Popular Message Brokers in Microservice Architecture: NATS, Kafka, and RabbitMQ

Message brokers are intermediary applications used in various software architectures, such as microservices. They transfer information in the form of messages from one service to another. A common concept associated with message brokers is the "publisher-subscriber" pattern, where events are sent from so-called "publishers" (Producers) to consumers (Consumers). Typically, an intermediary component—a message broker—participates in implementing this pattern. To simplify, let’s use an analogy. Think of YouTube: there are channels you can subscribe to for notifications. When a new video is published (an event), you’re notified because you’re subscribed. How Applications Work with Message Brokers Three main terms are relevant here: Exchange, Queue, and Binding. Exchange. This is where message events are sent. The Exchange decides which events go to which queue based on connections—bindings—which we’ll discuss shortly. Queue. The queue is a data structure that operates on a "first in, first out" (FIFO) basis. It stores data on disk or in memory, directly representing the messages. The queue provides copies of these messages to consumers. Binding. Binding refers to the set of rules that tell the Exchange which queues messages should be routed to. There can be multiple bindings with different parameters between an Exchange and a Queue. Other important terms are: Producer is a service that generates messages and sends them to the broker. Consumer is another service that begins processing it upon receiving a message. In our YouTube analogy, the "publisher" is YouTube itself, and the "consumer" is your phone, receiving push notifications. Here’s a step-by-step breakdown of how the process works: The Producer sends a message, which goes to the Exchange. The Queue stores this message, for instance, on disk. When a consumer is ready to receive a message (either because it has finished processing the previous message or the event-handling application has started), the server sends a copy of the data from the queue to the consumer. The Consumer receives the message, processes it, and then sends an acknowledgment (ACK) back to the broker. After the broker receives the acknowledgement, the message is deleted. What is RabbitMQ? RabbitMQ is a popular open-source message broker built on the AMQP (Advanced Message Queuing Protocol), an open protocol for transmitting event messages through a dedicated broker. AMQP provides a wide range of capabilities, and besides RabbitMQ, it’s implemented by other systems like Apache Qpid. RabbitMQ is written in the Erlang programming language, and its main advantages are its high throughput and maximum routing flexibility. RabbitMQ offers numerous configuration options for defining rules on which messages are sent where for processing. Connections to RabbitMQ are made over the TCP protocol: the client initiates a connection to the host address and keeps this connection open for as long as interaction with RabbitMQ is needed. RabbitMQ also supports authentication, such as login and password, for secure access. Installation on Different Operating Systems RabbitMQ consists of the server and the WebUI (admin interface). The WebUI allows you to monitor what’s happening within the broker, such as checking if the nodes in the cluster are active, seeing how many messages are in process, and more. Let’s go over how to install RabbitMQ on various operating systems. Before we begin, we need to update the server hostname. Run the command: sudo hostnamectl set-hostname <new hostname> For example, we will use rabbitmq as a hostname for this server. sudo hostnamectl set-hostname rabbitmq Install nano: sudo apt install nano And enter your new hostname in the /etc/hosts file: sudo nano /etc/hosts So it looks like this: 127.0.0.1 <new hostname> In our example: 127.0.0.1 rabbitmq Ubuntu / Debian We will be installing RabbitMQ on Ubuntu 22.04. For other Ubuntu/Debian distributions, check the guide on the official website.  Update the package list and install the dependencies: sudo apt-get update -ysudo apt-get install curl gnupg -ysudo apt-get install apt-transport-https Add repository signing keys: curl -1sLf "https://keys.openpgp.org/vks/v1/by-fingerprint/0A9AF2115F4687BD29803A206B73A36E6026DFCA" | sudo gpg --dearmor | sudo tee /usr/share/keyrings/com.rabbitmq.team.gpg > /dev/null curl -1sLf https://github.com/rabbitmq/signing-keys/releases/download/3.0/cloudsmith.rabbitmq-erlang.E495BB49CC4BBE5B.key | sudo gpg --dearmor | sudo tee /usr/share/keyrings/rabbitmq.E495BB49CC4BBE5B.gpg > /dev/null curl -1sLf https://github.com/rabbitmq/signing-keys/releases/download/3.0/cloudsmith.rabbitmq-server.9F4587F226208342.key | sudo gpg --dearmor | sudo tee /usr/share/keyrings/rabbitmq.9F4587F226208342.gpg > /dev/null Add a repository (Apt Source List) file. sudo tee /etc/apt/sources.list.d/rabbitmq.list <<EOF deb [arch=amd64 signed-by=/usr/share/keyrings/rabbitmq.E495BB49CC4BBE5B.gpg] https://ppa1.rabbitmq.com/rabbitmq/rabbitmq-erlang/deb/ubuntu jammy main deb-src [signed-by=/usr/share/keyrings/rabbitmq.E495BB49CC4BBE5B.gpg] https://ppa1.rabbitmq.com/rabbitmq/rabbitmq-erlang/deb/ubuntu jammy main deb [arch=amd64 signed-by=/usr/share/keyrings/rabbitmq.E495BB49CC4BBE5B.gpg] https://ppa2.rabbitmq.com/rabbitmq/rabbitmq-erlang/deb/ubuntu jammy main deb-src [signed-by=/usr/share/keyrings/rabbitmq.E495BB49CC4BBE5B.gpg] https://ppa2.rabbitmq.com/rabbitmq/rabbitmq-erlang/deb/ubuntu jammy main deb [arch=amd64 signed-by=/usr/share/keyrings/rabbitmq.9F4587F226208342.gpg] https://ppa1.rabbitmq.com/rabbitmq/rabbitmq-server/deb/ubuntu jammy main deb-src [signed-by=/usr/share/keyrings/rabbitmq.9F4587F226208342.gpg] https://ppa1.rabbitmq.com/rabbitmq/rabbitmq-server/deb/ubuntu jammy main deb [arch=amd64 signed-by=/usr/share/keyrings/rabbitmq.9F4587F226208342.gpg] https://ppa2.rabbitmq.com/rabbitmq/rabbitmq-server/deb/ubuntu jammy main deb-src [signed-by=/usr/share/keyrings/rabbitmq.9F4587F226208342.gpg] https://ppa2.rabbitmq.com/rabbitmq/rabbitmq-server/deb/ubuntu jammy main EOF Update the package list yet again: sudo apt-get update -y Install Erlang: sudo apt-get install -y erlang-base \ erlang-asn1 erlang-crypto erlang-eldap erlang-ftp erlang-inets \ erlang-mnesia erlang-os-mon erlang-parsetools erlang-public-key \ erlang-runtime-tools erlang-snmp erlang-ssl \ erlang-syntax-tools erlang-tftp erlang-tools erlang-xmerl Finally, install RabbitMQ: sudo apt-get install rabbitmq-server -y --fix-missing After installation is complete, you can check that rabbitmq-server is up and running: systemctl status rabbitmq-server Create a custom user: sudo rabbitmqctl add_user <your username> <your password> And give the necessary permissions: sudo rabbitmqctl set_user_tags  <your username> administratorsudo rabbitmqctl set_permissions -p /  <your username> ".*" ".*" ".*" Now you can enable RabbitMQ Management Console: sudo rabbitmq-plugins enable rabbitmq_management And visit <your server IP>:15672. Enter your username and password and access the RabbitMQ web UI. Windows You can find the installation guide on the RabbitMQ website. Basically, you can either use Chocolatey or a simple installer.  However, before installing RabbitMQ, we first need to install Erlang/OTP from the official Erlang website. Run the downloaded file and go through the installation process. After installing Erlang, we can install RabbitMQ, for example, using the installer from the official website. Next, let's enable the WebUI: cd 'C:\Program Files\RabbitMQ Server\rabbitmq_server-3.13.0\sbin'./rabbitmq-plugins.bat enable rabbitmq_management Now, you can visit localhost:15672 and access the RabbitMQ web UI using the default username and password guest:guest. Docker Installing via Docker is probably the simplest and most convenient way to install RabbitMQ.  We can install RabbitMQ using the following docker run command: docker run --rm -p 15672:15672 rabbitmq:3.13.7-management The admin interface will be available on port 15672, where you can log in with the default username and password guest:guest. However, this method of running RabbitMQ is not suitable for a production environment. Docker assigns a server name to the container, and the message broker stores its state in a folder with that name. With every new container build, RabbitMQ will lose its state information. We can conveniently define all necessary service parameters with docker-compose, such as changing the default login and password, mounting a folder for state persistence, etc. Here's an example of what the docker-compose.yml file might look like (this can be created on your server where Docker is installed or on your local machine). version: "3.3" services: rabbit: image: rabbitmq:3.13.7-management environment: - RABBITMQ_DEFAULT_USER=admin #enter your username - RABBITMQ_DEFAULT_PASS=password #enter your password volumes: - ./rabbit:/var/lib/rabbitmq # mounting folder for state persistence ports: - 15672:15672 # expose port for the admin interface Run: docker compose up -d The RabbitMQ web UI is now available. Overview of RabbitMQ Management Let's take a look at the main features of the RabbitMQ management interface. On the main page, you can view general information such as nodes, their status, total message count, and more. Connections  is the list of connections to the cluster. Channels is the list of channels. Multiple channels can be created within a single connection through which messages are sent. This is done to avoid creating multiple TCP connections. Exchanges Let’s look more closely at Exchanges. There are different types of exchanges, each with its own message filtering mechanism. Based on these rules, events are routed to specific queues. Direct Exchange Each message has a key, called the Routing Key. These messages will be routed to queues where the binding to the Exchange specifies the same key. Topic Exchange Routing is done based on a pattern key. When creating the pattern, you can use 0 or more words (Latin letters in different cases and numbers) separated by dots (e.g., "key.event"), and the symbols # and *. Fanout Exchange No filtering rules are applied. Every message sent to a Fanout Exchange is routed to all queues. Headers Exchange Uses message headers and binding headers, comparing key-value pairs in those headers. Queues When viewing a specific queue, you can see a graph showing how many messages are in the queue, statistics about delivery times, and message acceptance times. Messages can have two statuses: Ready – waiting to be processed. Unacked – being processed by the consumer. Implementing Publisher-Subscriber in Python Let’s go through how to use RabbitMQ to implement the Pub-Sub pattern in Python. You should have Python installed on your system. This tutorial uses version 3.11.5 of Python. We will be using the Pika library.  