Microservices architecture: is it right for your next project?

The decision to choose the right software architecture is one of the most important and fundamental steps in the early stages of any development project. It has far-reaching consequences for scalability, maintainability, speed of development, resilience to failures and total cost of ownership of the system. For many years, the dominant approach was a monolithic architecture, in which all application components are tightly coupled and form a single, cohesive deployment unit. However, in recent years, with the increasing complexity of systems, the development of cloud technologies and the need for greater agility, microservices architecture has become increasingly popular. It involves building applications as a collection of small, independent and autonomous services, each of which performs a specific business function and can be developed, deployed and scaled independently of the others. However, choosing between these two, and other hybrid approaches, is not easy, and there is no universal “silver bullet.” For IT principals and architects, it is crucial to have a thorough understanding of both the advantages and disadvantages of each of these models, and to be able to assess which one best suits the specific requirements and context of a given project and the organization’s long-term technology strategy. This article aims to provide a detailed comparative analysis of monolithic and microservices architectures, providing a decision framework and practical guidance to help make an informed and optimal decision.

Monolithic architecture, often referred to simply as “monolith,” is a traditional model for building an application in which all of its functional components – such as user interface (UI), business logic, data access layer, integration modules – are tightly interconnected and constitute a single, indivisible unit of code, compiled and deployed as a single artifact (e.g. .war, .jar, .exe file). Although internally the monolith may be divided into logical modules or layers, from an implementation and operational perspective it is treated as a whole. For many years this has been the dominant approach in software development, and many critical business systems still in operation are based on this architecture.

Monolithic architecture has a number of advantages that can still make it an attractive choice in certain situations. First of all, in the early stages of project development, especially for smaller applications or when building a Minimum Viable Product (MVP), a monolith is usually simpler and faster to design, build and deploy. All components are in one place, making it easier to manage the code (e.g., in a single repository), the build process and the configuration of the development environment. Communication between components inside a monolith is usually very fast and efficient, as it is done through direct function or method calls within the same process, without the overhead associated with network communication that occurs in distributed systems. End-to-end testing of a monolithic application tends to be simpler initially, since all parts of the application are available in a single environment. Managing a single point of deployment and monitoring can also be seen as an advantage, especially for smaller operations teams. Often the initial cost of building a small or medium-sized project in a monolithic architecture is lower than for more complex distributed architectures.

However, as the size and complexity of the application increases, the monolithic architecture begins to reveal its significant drawbacks and limitations. One of the biggest problems is the difficulty of scaling individual system components. If only one module of the application requires more computing power or bandwidth, the monolith requires scaling the entire application, which is cost and resource inefficient. Long build time (build time) and deployment time (deployment time) become more acute as the code base grows. Even a small change to a single module can require rebuilding and re-deploying an entire, large application, which slows down the development cycle and increases the risk associated with each deployment.

A monolithic architecture also carries the risk of a “single point of failure” (single point of failure). A bug in one module, even a less critical one, can lead to instability or complete failure of the entire application, affecting all its functionalities. Implementing new technologies and frameworks in an existing monolith can be very difficult and risky. The entire application is usually built on one technology stack, and trying to introduce components based on another technology can be complicated and lead to compatibility issues. Over time, as new functionality is added and numerous modifications are made, the increasing complexity of the code and the mounting technical debt become more of a problem. Code becomes difficult to understand, maintain and modify, and the risk of introducing regressions with each change increases. The problems of maintaining and developing large, aging monoliths are well known to many organizations. Finally, the “snowball effect” in the occurrence of bugs means that problems in one part of the system can easily propagate to other parts, making them difficult to diagnose and isolate.

Despite these limitations, a monolithic architecture can still be a good or at least sufficient choice in certain situations. This is especially true for small, simple projects or applications with limited functionality, where the benefits of more complex architectures would not offset the added complexity. It can also be a good approach at the Minimum Viable Product (MVP) stage of development, when the priority is to quickly test an idea in the market, and scalability and operational complexity are not yet key concerns. For development teams with less experience in designing and managing distributed systems, starting with a simpler monolithic architecture may be a safer option, allowing them to gain experience before possibly moving to more complex models.

Microservices architecture – a revolution in building complex systems

In response to the limitations and challenges of monolithic architecture, especially in the context of building large, complex and dynamically evolving systems, microservices architecture was born and has gained enormous popularity. It is an approach to designing and building applications as a collection of small, independent, autonomous and loosely coupled services (services), each of which performs a precisely defined, narrow business or technical function.

