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

Introduction to Apache Kafka


Apache Kafka is a distributed streaming platform that allows applications to publish and subscribe to a stream of records. Apache Kafka is not just a message queue, it also allows applications to publish the events that are then stored by Kafka as an immutable log in a fault-tolerant way. It allows the producers and consumers of the events to scale horizontally without affecting each other. Since the events are logged in the same sequence as they are published within Kafka, it allows consumers to replay the log from and up to the desired point to reconstruct views of the application state.

Design principles

Kafka is run as a cluster of one or more servers that act as message brokers (https://en.wikipedia.org/wiki/Message_broker) in the system. Kafka categorizes the stream of records under topics that are used by producers and consumers to produce records and consume them, respectively. Each record consists of a key-value pair and a timestamp.

A typical Kafka cluster...