Create or select a folder where the application code will reside. For example: mkdir rabbitmq-article Open this folder in your IDE. It can be Visual Studio Code, PyCharm, or other development environments. Install the Pika library by running the following command in the terminal: pip install pika Now, let's create two files: sender.py and receiver.py. sender.py code from pika import BlockingConnection, ConnectionParameters from pika.exchange_type import ExchangeType # Create connection, specifying parameters in the ConnectionParameters object connection = BlockingConnection(ConnectionParameters(host='localhost')) # Create a channel channel = connection.channel() # Declare an exchange channel.exchange_declare('new_exchange', ExchangeType.direct) # Declare a queue queue = channel.queue_declare(queue='new_queue') # Bind the queue to the exchange channel.queue_bind(exchange='new_exchange', queue='new_queue', routing_key='key') # Publish a message channel.basic_publish(exchange='new_exchange', routing_key='key', body='Hello World!') print("Message 'Hello World!' sent") connection.close() In the above sender.py code: We establish a connection to RabbitMQ on localhost. We declare a direct exchange called new_exchange. We declare a queue called new_queue. We bind the queue to the exchange using a routing key key. Finally, we publish the message 'Hello World!' to the exchange with the specified routing key. Now, let's implement the receiver.py to consume the message. receiver.py code from pika import BlockingConnection, ConnectionParameters from pika.exchange_type import ExchangeType import sys, os def main(): # Create connection connection = BlockingConnection(ConnectionParameters(host='localhost')) # Create channel channel = connection.channel() # Declare an exchange channel.exchange_declare('new_exchange', ExchangeType.direct) # Declare a queue queue = channel.queue_declare(queue='new_queue') # Bind the queue to the exchange channel.queue_bind(exchange='new_exchange', queue='new_queue', routing_key='key') # Function to handle incoming messages def handle(ch, method, properties, body): print(f"Received message: {body.decode()}") # Bind the callback function and queue channel.basic_consume(queue='new_queue', on_message_callback=handle, auto_ack=True) print('Waiting for messages. Press Ctrl+C to exit.') channel.start_consuming() if __name__ == '__main__': try: main() except KeyboardInterrupt: try: sys.exit(0) except SystemExit: os._exit(0) In the above receiver.py code: We establish a connection and channel to RabbitMQ, just as we did in the sender. We declare the direct exchange (new_exchange) and queue (new_queue). The queue is bound to the exchange using the routing key key. The handle function processes the message by printing it when received. The basic_consume method subscribes the callback function to the queue. We use start_consuming to keep the process waiting for messages indefinitely. Running the Code Start the receiver first. Open a terminal and run receiver.py: python receiver.py You should see the message: Waiting for messages. Press Ctrl+C to exit. Now, run the sender. Open a second terminal and run sender.py: python sender.py You should see the message: Message 'Hello World!' sent In the terminal where the receiver is running, you will see: Received message: Hello World! In RabbitMQ Management, you can go to the created exchange (new_exchange) and see that it is bound to the queue (new_queue) using the routing key (key). Conclusion In this article, we explored what message brokers are, how applications interact with them, and how to install and use RabbitMQ as a message broker. We successfully implemented a Publisher-Subscriber pattern using Python, RabbitMQ, and the Pika library, where the sender publishes messages to an exchange and the receiver consumes them.

