Microservices architecture – Definition and meaning

What is a microservices architecture?

Microservices architecture describes an approach in which an application is composed of many independent, specialised services. Each of these microservices takes on a clearly defined task, acts independently and exchanges data via standardised interfaces - usually via HTTP APIs or messaging protocols. In contrast to monolithic software systems, in which all components are closely intertwined, a microservices architecture offers significantly more flexibility and scaling options.

Functionality and structure

In applications that are structured according to the microservices principle, the overall system is made up of individual, separately developed and operable services. Typically, each microservice has:

• Its own form of data storage (such as separate databases or its own schemas)
• An independent life cycle in development, deployment and maintenance
• The option to use different technology stacks or programming languages if this meets the requirements

Communication between these services usually takes place via REST APIs, gRPC or messaging systems such as Apache Kafka or RabbitMQ. An API gateway often serves as a central link between clients and backend services in order to control external requests in a targeted manner and distribute them to various microservices.

A striking feature of this architecture is the ability to scale individual microservices independently as required. For example, a compute-intensive service can be operated on additional computer resources without changing the rest of the system landscape.

Areas of application and examples

The use of microservices has become particularly established in dynamic and growth-orientated software projects. Specific use cases show how diverse the benefits can be in practice:

• Cloud-native applications: Companies design modern SaaS solutions with microservices in order to provide new functions in an agile manner and restrict updates specifically to individual system parts.
• E-commerce platforms: In online shops, many providers separate central areas such as the product catalogue, shopping basket, payments or recommendation systems into independent microservices - for example, only the checkout area is scaled up at short notice during promotions without burdening the entire system.
• Financial service providers: Banks or FinTechs encapsulate essential functions - such as account management, transactions or risk analyses - in separate services in accordance with their security and compliance requirements.

For start-ups and young companies in particular, the modular structure offers the opportunity to launch initial versions (minimum viable products) with specific functions and expand them later without major system changes.

Advantages and challenges

The microservices architecture offers many advantages:

• Scalability: Individual microservices can be adapted independently of each other as required so that specific bottlenecks can be addressed efficiently.
• Technological diversity: Teams are free to choose suitable tools, programming languages or databases for each service and can therefore optimally adapt to the respective requirements.
• Easier maintenance: Errors or enhancements generally only affect the affected service; the remaining system parts remain stable.
• Automation: In DevOps environments, the development, testing and delivery of each service can be automated separately - continuous integration and delivery (CI/CD) are a central component here.

However, the advantages are accompanied by increasing demands on planning and operation:

• Complexity of the architecture: a system with many individual services requires well thought-out management, comprehensive monitoring and reliable troubleshooting.
• Distributed data storage: As each service manages its own data, the realisation of cross-transaction consistency becomes a challenge.
• Network dependencies: The intensive communication of distributed components increases traffic and can have an impact on system performance.

For a successful start, it is advisable to keep the number of services manageable at first and to invest in monitoring and automation. Proven concepts such as service discovery, circuit breakers and centralised logging can ensure resilience and transparency during operation.

Tools such as Kubernetes, Docker or service meshes such as Istio support the operation of extensive microservices landscapes and facilitate the orchestration of distributed systems. Nevertheless, the costs and benefits should always be carefully weighed up before existing applications are completely transferred to microservices.