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The Principles of Microservices
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by sam newman
notes by benjamin santana


What are Microservices
======================

Small autonomous services that work well together.

Emphasis on the autonomous. We are talking about independent
processes, they communicate via APIs. You know you are making a good
system when you can take a microservices, change it and redeploy it
without having to touch anything else.

Each microservice only focus on doing one thing right.


Service Oriented Architecture? SOA?
-----------------------------------
Microservices are just an opinionated way of doing SOA. Microservice
would be a very good implementation of SOA.

Size?
-----
My microservice should only be focus on doing one thing, and one thing well.


Summary
-------

Independent processes communicating over APIs focusing on doing one thing, and
one thing well, that allow for independent change.


Benefits of Microservices
=========================

Team organization
-----------------

Allow you to align your organization to your architecture. Usually when you
have a big code base you are usually fighting for the code base, who can check
in now, and it is common to step into each other toes.

You can align ownership of different services to independent teams. The
communication between teams matches the communication with the API's of the
different microservices.

Conway:
> Any organization that designs a system will produce a design whose structure
> is a copy of the organization's communication structure.


Ship Faster and Safer
---------------------

Say we have a one line change in a monolith. You want to deploy it, first you
have to run a full set of tests, since you are not sure if this affects
something you did not touch you have to run the whole suite, that takes time.

Now you want to deploy it, but deploying it is a big task, you have to deploy
the whole thing. This makes teams less prone to deploy so they deploy less with
more changes, making stuff more prone to fail changes, making stuff more prone
to fail.


Security Concerns
-----------------

In a monolith you have one big wall that protects the whole application. In
microservices you can focus on more sensitive services scrutinize and
secure them the most.

Maybe we want to secure the whole app the same, but with microservices you have
that flexibility.


Adopt Technologies More Easily
------------------------------

Each microservice is independent, so as long as we expose the same API we have
the freedom of using different/multiple technologies.

Embrace Uncertainty on a Digital Age
------------------------------------

With finer grain APIs we have more opportunity to adapt.