What is Microservice Architecture

An architecture of the present day? How and why has it emerged and what are the values it brings to businesses?

Microservice architecture is a method of developing applications by breaking them down into smaller, loosely coupled, fine-grained units (services). This approach has become increasingly popular in recent years for various reasons. We'll look at the nature of microservice architecture, weigh its benefits and drawbacks, and try to provide some insight into when it might be a good choice.

From the early days of enterprise application development, engineering and management suffered from the same problem: the "cost" of adding new features grows in proportion to the application size and complexity. It is still a problem, but the industry has invented ways to reduce this effect.

Monolithic architecture

Let's step back and look more closely at how engineers approached architecture some time ago.

The entire application source code was built into a single deployment unit (a "monolith"). It wasn't a big deal for smaller apps, but problems occur when it comes to mid-sized and large systems.

Even minor changes to the code base resulted in spinning up an entirely new release cycle: rolling out to testing/pre-release environments, regression testing, and finally deploying to production. At the same time, issues discovered in production initiated an expensive and challenging rollback process—you had to roll back the entire app. That's why huge QA and system administration departments were an inherent part of enterprise giants a decade ago.

The fragility and significant maintenance overhead of a monolithic approach for rapidly growing technology enterprises put their businesses at risk that they couldn't tolerate.

Service-oriented architecture

In response to the shortcomings of monolithic design, a new method has emerged: service-oriented architecture (SOA). Roughly, the idea behind SOA is to divide the software into smaller, purpose-driven components and connect them via an enterprise service bus (ESB). For its customers, each service is a black box (they don't need to know about the service's implementation details), but they all adhere to a common communication protocol (SOAP, WCF, etc.). Some of the limitations of monolithic architecture were overcome as a result of this: services can be developed, tested, and deployed independently by different engineering teams, shortening the development cycle. However, XML-based protocols were heavy, and a single service bus created a single point of failure, posing new issues for performance and stability.

Finally, microservices

The expansion of web technologies and cloud platforms has influenced the development of a new method for tackling the issue: microservice architecture. By taking the most beneficial aspects of SOA (like isolated services) and replacing the service bus with lightweight, technology-agnostic APIs, it was possible to build an architecture that appeared to be relatively similar at first glance but was distinct in practice.

Instead of relying on a centralized messaging system, microservices communicate with one another through specialized APIs. By eliminating a single point of failure, the system's stability and reliability were dramatically improved, and the likelihood of complete collapse was significantly reduced. It also made it possible to have different APIs for each context. Because services are no longer bound by a particular protocol, it is considerably easier to integrate third-party services. This enables tighter integration with the global services market and more effective use of the API economy, improving customer value and reducing development costs.

Microservice architecture key principles

The concept that is referred to as "microservice architecture" does not have a single formal definition. But most of the implementations have the following characteristics:

Microservices are often the processes that communicate over a network via technology-agnostic protocols such as HTTP. Because such APIs lack the complicated logic of ESBs, they are more lightweight and performant.
Microservices are typically focused on business capabilities and priorities. This reflects the nature of the organization, where multiple teams with different areas of expertise can give the most significant outcomes in engineering certain services.
Depending on the circumstances, services can be implemented using a variety of programming languages, databases, hardware, and software environments. It enables the achievement of a balance between efficiency and fragmentation of the technology stack. Because there are no one-size-fits-all tools or technology.
Microservices are lightweight, messaging-enabled, context-bound, autonomous, independently deployable, decentralized, and built and deployed automatically. A well-architected app with microservice architecture, backed by DevOps best practices, will provide a short time to market cycle, good product quality, and predictable reaction to engineering team scaling.

The advantages and disadvantages of microservices

Every programming paradigm has advantages and disadvantages. Despite appearing promising, microservice architecture has drawbacks that bring its use into question in some cases. Let's look at the pros and cons of microservices.

Pros:

Tech agnostic. Each microservice is a mini-application and can utilize a unique set of technologies. This tech-agnostic strategy lets business and technical teams choose the right stack. It eliminates the need for compromises due to incompatibility or an ageing stack.
Optimized development time and cost. This strategy saves money over time, despite the upfront costs of setting up an agile team and developing a microservices architecture. Faster time to market, lower system upgrade and scaling costs, etc., impact the bottom line. The flexibility of microservices impacts team organization. It enables building in-house and remote agile teams accountable for certain modules or business activities. This boosts productivity and delivery speed.
Painless upgrade and migration. Microservices help fast-evolving systems swiftly adapt to newer technologies. Individual components help companies move to new frameworks or tools. Instead of changing a huge system's code, engineers develop and enhance individual components. Microservices reduce costs for modernization and for fighting tech debt in large-scale projects.
Better maintainability. Increased component autonomy makes microservices easier to support and maintain. Each service can be updated and deployed separately. Modern DevOps technologies and CI/CD processes for automated deployment adapt to each team's needs. This improves application development and deployment.
Better scalability. Modular systems are less expensive and easier to scale than monoliths. Because services are containerized and loosely coupled, system integrity threats are low. Autonomous services can be scaled based on load and processing power without disrupting other services or inflating infrastructure costs.
Evolution. Many products started as monoliths and migrated to microservices as needed. It's easier to segregate functions via an API. When microservice complexity grows, you can do the same. Separate services, on the other hand, can be upgraded unevenly. This enables businesses to be more agile by better allocating time and resources to developing functionality that meets current business goals and changing market demands. Instead of investing in full-scale system development, businesses can precisely prioritize critical functions and processes.

Cons:

Complexity. When considering service size as a primary organizing criterion, the alternative of internal modularization within a monolith may result in a more straightforward design. This increases the importance of understanding the overall app architecture and the interdependencies between components.
Security. For an app to be genuinely secure, you must secure each microservice since each individual service represents a potential point of risk.
Maintenance. The code base of microservices is easier to maintain because they are considered discrete small apps. At the same time, it multiplies the effort for monitoring to detect anomalies and quickly respond to incidents.
Fragmentation. The other side of being technologically agnostic is the need to have diverse engineering teams capable of supporting and improving a broad and fragmented tech stack.
Performance. Network communication between microservices imposes extra latency compared to in-process calls within a monolith. Although this latency rarely matters, some applications that require a near-realtime reaction cannot tolerate it.

Conclusion

At this point, we have a general understanding of microservices. This approach to architecture has certain advantages over monolithic systems. However, there are some disadvantages to them as well. The primary source of the drawbacks is when and how they are utilized. Microservices are ideal for large applications that rely heavily on other services. Monolithic systems remain the best option for simple or time-critical applications. As a result, microservices are quickly becoming the dominant software development paradigm (especially in the enterprise area). Engineers should consider it when designing the architecture of the application with a reasonable degree of criticism.