Book Image

Mastering Akka

By : Christian Baxter
Book Image

Mastering Akka

By: Christian Baxter

Overview of this book

For a programmer, writing multi-threaded applications is critical as it is important to break large tasks into smaller ones and run them simultaneously. Akka is a distributed computing toolkit that uses the abstraction of the Actor model, enabling developers to build correct, concurrent, and distributed applications using Java and Scala with ease. The book begins with a quick introduction that simplifies concurrent programming with actors. We then proceed to master all aspects of domain-driven design. We’ll teach you how to scale out with Akka Remoting/Clustering. Finally, we introduce Conductr as a means to deploy to and manage microservices across a cluster.

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Mastering Akka
Christian Baxter
Oct, 2016 | 436 pages
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Table of Contents (17 chapters)
Mastering Akka
Mastering Akka
Credits
Credits
About the Author
About the Author
Acknowledgments
Acknowledgments
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Building a Better Reactive App
Building a Better Reactive App
Understanding the initial example app
Working with the example application
So what's wrong with this application?
Summary
2
Simplifying Concurrent Programming with Actors
Simplifying Concurrent Programming with Actors
Understanding the actor model's origin
Differentiating concurrency and parallelism
Using Akka actors for safe concurrency
A word on dispatchers in Akka
Mailbox types in Akka
Refactoring a bad actor to FSM
Testing your Akka actors
Summary
3
Curing Anemic Models with Domain-Driven Design
Curing Anemic Models with Domain-Driven Design
What is DDD?
Identifying anemic vs rich models
Designing our DDD refactor
Understanding the refactored bookstore code
Fixing the transaction in the order creation process
Improvements needed for the refactor
Refactoring homework
Summary
4
Making History with Event Sourcing
Making History with Event Sourcing
Event sourcing primer
Akka Persistence for event sourcing
Using Cassandra for our persistent store
Refactoring the inventory management module
The refactored sales order processing module
Refactoring homework
Summary
5
Separating Concerns with CQRS
Separating Concerns with CQRS
A brief history of CQRS
CQRS in the event sourced world
Designing our read model implementation
Implementing the Book read model
Refactoring sales order processing
Playing around with the new application
Refactoring homework
Closing comments
Summary
6
Going with the Flow with Akka Streams
Going with the Flow with Akka Streams
Understanding the Reactive Streams API
The Akka Streams API
Refactoring the view building code
Refactoring homework
Summary
7
REST Easy with Akka HTTP
REST Easy with Akka HTTP
Creating RESTful HTTP interfaces
Comparing Akka HTTP to Spray
Creating RESTful interfaces with Akka HTTP
Invoking RESTful APIs with Akka HTTP
Refactoring homework
Summary
8
Scaling Out with Akka Remoting/Clustering
Scaling Out with Akka Remoting/Clustering
Using Akka Remoting
Using Akka Clustering
Using clustering in the bookstore application
Summary
9
Managing Deployments with ConductR
Managing Deployments with ConductR
An overview of ConductR
Installing and setting up ConductR locally
Using the ConductR CLI
Preparing your services for ConductR
Refactoring the bookstore for ConductR
Building and deploying the bookstore bundles
Testing the bookstore modules in ConductR
Summary
10
Troubleshooting and Best Practices
Troubleshooting and Best Practices
Refactoring retrospective
Troubleshooting and best practices for actors
Troubleshooting and best practices for Akka HTTP
Troubleshooting and best practices for Akka Clustering/Akka Remoting
Further reading
Summary

Refactoring homework

The homework for this chapter will be similar in scope to what we did in the Refactoring homework section of Chapter 3, Curing Anemic Models with Domain-Driven Design, where you will finish converting the remaining modules of credit processing and user management over to event sourcing. Make your code changes in the code within the -incomplete bookstore app. When you are done, you can check out my fully converted code in the -complete code-base folder.

I've already added in the data model .proto files for each of these two modules and the generated binding classes. This is so you won't have to go through the trouble of installing the protoc compiler. Also, keep in mind that you won't be able to handle the multiuser lookup functionality in the CustomerRelationsManager yet, so just comment that functionality out for now. You'll get that code working again in the Refactoring homework section, in Chapter 5, Separating Concerns with CQRS,.

With the user-management project,...

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