The term "microservices" has become quite common in today's tech world. But what does it really mean, what advantages can it bring to your business, and is it worth moving from the time-tested monolithic architecture to this new approach? We'll try to answer all these questions in this article. What is Monolithic Architecture? Monolithic architecture is a software development approach where all functional components (services, managed databases, user interfaces, etc.) are combined into one structure or system. In such a structure, all elements interact with each other and operate as a single mechanism. Schematically, a monolith can be imagined as a large box containing all the elements of the application. Key Features of Monolithic Architecture Unified Deployment: All components of monolithic architecture are assembled and deployed as a single entity. Even if you need to change a small part of the application, you must modify the entire codebase and then redeploy the whole application. Shared Resources: All components of the application use common resources, such as shared storage, shared memory, and shared network. In-Process Communication: Components interact directly with each other through internal communication mechanisms (direct function and method calls) without requiring external interfaces and protocols. A practical example of monolithic architecture might be a traditional web application, like an online store. In this case, the entire functionality of the site, including displaying the product catalog, processing orders, and managing user interfaces, is usually implemented as a single application. This application is developed, tested, and deployed as a unified product. Advantages of Monoliths Simplicity of Deployment: Monoliths simplify the deployment and update process since all components are combined into one process and can be deployed on a single server or online. Avoiding the Complexities of Distributed Systems: In monolithic systems, there are no delays or unavailability issues related to using separate services or databases. Simplified Development Processes: Thanks to centralized code and a unified technology stack, development in a monolithic system is usually more orderly and consistent, promoting efficiency and performance. Easier Monitoring and Troubleshooting: Monolithic systems make identifying and resolving issues easier since all code is in one place, and testing can be done within a single system. Simplified End-to-End Testing: It is easier to track how data and requests move through different parts of the application in monoliths, facilitating end-to-end testing. Basic Simplicity: All elements of the monolithic system are in one place, simplifying code search, usage, and modification. Disadvantages of Monoliths High Coupling: In a monolith, all functions and components are tightly connected, sometimes leading to situations where changing or updating one component causes unexpected issues in other parts of the system due to the high degree of interdependence. Challenges in Scaling the Team: Conflicts of interest can arise when many people work on the same system simultaneously. Developers may want to change the same code, and different teams might have different plans and deployment schedules. Code Ownership Conflicts: When several developers or teams work on the same module or functionality of the software, issues can arise. For example, different teams' different approaches to coding or designing functionality can lead to inconsistencies in code style or application structure. Competition for Delivery: When different teams simultaneously change different parts of the monolith, coordination problems, lack of uniformity in code and project management, conflicts of interest, and unproductive competition can occur. What is Microservices Architecture? Unlike monolithic architecture, microservices consist of small independent services, each solving specific tasks within a larger business context. Each service handles its domain and offers its capabilities to other services via the network, creating a more complex system from smaller parts. Key Features of Microservices Architecture Separation into Independent Services: Each microservice serves a specific function and can be developed in its environment. For example, one microservice might manage warehouse inventory, another handles orders, and a third manages delivery, but together, they can support a complete online sales system. Independent Deployment and Scaling: Microservices can be deployed, updated, and scaled independently of each other. This means that if you need to change one part of the system or if the load on a specific service increases, you can make changes only to that service without affecting the others. Distributed Data Management: In microservices, each service has its database, which it uses to operate. This helps avoid issues with shared data access and allows more efficient information management. Freedom of Technology Choice: Since each microservice is developed separately, developers can choose technologies and programming languages they find most suitable for specific tasks rather than being tied to one technology for the entire project. Microservices are an excellent way to manage the development of large and complex applications. They allow for more flexible system configuration to meet specific needs, speed up development, and simplify scaling. However, they also introduce new complexities, such as coordination between services, security, and data management. Advantages of Microservices Modularity: Large, complex systems are broken down into smaller, manageable parts. These modules can be developed, tested, and deployed independently. Adding New Features: When you need to add a new feature to your application, you can simply create a new microservice. This significantly simplifies development since you