Book Image

Scala Microservices

By : Selvam Palanimalai, Jatin Puri
Book Image

Scala Microservices

By: Selvam Palanimalai, Jatin Puri

Overview of this book

<p>In this book we will learn what it takes to build great applications using Microservices, the pitfalls associated with such a design and the techniques to avoid them. </p><p>We learn to build highly performant applications using Play Framework. You will understand the importance of writing code that is asynchronous and nonblocking and how Play leverages this paradigm for higher throughput. The book introduces Reactive Manifesto and uses Lagom Framework to implement the suggested paradigms. Lagom teaches us to: build applications that are scalable and resilient to failures, and solves problems faced with microservices like service gateway, service discovery, communication and so on. Message Passing is used as a means to achieve resilience and CQRS with Event Sourcing helps us in modelling data for highly interactive applications. </p><p>The book also shares effective development processes for large teams by using good version control workflow, continuous integration and deployment strategies. We introduce Docker containers and Kubernetes orchestrator. Finally, we look at end to end deployment of a set of scala microservices in kubernetes with load balancing, service discovery and rolling deployments. </p><p></p>

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Table of Contents (12 chapters)
Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
Introduction to Microservices
Introduction to Microservices
Business idea
Implementation
Development issues
Isolation
Microservices
Summary
2
Introduction to Play Framework
Introduction to Play Framework
Quick introduction to Play 2.66
JSON marshalling/Unmarshalling
Play production mode
Summary
3
Asynchronous and Non-Blocking
Asynchronous and Non-Blocking
Being asynchronous
Being asynchronous in Scala
Work Stealing - what makes Play fast!
Summary
4
Dive Deeper
Dive Deeper
Talent search engine
Project structure
Brief overview of the application
Security
Brief introduction to Slick
Pitfalls
Summary
5
Reactive Manifesto
Reactive Manifesto
Reactive hype?
Reactive Manifesto
Manifesto explained
Summary
6
Introduction to Lagom
Introduction to Lagom
Why Lagom?
Brief overview of Lagom
Lagom Service API
Minimized chirper application
Frontend
Multi project builds
Summary
7
CQRS and Event Sourcing
CQRS and Event Sourcing
Data modelling
Event Sourcing
CQRS
Event Sourcing and CQRS
Lagom Persistence API
Summary
8
Effective Communication
Effective Communication
Isolation
Message brokers
Apache Kafka
Lagom Message Broker API
Friend Recommendation
Summary
9
Development Process
Development Process
Getting to know the key ingredients
The feedback loop
Traditional deployments and machine images
Containers
Summary
10
Production Containers
Production Containers
Distributed systems and their essentials
Server automation
An introduction to cluster orchestration
Kubernetes
K8s setup guide
K8s example app
K8s monitoring
K8s security
Caveats
Summary
11
Example Application in K8s
Example Application in K8s
Talent search engine example
Dockerize
Deployment topology
K8s configurations
Installation of K8s
Deploy!
Rolling deployments
Persistent workloads
Summary

Introduction to Play Framework

In the previous chapter, we briefly covered the essence behind microservices. In this chapter, we will introduce Play Framework, and build simple web services using Play Framework.

We will get started with Play Framework, and you will learn the following:

  • How to write web services using Play
  • Play internals such as router and controller
  • REST and stateless
  • Parsing JSON using Play-JSON

You can find the full source of the examples that we try in this chapter at https://github.com/scala-microservices-book/book-examples/tree/master/first-app. However, it is recommended to program the examples mentioned in this chapter by yourself, and use the source only as a reference.

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