On Stateless Microservices

This post discusses the stateless microservice design pattern; it is meant as support material for other posts of mine that discuss microservices, mainly michael.gr - The Stateful Microservice.

Is statelessness a requirement for a microservice?

In another post (see michael.gr - So, what is a Microservice, anyway?) I discuss what a microservice really is, and I come to the conclusion that despite various attempts out there to define microservices using twenty-item-long lists of characteristics, a good working definition could be as simple as this:

A microservice is a scalable and resilient module.

Even if you disagree with the terseness of this definition, and you regard microservices as necessarily more than that, I hope you will at least agree that it is precisely scalability and resilience that statelessness in microservices aims to address, so my definition serves its purpose at least in the context of this series of posts.

There are many who will try to convince you that in order to build a scalable and resilient system, you need statelessness; so much so, that microservices have almost come to be regarded as synonymous with statelessness. This post examines whether this is that in fact so, and what is the cost of doing things this way.

So, what is a Microservice, anyway?

This article attempts to shed some light on what a microservice really is; it is meant as support material for other posts of mine that discuss microservices, mainly michael.gr - The Stateful Microservice.

What is a microservice?

If you go looking for information out there, you will find many different descriptions of what a microservice is; these descriptions exhibit considerable difference of opinion, and to the extent that they agree, it is largely the result of copy-paste. One common theme in these descriptions is that in trying to define this elusive concept, they tend to assign fictitious properties to it. Often, the claims have nothing to do with what a microservice technically is, but rather with impertinent concepts such as the allegedly "independent" software development style around microservices, or some alleged organization of microservices "around business capabilities". Even when the claims do manage to stick within the technical realm, they range from the unwarranted to the preposterous. I have seen statements to the effect that a microservice is supposed to live in its very own source code repository, that a microservice must be independently deployable, that microservices must communicate with each other via REST, etc. (My favorite one is that they must necessarily be stateless; more on that in another post of mine; see  michael.gr - On Stateless Microservices.)

What is wrong with Scala

This is part of a series of posts in which I am documenting what is wrong with certain popular programming languages that I am (more or less) familiar with.  The aim of these posts is to support a future post in which I will be describing what the ideal programming language would look like for me.  

I will be amending and revising these texts over time.

What is wrong with C#

This is part of a series of posts in which I am documenting what is wrong with certain popular programming languages that I am (more or less) familiar with.  The aim of these posts is to support a future post in which I will be describing what the ideal programming language would look like for me.  

I will be amending and revising these texts over time.