Microservices – especially what it is NOT !!

Microservice is another term in the industry, which was picked up in last few years, and everyone using it in one context or another. Some are using it in right context, and some are using to look cool, without properly understanding the concept.

Microservice in itself doesn’t have a standard, it’s an architectural style, and there are many flavors of interpretations and implementations of microservice.

According to Martin Fowler: “Microservice architectural style is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms, often an HTTP resource API. These services are built around business capabilities and independently deployable by fully automated deployment machinery. There is a bare minimum of centralized management of these services, which may be written in different programming languages and use different data storage technologies.

To put it in simple statement – breakdown application into small services that each perform one business function and can be developed, deployed, and scaled independently.

Microservice properties

There is already lot of literature, books and articles available to understand Microservices. One of the book I will personally recommend will be Microservices with Azure, authored by Namit TS and Rahul Rai, and I personally got a chance to tech review it.

But rather than going into Microservices details, let me list down few things which doesn’t qualify as microservices, and technologist should understand that and stop creating confusion.

What is NOT a Microservice

  • A published API is not a microservice. Microservice could be an architectural implementation behind API, but that detail is independent of API specification. You don’t say “here is Microservice ready to be consumed by other applications”, you only say “here is API specifications ready to be consumed by other applications”
  • A functionality exposed as an API by another system is not a microservice, it’s just an API. It doesn’t matter how it is implemented in the backend, for consumer application it’s just an API.
  • A simple API implemented as part of a monolithic application is not a microservice, again it’s just an API.
  • If a service is dependent on another service, it’s not a microservice
  • If a service is not independently deployable, it’s not a microservice.
  • If a service can’t be updated independently, it’s not a microservice.
  • A monolithic set of services grouped together and deployed in a Docker container is not a microservice.

and in the end,

  • Stop putting terms like microservices within Conceptual Architecture diagrams. Conceptual architecture is all about appropriate decomposition of the system without going into specifics of interface specification or implementation details.

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