don't have to modify and test the entire system—only the new service. Removing or Replacing Services: If some aspects of the application become obsolete, you can easily remove the corresponding microservices. Similarly, if you want to update a part of the application, you can simply replace the old microservice with a new one. Reusability: Individual services can be designed to be reused across different applications, leading to significant time and effort savings. Overall, modularity creates a simpler, more intuitive, and manageable system structure. Scalability: Unlike monolithic systems, where increasing the performance of one component requires scaling the entire application, which can be costly and inefficient, microservices allow focusing efforts on specific segments that need increased capacity. For example, if one service experiences a sudden increase in load, there's no need to scale the entire functionality—just increase the capacity of that specific service. This leads to significant resource savings and overall efficiency for many companies. Independence of Development Teams: Microservices provide a high level of independence for development teams working on different aspects of the system. Each team can develop, test, and deploy its services independently of other teams. Freedom of Technology Choice: Each team can choose the technologies that best suit the specific tasks of their microservice. There's no need to coordinate the choice of programming languages, development tools, or databases with other teams. Each microservice can be written in its programming language and use its database if necessary. Quick Implementation of Changes: Since each microservice is developed independently, changes can be implemented quickly, without waiting for other teams to finish their work. This can significantly speed up the product's time to market and enable faster responses to changing requirements or market conditions. More Efficient Use of Resources: When each team specializes in a specific microservice, they can dedicate more time to perfecting that service rather than coordinating with other teams. Faster Integration and Update Processes: In traditional monolithic architecture systems, any changes or updates require recompiling and restarting the entire system. However, with a microservices architecture, each service can be deployed and updated independently of the other components. When changes or new functionality are ready in one of the services, there's no need to wait for the completion of work on other parts of the application—the update applies only to the specific microservice. This approach reduces the time between releases and also lowers the risks associated with updates, as in case of a problem, only one microservice is affected, not the entire system. Simplified Debugging and Maintenance Process: Microservices architecture significantly eases maintenance and diagnostics tasks. In a monolithic system, a malfunction can impact the entire system, making it difficult to identify and fix the defect. In a microservices architecture, potential issues typically affect only one service, allowing for quick localization and resolution of the problem without impacting other system components. Moreover, each service can be monitored and logged independently, providing greater transparency into the behavior of each service. This simplifies the process of troubleshooting and fixing issues. Disadvantages of Microservices Technological Complexity One of the challenges developers often face when transitioning to a microservices architecture is the technological complexity. Microservices typically involve using more complex and diverse technologies compared to monolithic architecture. Each microservice may use different programming languages, databases, and tools, requiring the team to broaden their knowledge and skills in these areas. Additionally, each microservice will need its own infrastructure and tools for monitoring, testing, and deployment, which can significantly complicate the development and maintenance process. It's important to understand that this not only increases the complexity of the tech stack but also affects the speed and efficiency of work. This can lead to longer development times and slower release cycles. Coordination Complexity In a microservices architecture, each service must interact successfully with others to ensure the system's full functionality. This interaction needs to be precise and coordinated, which can sometimes be a challenging task. Cost Developing microservices can require larger initial investments compared to monolithic architecture, especially if the team needs training in new technologies. Additionally, more robust networks and data storage systems may be needed to handle the increased volume of interactions between services. Microservices may also demand more complex and costly maintenance, as each service needs to be monitored and supported individually. Continuous monitoring and optimization of microservices can be labor-intensive and potentially expensive. Testing Testing in microservices architecture presents its own unique