Welcome to this interesting blog where we talk about microservices architecture and not just that we are going to talk about a very powerful message broker that is going to play a very important role in helping with asynchronous and reliable messaging between services.
The thing with microservices architecture is that within it all the different services communicate with each other so that they can do a lot of tasks.
However, in order to do that the internal service communication should be reliable and also ready for growth.
If that is not the case then we can find problems such as loss of messages and service failure and even complicated challenges such as network disruptions.
The problem with some of these challenges is that they will compromise the integrity of the system.
Something like this can be solved with the help of RabbitMQ and that is that is because it is a very powerful message broker that can help you with all the message loss challenges and ensure reliable messaging between different services.
We will look at what is RabbitMQ along with all its important core components and we will also look at how you can implement RabbitMQ in microservices.
Along with that, we will also look at all the best practices for RabbitMQ in microservices and will help you understand the importance of something like this.
So, let us understand what is RabbitMQ.
What is RabbitMQ and How Does It Work?
The simplest way to explain RabbitMQ is that it is a message broker that helps in the asynchronous communication between all the different components of a system in a microservices architecture.
This makes it quite important for microservices and it has this by following the Advanced Message Queuing Protocol (AMQP). This allows for sending and receiving messages without directly being connected to each other and that is why you do not get issues with messages.
RabbitMQ performs the function of an intermediate and allows for the storage of messages and routes them and delivers them in order to prevent message loss.
RabbitMQ can also help with retrying message sending and it is equipped to handle load balancing with efficient message distribution.
Let us now understand all the core components of RabbitMQ.
Core Components of RabbitMQ
Producer (Message Sender)
The first very important component of RabbitMQ is going to be the producer as it is the application on microservice that actually generates and sends the message to RabbitMQ.
These messages usually contain structured data in different formats in plain text as well as in other formats such as XML and JSON.
The producer acts in a different unconventional way to how we usually see message brokers work because it does not directly communicate with the consumer but sends the message to an exchange which is then adopted to the appropriate queue.
The producer works by first establishing a connection with RabbitMQ and then it publishes messages to an exchange rather than directly a queue.
After that, it is left to the exchange to determine message routing based on rules that have been already defined.
Exchange (Message Router)
We now come to the message router in the form of the exchange which is primarily responsible for making sure how and where the messages should be sent.
This means that it is going to be the component to receive the message from the producer or the message sender and it is going to route those messages to the appropriate queues.
- There are actually different types of exchanges in RabbitMQ and they can be in the form of a Direct Exchange where messages are routed based on an exact routing key match.
- Then they are Topic Exchange is where messages are routed based on different patterns.
- You also have Fanout Exchange and in this kind of exchange, you get to actually have broadcast messages and send them to all bound queues.
- And finally, you have Headers Exchange in this kind of exchange you get to route messages based on different message headers instead of routing keys.
Queue (Message Storage)
We now come to yet another important component which is the queue and this is where the messages are stored temporarily till the point they are processed by a consumer.
This is one of the best things about RabbitMQ and it is that you can expect good message durability because of the queue system as it is able to store messages temporarily with the help of persisting messages that prevent the loss of messages which usually happens if the system crashes.
Queue basically ensures message durability even if the system crashes and has to restart and it has support for multiple consumers which ensures good scalability and it also has support for First-In-First-Out (FIFO) message processing.
Consumer (Message Receiver & Processor)
And finally, we have the consumer which is an application or microservice that listens to a queue and gets the message and then processes that message and acknowledges it.
The reason why RabbitMQ is popular is simply because it has support for both push-based and pull-based consumption models and this just improves the flexibility in message processing and opens up new options.
The consumer basically works in this way. It first subscribes to a queue and then it retrieves the messages from the queue and after that, it does the processing and then sends an acknowledgement or ACK to RabbitMQ.
If no acknowledgement is received then RabbitMQ is going to try and redeliver the message and that is why RabbitMQ is preferred by developers across the industry.
Implementing RabbitMQ in Microservices
Installing RabbitMQ
Before you integrate RabbitMQ into a microservice you need to install it and in order to do that you can do it on a local machine or even deploy it within a Docker container.
We would suggest you to use a Docker container because it ultimately makes the process a lot simpler and also makes sure you maintain consistency across different environments.
If you plan on installing RabbitMQ using Docker you can run the following command:
docker run -d –name rabbitmq -p 5672:5672 -p 15672:15672 rabbitmq:management
This command will help you run the RabbitMQ container with the management plugin enabled and the port 5672 is basically used for message queuing. The port 15672 provides access to the management UI.
