Key Points
- A microservices architecture breaks an application into separate, independent services that each own a specific business function.
- Unlike monolithic systems, microservices allow independent deployment, targeted scaling, and isolated fault tolerance across components.
- The main benefits of leveraging microservices include help with scalability, parallel workflows across teams, technology flexibility, and app resilience.
- Defining clear service boundaries is crucial, as poorly scoped services can create distributed monoliths that carry microservices overhead with reduced benefits.
- Microservices are most suitable for large, complex systems with varying scalability and uptime requirements, while simpler systems can make do with a monolithic architecture.
Modern workloads require applications that can handle unpredictable traffic, frequent updates, and growing feature sets. Microservices architecture addresses this by breaking each microservice into independent codebases, each deployable and scalable on its own.
This guide will walk you through what microservices are, how they differ from monolithic systems, and how to decide whether adopting this specific architecture is the right move for your environment.
Understanding the microservices architecture
A microservices architecture is a software building approach that breaks down applications into smaller services that operate independently. Rather than packaging every function into a single unit, each application capability is maintained as its own service.
Each microservice typically:
- Owns a single, well-defined service and is scoped only within that function.
- Manages its own database rather than sharing one central database with the rest of the system.
- Interacts using APIs to allow each independent application to function coherently.
- Functions independently, allowing teams to update, restart, or scale one service without redeploying the whole application.
This application architecture allows IT teams to create a distributed application environment where components can evolve separately. This allows different teams to work in parallel and scale services to match demand while preventing failures from cascading from one codebase to another.
What is a microservice, and how does it differ from monolithic systems
To get a better picture, let’s compare them side-by-side:
| Comparison areas | Monolithic systems | Microservices |
| Structure | All functionality lives within a single codebase and runs as one unit. | Functionality is split across independent services that run separately. |
| Deployment strategy | Easy initial deployment, but the entire application requires redeployment to accommodate changes. | Each service can be independently targeted to receive updates without affecting the entire system. |
| Component coupling | Components share code, memory, and database. | Services interact only through well-defined APIs. |
| Scaling | Scaling requires the whole application to change. | Individual services can be scaled independently to meet demand. |
| Fault tolerance | A single failure can bring down the entire application. | Failures are isolated per service, retaining functionality to the rest of the system. |
| Technology stack | Locked to a single language and framework across the whole codebase. | Each service can use the language, framework, or database best suited to its function. |
| Team workflow | Multiple teams must work within the same codebase, requiring cross-team collaboration during releases. | Teams own individual services and can develop, test, and release in parallel. |
Microservices are typically adopted to support scalability and the specific demands of evolving systems. This architecture also helps teams work in parallel, using different languages or frameworks, speeding up development cycles. The improved fault tolerance of microservices also prevents issues from cascading across components.
However, the benefits that make microservices powerful can also introduce unwanted overhead complexity. For instance, microservices don’t operate on shared databases, making data alignment a challenge alongside potential component failures that can stem across multiple points in the environment.
Defining service boundaries within microservices architecture
Boundaries set the scope of a microservice, including the service it’s responsible for, data ownership, and where that ownership ends. For example, a payment service is limited to handling transactions and payment records; its scope shouldn’t intrude on logistics-related workflows.
Well-defined boundaries should align microservices with the capabilities they actually perform, minimize dependencies between services, and support independent scaling.
On the other hand, poorly-defined boundaries can deliver noise as services constantly call each other, multiplying network traffic and latency. Additionally, this can cause performance bottlenecks and increase system complexity.
To maximize the benefits of microservices architecture, teams must set business-aligned boundaries up front, refining them as systems evolve. Without properly defined boundaries, organizations can end up with a distributed monolith that carries microservices overhead minus the flexibility.
Evaluating whether a microservices architecture is for you
Before committing to microservices, you must first weigh where they fit in your environment, where they don’t, and what alternatives exist besides utilizing microservices architecture.
When microservices are the right choice
Microservices deliver the most value in environments where demands exceed what monolithic systems can offer. They tend to be the right choice when your organization falls under the following criteria:
- Large and complex systems: Consider microservices if your application has grown to a point where a unified codebase is difficult to safely maintain or release.
- Teams need to work in parallel: Multiple teams are contributing to the same system, and a shared codebase has become a coordination bottleneck.
- Varying scalability requirements: Some functions handle far heavier loads than others and need to scale on their own.
- Continuous delivery is a priority: Pick microservices if your organization releases frequently and can’t afford downtime during new releases.
When microservices are not the right choice
In some cases, a simpler architecture can deliver better results without the operational overhead that comes with a microservices architecture. Avoid microservices if your environment meets the following:
- Operating simple applications: A monolith can deliver simple functionality with far less infrastructure and complexity.
- Teams lack experience: Without skills in service orchestration, monitoring, and failure handling, the architecture can cause more problems than it solves.
- Infrastructure resources are limited: Microservices require tooling and capacity that smaller environments may not have.
- Independent scaling isn’t necessary: If an app’s components scale together at manageable rates, splitting them apart can add unnecessary costs.
Some alternatives to microservices architecture
The choice of IT teams isn’t constrained between microservices and monolith applications. There are several architectural models that sit between them, and could be a better fit depending on your environment’s requirements and capabilities.
Modular monolith architecture
A modular monolith architecture is a single deployable unit organized into separated internal modules. This helps IT teams to combine the clear internal separation of microservices with the operational simplicity of a monolith. However, this architecture scales as a single unit, which can limit the flexibility of each module.
Service-oriented architecture
A service-oriented architecture (SOA) organizes different functionalities into shared services, often coordinated through an enterprise service bus (ESB). This promotes the reuse of services and can support enterprise-wide integrations. While it offers interoperability of different services, ESB slowdowns, changes, or outages can cascade across every connected service.
Understand microservices architecture first before adoption
Microservices support scalability and offer management flexibility, but they come with significant overhead. Understanding your environment’s requirements against those trade-offs is what determines whether a simpler system will serve you better, or whether the move to microservices is worth taking.
