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

Creating a microservice for alerts


The Alert service is used to send email alerts and SMS. Alerts can be generated at various levels by other microservices. For example, successful creation of a consumer, provider, service, or an order may require an email to be sent to the relevant stakeholders. Similarly, alerts may be required whenever there is a change in the status of the order or a rating is received. The Alert service does not maintain a local database, it just generates events for each successful alert sent that can be tracked for monitoring purposes. The following table lists the endpoints for the Alert service:

URI

Params

Description

POST /alerts/email

to, cc, subject, body

Sends an alert via email to one or more recipients.

POST /alerts/sms

to, body

Sends an alert via SMS to one or more recipients.

Adding routes

Mostly, the Alert service will listen for events as an Observer and will not receive requests to send alerts via routes. If it is required to send alerts synchronously, the /alerts...