challenges. The broader the scope of testing, the greater the confidence in the system's performance and stability. However, broad testing coverage means increased complexity in setting up test data and auxiliary tools, longer test execution times, and difficulty identifying the source of a failure if it occurs. As the microservices architecture grows, the volume of testing can become significant. Tests may become so extensive that they need to be run across multiple processes, each of which must be properly deployed and configured. There's also a higher risk of false positives in tests due to hardware failures, service instance failures, network delays, or other issues with the deployment environment. Security In a monolithic system, all data and functionality are handled within a single process, making data transfer and communication relatively secure. However, when moving from a monolith to microservices, more data is transmitted over the network, increasing the risk of data leaks or cyberattacks. The risk of a "man-in-the-middle" attack, where an attacker intercepts and potentially alters information exchanged between two parties, also increases. Should You Transition from a Monolith to Microservices? Today, transitioning to microservices has almost become a trend in the IT world. But it's important to understand that moving to a microservices architecture isn't a matter of following trends. It should be a well-considered decision aimed at achieving specific goals that your current architecture cannot fulfill. It's crucial to ask yourself, "What do we want to achieve by transitioning to microservices?" Without a clear understanding of the goals and benefits of such a transition, it can become a source of unexpected problems and additional costs. Of course, in this article, we can't know or understand your company's unique tasks and goals. Nevertheless, we can discuss when using microservices brings the greatest benefits. Why Choose Microservices? Increased Autonomy Projects based on microservices architecture allow teams to work on different parts of the system independently from each other, enabling them to handle tasks faster and more efficiently. Each team focuses on a specific service and tailors its work process to meet the specific requirements of that service. For example, take a large web service for online shopping. One team might work on the product catalog service using Ruby, another on payment processing using Python, and yet another on tracking deliveries using Java. Each team chooses its own methodologies and technologies, sets its work schedule, and manages its resources without affecting other teams or the overall system. Faster Time to Market The efficiency of microservices lies in breaking down your application into many independent components that can be developed and tested separately. This means you are no longer tied to lengthy, complex release coordination processes. Instead, you can choose a specific improvement or new functionality and quickly implement it without affecting the rest of the system. Imagine you have a ticket-selling application and want to add a "recommendations" feature. In a monolithic architecture, you'd likely have to wait for the next major update to implement this feature, which could take months. However, in a microservices architecture, you can create a new microservice for this feature and release it much faster. Cost-Effective Scaling Scaling is another area where microservices show their advantages. The uniqueness of microservices lies in the ability to scale each one individually according to current needs. This allows for more flexible resource management and cost control. For example, you have a microservice responsible for payment processing. During a sale, the number of transactions sharply increases, requiring more resources from the microservice. Instead of scaling the entire system at a great cost, you can simply increase the capacity of this specific microservice. This also works the other way; if you have a microservice handling newsletter subscriptions with low demand, you can reduce its capacity, thus gaining more control over operational costs. Increased System Resilience Stability and resilience to unexpected failures or errors are crucial for the successful operation of any system, and microservices play an important role in this context. The resilience of microservices is based on the principle of independence. If one microservice encounters a problem or failure, it won't affect the operation of other services. In contrast, in monolithic architecture, an error in one part of the code can cause the entire application to crash. For instance, in an online store divided into multiple microservices responsible for different functions—shopping cart, product catalog, payment processing, etc.