages, a message topic will transfer a message with very little or no queuing. 
  • Message: Messages are sent by a publisher to a topic, without the knowledge of the subscribers. 
  • Publisher: This is the application publishing messages to the topic. The publisher is also called the host.
  • Subscriber: This is an application registering itself with a particular topic so it can receive the correct messages.

What Is RabbitMQ?

RabbitMQ is open-source software that facilitates effective message delivery in various routing scenarios. It is a type of message broker that can work on-premises and in the cloud. The system has the ability to receive, deliver, and store data messages. RabbitMQ was released in 2007.

  • Architecture: RabbitMQ has a “Hello World” style of architecture
  • Language Written In: Erlang
  • Primary Uses: It is a general-purpose message broker that supports Go, Elixir, Java, JavaScript, PHP, Python, Ruby, Spring, Swift, .NET, and Objective-C. It offers protocols such as AMQP, HTTP, MQTT, and STOMP with plug-ins. 

RabbitMQ is primarily for processing reliable background jobs and high throughput. Developers also use it for intercommunication and integration within applications and for performing complex routing. Other tasks it’s good for include the following:

  • Working with rapid request-response web servers
  • Sharing loads between workers that have high load
  • Long-running tasks such as PDF conversion or image scaling
  • General integration and communication within and between applications

RabbitMQ has a message broker design that enables it to excel in cases that have per-message guarantees and specific routing needs. Specific features of RabbitMQ include the following:

  • RabbitMQ can communicate asynchronously or synchronously
  • It’s a general message broker that uses variations of Pub/Sub communications and request/reply patterns
  • The broker in RabbitMQ monitors the consumer state and provides consistent delivery of messages at basically the same speed
  • Rabbit MQ works well with Ruby, Java, and client libraries

What Is Kafka?

Kafka is also an open-source system that commercially supports Pub/Sub messaging. Kafka is a newer tool than RabbitMQ, released in 2011. It was built mainly for streaming scenarios and data replay. Kafka stores records in different categories that are called topics. In each topic, the software keeps a partitioned log of messages.

  • Architecture: Kafka has “event-driven” architecture, which can be extended with plug-in architecture. Kafka uses a pull-based system that allows users to request messages from particular offsets. 
  • Language Written In: Java and Scala
  • Primary Uses: Uses include activity tracking, such as monitoring user clicks and how much time users spend on certain pages. Other uses include real-time data processing, operational metrics, log aggregation, and messaging. It is ideal when you have several microservices that should communicate asynchronously. 

Kafka has three basic components. 

  • Kafka: This is a backend application that enables you to share streams between applications.
  • Kafka Streams: This transforms data in Kafka. The API for writing applications allows the data processing to happen within the client application.
  • Kafka Connect: This is a pluggable integration to other applications, and it allows you to move data in and out of Kafka.

Kafka offers an adapter SDK, so programmers can build their own integration system. Technically, however, Kafka ships with a Java client. Users can operate the platform to:

  • Stream from A to B without having to implement complex routing
  • Stream processing and event sourcing
  • Process data through multi-stage pipelines
  • Work through modeling changes as a sequence of events
  • Read, store, and analyze a data stream
  • Regularly audit systems

What are the differences between RabbitMQ and Kafka?

Some developers may see both these technologies as interchangeable. While there are some cases where RabbitMQ and Kafka are similar, there are distinct differences between the platforms. Ultimately, RabbitMQ is a message broker, while Kafka is a distributed streaming platform. One of the primary differences between the two is that Kafka is pull-based, while RabbitMQ is push-based.

A pull-based system waits for consumers to ask for data. A push-based system automatically sends or “pushes” messages to subscribed consumers. Each of these tools will therefore respond differently in various circumstances. A pull model makes sense for Kafka because of the way its data is structured. The message order is in a partition that allows users to leverage messages for higher throughput and more effective delivery.

RabbitMQ has a push model with a prefetch limit. This works well with low-latency messaging. The primary goal of a push model is the distribution of messages quickly, yet individually. It also includes processing messages at the approximate order in which they arrive in the queue.

Some other basic differences between RabbitMQ and Kafka include the following:

  • RabbitMQ can send approximately 4K–10K messages each second, while Kafka can send one million messages each second.
  • RabbitMQ has a consumer mode that is smart broker/dumb consumer. Kafka’s mode is dumb broker/smart consumer.
  • Message retention for RabbitMQ is acknowledgment based. Kafka’s message retention is policy-based.
  • RabbitMQ has no constraints on payload size. However, Kafka has a default of 1 MB limit.

What are the similarities between RabbitMQ and Kafka? 

Both Kafka and RabbitMQ serve the same general purposes in that they both handle messaging. They are commercially supported and serve similar roles. They accomplish these roles and tasks in different capacities.

Both Kafka and RabbitMQ use asynchronous messages to send information from producers to consumers. Both of these platforms are built for scale; however, the way to scale on each is different. Kafka implements horizontal scaling, while RabbitMQ is primarily for vertical scaling.

RabbitMQ vs. Kafka: which one should you choose?

Which one you choose depends on the requirements for your particular project. For example, if you’re looking for the best choice for microservices, RabbitMQ is a better choice for blocking tasks and for quicker server response times. Kafka, however, provides a high-performance routing approach that works well with big data use.

You would likely use Kafka for the following scenarios:

  • You need a pipeline to generate a graph of real-time data flows
  • You need to consume messages quickly
  • You need an application that requires a stream history so customers can see a replay

You would likely use RabbitMQ for the following scenarios:

  • You have applications that need various request/reply capabilities
  • You have applications that need legacy protocol support
  • You need flexibility when there is no clear end-to-end architecture

In conclusion, RabbitMQ is a solid general purpose message broker, while Kafka is a message bus optimized for streaming and replay. There are many similarities between RabbitMQ and Kafka, but there are obvious differences you’ll want to keep in mind when deciding which is the best choice for your particular project.

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