Microservice architecture for scalable web projects: when and why implement it?

When Netflix rewrote its monolithic video service into microservices, the company was able to serve more than 200 million users worldwide. When Uber split its platform into hundreds of independent services, the time to develop new features was reduced many times over. These success stories have created a wave of enthusiasm around microservice architecture, but behind every such story are years of complex engineering work and millions of dollars of infrastructure investment. Microservices are not just a fashion trend, but an architectural solution with its own clear indications for use.

What is a microservice architecture?

Microservice architecture is an architectural style of developing a website or application as a set of loosely coupled services. Each microservice is responsible for a specific business function, can be developed independently, and uses its own technology platform.

Unlike a monolithic architecture, where all components are tightly coupled and deployed as a single entity, microservices operate autonomously and interact through well-defined APIs. This fundamental difference determines all the advantages and disadvantages of this approach.

Advantages of microservice architecture

Independent scaling

One of the key benefits of microservices is the ability to scale only those components of the system that experience the most load. If a payment processing service receives more requests than a user management service, you can add additional instances of only the former, saving resources.

Technological diversity

Each microservice can use the optimal technology for its tasks. A machine learning service can be written in Python, a highly loaded API in Go, and a user interface in Node.js. This allows you to choose the best tool for each task.

Fault tolerance

When implemented correctly, the failure of a single microservice should not cause a complete system failure. The other services continue to function, and the problematic component can be quickly repaired or replaced.

Flexibility of development

Different teams can work on different microservices in parallel without interfering with each other. This speeds up development and allows teams to specialise in specific domains.

Challenges of microservice architecture

Infrastructure complexity

Managing dozens or hundreds of microservices requires a complex infrastructure. Container orchestration, monitoring, logging, and request tracing systems are required. This greatly complicates DevOps processes.

Network interactions

Every call between microservices is a network request, which adds latency and points of failure. You need to carefully design interactions, implement retry logic, circuit breakers and other fault tolerance patterns.

Data consistency

Maintaining data consistency between microservices becomes a challenge. Traditional ACID transactions don't work in a distributed environment, a move to eventual consistency and saga patterns is required.

Testing

Testing a distributed system is much more complicated than a monolithic application. Integration tests require raising multiple services, which slows down and complicates the development process.

When should you choose microservices?

Critical availability requirements

Microservices become a necessity when a system must provide high availability (99.9% or higher) with minimal downtime. Failure isolation allows problems to be localised: a failure in the recommendation service will not affect the ability to make purchases, and problems with the payment system will not stop catalogue browsing. This is especially critical for systems where every minute of unavailability means the loss of thousands of dollars.

Different scaling requirements

If different parts of the system have different load patterns, microservices allow for optimal resource allocation. For example, in an e-commerce system, a product catalogue may be read more often than it is updated, while a payment system requires high reliability.

Need for technological diversity

When different parts of the system are better implemented on different technologies, microservices provide such an opportunity. This is especially true for systems with machine learning, image processing, and high-performance computing components.

DevOps process maturity

Microservices require a mature infrastructure: automated deployment, monitoring, and logging. Without this, managing multiple services will be a nightmare.

Implementation strategies

Strangler Figure Pattern

Gradual migration from monolith to microservices by taking functionality piecemeal. New functionality is created as a microservice, old functionality is gradually migrated.

Database-per-Service

Each microservice must have its own database. This provides weak coupling, but makes it more difficult to ensure data consistency.

API Gateway

A single entry point for all external requests that routes them to the appropriate microservices. Solves the problems of authentication, rate limiting, and API versioning.

Technical considerations

Containerisation and orchestration

Docker and Kubernetes have become the de facto standards for deploying microservices. They provide isolation, scaling, and service lifecycle management.

Monitoring and observability

Distributed tracing, centralised logging and metrics are critical to understanding system behaviour. Tools like Jaeger, Prometheus, ELK stack become an integral part of the architecture.

Security

Every microservice represents a potential point of attack. It is necessary to implement security-by-design: traffic encryption, authentication between services, least privilege principle.

Conclusion

Microservice architecture is a powerful tool for building scalable, fault-tolerant systems. The decision to implement microservices should be based on specific project requirements, system complexity and infrastructure maturity.

For start-up projects, it is better to start with a well-structured monolith and move to microservices as the complexity and team grows. This will avoid premature optimisation and allow you to focus on creating business value.

Remember: architecture should serve the business, not the other way round. Choose the approach that best fits your goals, resources, and constraints.

Need help selecting an architecture for your project? Our team of experts can help you analyse requirements, assess infrastructure readiness and choose the best architectural approach. We specialise in designing scalable systems - from migrating monoliths to microservices to building highly loaded platforms from scratch. Contact us for a consultation on architecting your next project.