If you want access to the UI then you can do it at http://localhost:15672/, using the default credentials (username: guest, password: guest.
Setting Up RabbitMQ in a Microservices Environment
After you have installed RabbitMQ it is now time to set it up and because RabbitMQ acts as an intermediary message broker its setup should include different microservices so that it can produce and consume messages with RabbitMQ.
You can do that with the help of an order service producing messages as it connects to RabbitMQ and declares an exchange (orders) of type direct. It also publishes an order message with the routing key order.process.
During the setting up process, you also need to set up a consumer or inventory service which listens to a queue and processes messages.
It connects to RabbitMQ and declares a queue (order_processing) and also binds the queue to the exchange orders by using the order.process routing key and listens for messages so that they can be processed asynchronously and an acknowledgement can be sent to RabbitMQ after the processing has been completed.
Handling Fault Tolerance & Reliability in RabbitMQ
If you want to prevent message loss then you need to make both queues and messages durable. In order to make sure that queues and messages are both durable you need to modify the assertQueue function.
If you want to make the messages persistent then you need to add the persistent option when publishing messages.
Apart from that you also need to handle consumer failures and this is because if a consumer crashes without processing an image RabbitMQ should be able to send that message again and prevent message loss.
If you want to do that then the consumers should manually acknowledge the messages after they are processed.
You also need to implement a Dead Letter Exchange (DLX) in case you want to store field messages in a different queue instead of losing them. It’s options like this that allow developers to inspect problems and find solutions to them.
If you want to configure Dead Letter Queue (DLQ) you need to define it while asserting the main queue.
Scaling RabbitMQ in Microservices
RabbitMQ is excellent when it comes to scalability because it allows the option for load-balancing consumers and allows multiple consumers to process messages so that the lord is distributed evenly.
This is done by running multiple instances of consumer service.
RabbitMQ can also be deployed in a Kubernetes cluster and this just makes redundancy possible and along with that it also allows for fault tolerance and better scalability.
Key Best Practices for RabbitMG in Microservices
Use Durable Queues and Persistent Messages
One of the best practices for utilising RabbitMQ In a microservices architecture is to use durable queues and persistent messages.
This is because durable queues have the ability to survive server problems and the messages do not get lost if RabbitMQ crashes.
Persistent messages make sure that the messages do not get lost in memory and that they can be stored on the disk and this is because messages in RabbitMQ are stored in volatile memory by default but this lets you publish messages with a persistent flag so that they can be saved in the disk.
Implement Message Acknowledgments (ACKs and NACKs)
If you want to ensure that the messages are processed correctly and successfully then you do not need to worry because RabbitMQ provides an acknowledgement (ACK) mechanism that is going to allow consumers to confirm when the message has been processed.
However, if a consumer fails before the acknowledgement, then RabbitMQ will requeue the message for another consumer to process and this prevents data loss.
If you want to prevent that then you should use manual acknowledgements instead of automated acknowledgement so that you can be sure that the messages are not removed from the queue until they are completely processed.
Implement Dead Letter Exchanges (DLX) for Failed Messages
It might just so happen to be the case that some messages might still fail multiple times because of different kinds of errors or misconfigurations.
You do not have to worry about them being discarded because RabbitMQ is among the very few brokers that will allow you to route them to a Dead Letter Exchange (DLX). This allows the messages to be stored in a Dead Letter Queue (DLQ) so that they are not lost.
This is one of the most important best practices because it will simply allow you to not lose messages and this is quite an important aspect of RabbitMQ.
Secure RabbitMQ with Authentication and Encryption
The last and most important best practice you should always maintain as a developer is to make sure to pay close attention to security because security is a very important aspect of RabbitMQ.
Unauthorised access is easy and data intersection is also possible because you are dealing with messages and even message tempering can be possible.
In order to prevent things like that you need to enable authentication and authorisation as well as encryption with the help of usernames and passwords as well as enable additional levels of encryption such as Transport Layer Security (TLS) encryption.
We hope this blog has helped you understand the importance of reliable messaging in microservices with the help of RabbitMQ.
If you are looking for experienced microservices developers fluent in microservices architecture development then we are here for you.
We are Think To Share IT Solutions and we can provide you with the finest RabbitMQ implementation for your microservices architecture.
Along with that we also provide a whole host of other important IT services and solutions and we are also among the pioneering names when it comes to AI implementation solutions as well as cloud solutions.
We welcome you to our website and check out everything we do.
