Book Image

Microservices with Clojure

By : Anuj Kumar
Book Image

Microservices with Clojure

By: Anuj Kumar

Overview of this book

The microservice architecture is sweeping the world as the de facto pattern with which to design and build scalable, easy-tomaintain web applications. This book will teach you common patterns and practices, and will show you how to apply these using the Clojure programming language. This book will teach you the fundamental concepts of architectural design and RESTful communication, and show you patterns that provide manageable code that is supportable in development and at scale in production. We will provide you with examples of how to put these concepts and patterns into practice with Clojure. This book will explain and illustrate, with practical examples, how teams of all sizes can start solving problems with microservices. You will learn the importance of writing code that is asynchronous and non-blocking and how Pedestal helps us do this. Later, the book explains how to build Reactive microservices in Clojure that adhere to the principles underlying the Reactive Manifesto. We finish off by showing you various ways to monitor, test, and secure your microservices. By the end, you will be fully capable of setting up, modifying, and deploying a microservice with Clojure and Pedestal.
Table of Contents (18 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
Index

Chapter 7. Achieving Immutability with Datomic

"Most of the biggest problems in software are problems of misconception."

- Rich Hickey

Microservices depend on the underlying database to reliably store and retrieve data. Often applications like Helping Hands need to store user transactions consistently along with user locations that may change over time. Instead of updating the user location permanently and losing the history of the changes, a good application must maintain the change in data so that it can be queried over time. Such requirements expect the data stored in the database to be immutable. Datomic (http://www.datomic.com/) is one such database that not only provides durable transactions but also has the concept of immutability built into its core so that users can query the state of the database over a period of time. Datomic is also written in Clojure, which is the technology stack of choice for the Helping Hands application. In this chapter, you will learn about the following...