—if the cart service fails due to a technical issue, customers can still browse products, search for information, or even make purchases directly. All other functions of your online store will continue to work normally. Adoption of New Technologies Monoliths typically impose significant limitations on technology choices. With a microservices architecture, the options for each service are more diverse. Introducing a new technology is confined to the boundaries of a single service, allowing you to test the benefits of the new technology without affecting other services, and limit the negative impact if challenges arise. Imagine a web service that tracks the weather in specific locations. Initially, the entire service is written in Java, but then you decide to introduce Python for statistical data processing because it has convenient tools. Thanks to microservices, Python can be implemented only in the service responsible for processing statistical data without affecting the operation of other services, which will continue to function as usual. When Are Microservices a Bad Idea? Unclear Domain In the context of microservices, a "domain" refers to the part of the business process that a specific microservice serves. Creating a separate microservice can be a bad idea if this area is not clearly and correctly defined. Imagine a company using microservices where the domain of each service is not clearly defined. This could lead to situations where different services perform similar or even redundant functions or, conversely, where necessary functions are left unaddressed. This is inefficient and increases the complexity of interactions between services. Another issue is the incorrect understanding of service boundaries. If the boundaries between services are unclear and improperly defined, it can lead to cross-dependencies and difficulties coordinating service operations. This results in additional maintenance and development costs, as well as errors and confusion in the system. If you realize that you don't yet fully understand your domain, it's better to address this issue before breaking down your monolithic application into microservices. Startups  There is some debate about the use of microservices in startups. Many well-known companies that actively use microservices today transitioned to them only after achieving a certain level of success and growth. A startup, by definition, is a small organization with limited resources striving to find a viable business model for its product in the market. This task requires flexibility and the ability to adapt to market feedback quickly. In this situation, microservices may not be the optimal choice due to the complexity of their implementation and maintenance. Microservices are an excellent solution to problems that arise when a successful startup grows, requiring efficient scaling, complexity management, and ongoing development. However, if the initial idea does not yield the desired results, it doesn't matter whether microservices were used or not. Transitioning to microservices should only be done when domain boundaries and their interactions are clear and stable. Client-Side Management and Maintenance If your company develops software intended for clients to manage on their own, using microservices can create problems. Setting up and configuring microservices requires a certain level of technical expertise. If your clients lack the necessary skills and knowledge, they may struggle to deploy and configure each microservice. Moreover, microservices generally require more computing resources compared to monolithic applications. If your clients work with limited resources, they might face challenges in running and managing microservices. Therefore, a monolithic architecture is often preferable if the software is intended to be installed on the client side. Lack of Clear Understanding of the Purpose for Transitioning The decision about monolithic vs microservices should be deliberate and based on specific business requirements and goals. If you find it difficult to answer the question, "Why do we need this?", then it's probably too early to move to a microservices architecture. The decision to transition to microservices should consider the specifics of your business and technical requirements. The transition may require significant time and resources for staff training and developing and maintaining new processes and tools. Conclusion In this article, we've explored the advantages and disadvantages of both traditional monolithic architectures and modern microservices approaches while trying to answer the question: "Should you transition from a monolith to microservices?" Microservices attract attention with their incredible flexibility. They offer a wide range of technologies, improved reliability, and scalability. This flexibility is one of the reasons for their growing popularity. However, transitioning to microservices comes with its own challenges. Yes, they are suitable for many situations, but their use involves significant costs, and before making a decision, it's essential to carefully assess whether these costs will be justified. Many choose microservices architecture by default, assuming it suits any project. However, it's important to remember that sometimes simpler solutions can more effectively achieve your goals. If approached wisely, microservices can become more than just the sum of separate system parts. This is where their true potential lies.