Advantages of Microservices Architecture: Should You Transition from a Monolith to Microservices?

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.