The key principles and features of the microservices architecture are:

• Small size and focus on a single responsibility (Single Responsibility Principle): Each microservice is relatively small and focused on performing one well-defined task or piece of business logic.
• Independence and autonomy: Microservices are designed, developed, tested, deployed and scaled independently of each other. The failure of one service should not (ideally) lead to the failure of the entire system, but only to the unavailability of a specific functionality.
• Communication through well-defined APIs: Microservices communicate with each other using lightweight, standard protocols (most commonly HTTP/REST, gRPC or message queues) through clearly defined and versioned APIs.
• Decentralization of data management: Each microservice may (but need not) have its own dedicated database or data schema, optimized for its specific needs. This allows greater flexibility in the choice of data storage technology and avoids the problems associated with a single, central database.
• Ability to use different technologies for different services (Polyglot Programming and Persistence): Because microservices are independent, each can be implemented using the technology (programming language, framework, database) that is best suited to its specific requirements, without imposing a single, common technology stack for the entire system.
• Organizing teams around business capabilities (Conway’s Law): A microservices architecture often goes hand in hand with the organization of development teams around specific business functionalities or product domains, where each team is fully responsible for the lifecycle of “its” microservices.

The main advantages of microservices architecture are a direct response to the limitations of monoliths. First of all, it offers much better scalability and flexibility. Individual microservices can be scaled independently of each other, depending on their individual workloads, allowing for more efficient use of resources. The technological independence of individual services gives great freedom in choosing the best tools for specific tasks and facilitates the gradual introduction of new technologies into the system. The process of deploying and updating individual components becomes much faster and less risky, since a change in one microservice does not require rebuilding and re-deploying the entire system. Development cycles can be shorter and deployment frequency higher. The microservices architecture also provides greater fault tolerance – if one less critical service fails, the other parts of the system can continue to function (graceful degradation). It also allows multiple independent, smaller development teams to work on individual services, which can speed up development and increase ownership.

However, the move to a microservices architecture also comes with significant challenges and increased complexity, especially operationally. Managing multiple independent, distributed services is much more complicated than managing a single monolith. There are challenges associated with monitoring, logging and debugging in a distributed system, where a single user transaction may pass through many different services. Communication overhead between services (latency, network reliability) becomes an important factor to consider in design. Ensuring data consistency between services, which often have their own databases, requires advanced patterns, such as domain events and saga patterns. Microservices architecture also requires mature DevOps practices for automating build, test, deployment and monitoring. The upfront costs of building the infrastructure and tools to support microservices can be higher than for a monolith, and development and operations teams need to have the appropriate, often more advanced competencies in designing and managing distributed systems.

Monolith vs. microservices – detailed comparison and selection criteria for your project

The decision to choose between monolithic architecture and microservices should be preceded by a careful analysis of the project’s specific requirements, business context, available resources and long-term vision for system development. There are no simple rules here, and what works in one case may be completely inappropriate in another. Below is a comparison of the two approaches in terms of key criteria that can help in making this strategic decision.

Scalability: microservices offer much greater granularity and flexibility for scaling. Individual services can be scaled independently in response to their individual workloads (e.g., by increasing the number of instances of a given service). A monolith is typically scaled as a whole (scaling horizontally by running multiple instances of the entire monolith, or scaling vertically by increasing server resources), which is less efficient if only some parts of it require more power. Winner: microservices.

Flexibility and speed of development: With microservices, smaller, independent teams can work on different services in parallel, and changes to one service do not directly affect others (as long as the API remains stable). This allows for faster development cycles, more frequent deployments and greater agility in responding to business needs. In large monoliths, making changes can be more complicated and time-consuming, and the risk of regression is higher. Winner: microservices (especially for large systems).

Fault tolerance and fault isolation: A well-designed microservices architecture is more resilient to failures. A problem in one service does not necessarily lead to the failure of the entire system – other services can continue to work, and the system may only suffer partial degradation. In a monolith, a bug in one component often makes the entire application unstable. Winner: microservices.

Technological and operational complexity: Monolithic architecture is generally simpler technologically and operationally, especially at the beginning of a project and for smaller systems. A microservices architecture introduces significant complexity associated with managing a distributed system – communication between services, service discovery, monitoring, logging, debugging, ensuring data integrity. This requires more advanced tools and competencies. Winner: the Monolith (especially in terms of initial complexity).

