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

Using Kafka for Helping Hands


The Helping Hands application uses Apache Kafka to implement the observer model and send asynchronous events among microservices. It is also used as an event store to capture all the state change events generated from microservices that are consumed by the Lookup service to build a consolidated view to server lookup requests. The Alert microservice of the Helping Hands application also receives the alert events via the Kafka topic and sends an email asynchronously.

Apache Kafka includes five core APIs:

  • The Producer API allows applications to publish streams of events to one or more topics
  • The Consumer API allows applications to consume published events from one or more topics
  • The Streams API allows transforming streams from input topics and publish the results to output topics
  • The Connect API allows support for various input and output sources to capture and dump stream of events
  • The AdminClient API allows topics and server management along with other Kafka management...