Overview of Microservices and Service-Oriented Architecture

What is Service-Oriented Architecture?

Service-Oriented Architecture (SOA) is a software architectural style that structures an application by breaking it down into multiple components called services.
Each service represents a functional business domain.
In SOA applications, each service is independent and provides its own business purposes but can communicate with others across various platforms and languages.
SOA components are loosely coupled and use a central Enterprise Service Bus (ESB) to communicate.

What is a microservice?

On the other hand, a microservice is an architectural style that focuses on maintaining several independent services that work collectively to create an application.
Each individual service within a microservice uses internal APIs to communicate.

Comparison

Although SOA and Microservices seem similar, they are still two different architecture types. Microservices are like a more fine-grained evolution of SOA.
One of their main differences is scope. Microservices are suited to smaller modern web services.
Each service within a microservices generally has one specific purpose, whereas components in SOA have more complex business purposes and functionality and are often implemented as subsystems.
SOA is therefore suited to larger enterprise application environments.
Another significant difference is how both architectures communicate. Every service in SOA communicates through an ESB. If this ESB fails, it compromises functionality across all services.
On the other hand, services within a microservice are entirely independent. If one fails, the rest of the services remain functional. Overall, Microservices are more error tolerant.
Today SOA applications are uncommon as it's an older architecture that may not be suitable for modern cloud-based applications.
However, microservices were developed for the cloud-native movement, and most developers prefer the versatility of service independence they offer.