Costs (initial, maintenance, development): Initial costs for building a simple monolith are usually lower. However, as the monolith grows, the cost of maintaining and further developing it can rise sharply due to increasing complexity and technical debt. Microservices may involve higher initial costs (infrastructure, tools, competencies), but in the long term, for large and complex systems, they may offer better cost efficiency due to the ability to scale independently, optimize resources and maintain individual components more easily. Cost assessment is highly dependent on the specific case. No clear winner – depends on the scale and stage of the project.

Team competency requirements: Building and managing a microservices architecture requires the development and operations team to have much broader and deeper competencies in distributed systems design, cloud technologies, containerization, automation (DevOps), monitoring and complexity management. A team working on a monolith may have a slightly lower threshold for entry, although solid engineering knowledge is required here as well. Winner (in terms of lower initial requirements): Monolith.

Ability to use different technologies: A microservices architecture gives you complete freedom to choose the technologies (programming languages, databases, frameworks) best suited to the specific needs of each service (polyglot approach). In a monolith, the entire system is usually based on a single, consistent technology stack. Winner: microservices.

Ease of testing: Testing individual microservices in isolation is usually simpler and faster. However, integration and end-to-end testing in a distributed system consisting of multiple microservices can sometimes be much more complicated than in a monolith, where all components are available in a single process. Winner (for unit and component tests): Microservices. Winner (for initial end-to-end testing): Monolith.

Security: Both monolith and microservices have their security challenges. In a monolith, a security breach at a single point can potentially compromise the entire application. In microservices, the attack surface is larger (more entry points – each service’s API, network communication), but at the same time it is possible to better isolate individual services and apply more granular security policies. However, security management in a distributed system requires additional mechanisms (e.g. authentication and authorization between services, secure API gateways). No clear winner – depends on the implementation.

Data management: In a monolith, there is usually one central database, which makes it easier to ensure data consistency and execute transactions involving multiple modules. In a microservices architecture, where each service may have its own database, ensuring data consistency in a distributed system (eventual consistency, sagas) is much more challenging and requires advanced patterns. Winner (in terms of simplicity of data integrity management): Monolith.

When is it definitely worth considering microservices? When building a large, complex system to be developed over many years and by many independent teams. When high scalability of individual components and fault tolerance are crucial. When we want to be able to use different technologies for different parts of the system and rapidly deploy new functionality. When the organization has mature DevOps practices and the right competencies in the team.

When might a monolith be a better or sufficient choice? For small and medium-sized projects, especially early stage projects (MVPs). When the team is small and has no experience in distributed systems. When priority is given to speed of first release deployment and operational simplicity. When we don’t anticipate rapid scale-up or the need for very granular scaling.

It’s also worth remembering that it doesn’t always have to be a zero-sum choice. There are hybrid approaches, such as a well-designed modular monolith, which combines the advantages of the simplicity of a monolith with some modularity and the possibility of later, incremental separation of individual modules as microservices. The approach of starting a project with a well-structured monolith and then, as complexity and needs increase, gradually moving to a microservices architecture (the so-called “start with a monolith, then refactor to microservices”) is also becoming increasingly popular.

Key success factors for implementing microservices architecture

If an organization decides to implement a microservices architecture, there are a number of key factors that are fundamental to its success. Simply dividing an application into smaller services is not enough – a holistic, strategic approach is needed.

It is critical to have a mature DevOps culture in the organization and a high degree of automation of all stages of the software development lifecycle – from build and test (Continuous Integration) to deployment (Continuous Delivery/Deployment) to infrastructure monitoring and management (Infrastructure as Code). Without a solid DevOps foundation, managing multiple independent microservices will quickly become an operational nightmare.

Microservices architecture requires design for failure. In a distributed system, failures of individual services or network communication problems are inevitable. Therefore, each microservice should be designed in such a way that it can withstand the failure of its dependencies (e.g. by using mechanisms such as circuit breakers, retries, timeouts) and that its eventual unavailability does not lead to the paralysis of the entire system.

It is essential to implement effective monitoring, logging and distributed tracing mechanisms. Understanding what is going on in a system consisting of dozens or hundreds of microservices requires advanced tools to collect and correlate logs from different sources, track individual requests passing through multiple services, and monitor key performance and availability metrics for each service.

It is also necessary to implement solutions for configuration management of individual services and service discovery mechanisms that allow to dynamically locate and communicate with instances of individual microservices in a flexible, frequently changing environment.

Security in a microservices architecture is another major challenge. Adequate authentication and authorization mechanisms must be taken care of, both for end users and for communication between different services. Security of APIs, protection against typical attacks on web applications and management of secrets and sensitive data in a distributed environment require special attention.

Finally, it is crucial to apply appropriate strategies for partitioning the system into microservices. There are no golden rules here, but popular approaches are based on Domain-Driven Design (DDD) principles and the concept of bounded contexts, which allow services to be partitioned around consistent areas of business functionality. Improper separation (e.g., services that are too small or too large, incorrectly defined boundaries between them) can lead to problems with performance, data consistency and communication complexity.

ARDURA Consulting – expertise in designing and implementing optimal software architectures

Choosing and implementing the right software architecture is one of the most important technology decisions that will have a long-term impact on the growth of your business. At ARDURA Consulting, we have years of experience and deep expertise in designing, building and transforming software systems based on both proven monolithic architectures and modern, scalable microservices architectures and hybrid approaches.

Our experienced architects and consultants help clients conduct an in-depth analysis of their business needs, technology requirements, existing system landscape and long-term development strategy. On this basis, we work together to develop recommendations for selecting the most optimal architecture for a given project or system, taking into account all key factors – from scalability and performance, to cost and risk, to available competencies and organizational culture.

At ARDURA Consulting, we do not advocate a one-size-fits-all approach. We understand that both a well-designed monolith and a carefully implemented microservices architecture can be effective solutions when properly tailored to the context. Our goal is always to find the golden mean and propose an architecture that best suits each client’s unique needs and strategic goals.

We offer comprehensive support at every stage of the software development lifecycle – from architecture design and technology selection, through application construction and development (both monolithic and microservices-based systems), to transformation and modernization of existing legacy systems, e.g. through gradual transition from monolith to microservices. We place particular emphasis on the quality, security, performance and maintainability of the solutions we develop, applying software engineering best practices and modern project management methodologies (including Agile and DevOps). Our approach is based on the synergy of strategic consulting and high-quality implementation, which allows us to deliver solutions that not only work, but also realistically support our clients’ business growth.

Conclusion: Choosing an architecture is a strategic decision – there is no silver bullet

The decision between monolithic architecture and microservices (or one of the hybrid approaches) is one of the most important and fundamental decisions that architects and technology leaders must make at the beginning of any software project. There are no simple answers or one-size-fits-all solutions that will work in every situation. Each approach has its own unique advantages, disadvantages and areas of optimal application. The key to success is an in-depth understanding of the specifics of your own project, its business goals, non-functional requirements, available resources and competencies, and the long-term vision for system development. An informed choice of architecture, based on sound analysis and realistic assessment of all factors, is the foundation for building systems that will not only be efficient and reliable, but also capable of evolving and adapting in the rapidly changing world of technology and business.

Summary: Monolith or microservices – which to choose for your project?

Choosing the right software architecture is a crucial decision. Here are some questions and criteria to help you decide between monolithic and microservices:

• What is the scale and complexity of your project?
  • Monolith: Often better for small, simple applications, MVP when the team is small.
  • Microservices: Worth considering for large, complex systems that are expected to grow and evolve.
• What are your scalability requirements?
  • Monolith: Scaled as a whole; less effective if only part of the system needs to be scaled.
  • Microservices: Enable independent scaling of individual services, which is more resource-efficient.
• How important is speed of development and independence of teams?
  • Monolith: Changes can be slower in large systems; one team often works on the whole.
  • Microservices: Enable multiple independent teams to work on different services, which can speed up development and deployment.
• What is your tolerance for operational complexity and what is your DevOps competency?
  • Monolith: Generally simpler to manage operationally at first.
  • Microservices: Introduce significant operational complexity (distributed system), require mature DevOps practices and appropriate tools.
• Do you need technological flexibility (polyglot)?
  • Monolith: Usually one technology stack for the entire application.
  • Microservices: Enable different technologies for different services.
• What are your plans for the long-term maintenance and development of the system?
  • Monolith: Can become difficult to maintain and develop as it grows (technical debt).
  • Microservices: May be easier to maintain and evolve individual components, but require managing the complexity of the whole.
• Are you considering a hybrid approach or a phased transition?

You can start with a well-designed monolith and gradually carve out microservices as needed.

Remember, there is no one right choice. The most important thing is to match the architecture to the specific needs of your project, business and team.