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Applied Akka Patterns
A Hands-On Guide to Designing Distributed Applications
Michael Nash and Wade Waldron
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Applied Akka Patterns
by Michael Nash and Wade Waldron
Copyright © 2017 Michael Nash, Wade Waldron. All rights reserved.
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December 2016: First Edition
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Revision History for the First Edition
2016-12-09: First Release
See http://oreilly.com/catalog/errata.csp?isbn=9781491934883 for release details.
The O’Reilly logo is a registered trademark of O’Reilly Media, Inc. Applied Akka Patterns,
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978-1-491-93488-3
[LSI]
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Preface
Reactive Application Development is the new frontier of software development. As the
prevalence of connected devices has increased, so has the amount of data available. Older
techniques for processing that data in a single-threaded batch simply can’t hold up under the
demands presented by this new world. Big data is on the rise and we need new tools and new
techniques to deal with it.
Often, the solution to modern problems doesn’t come from the present, but rather from the
past. Many of today’s new tools for processing big data are in fact based on the older concept
of actors. Actors are the key concept from which Akka was built, but it has its roots in the past.
It isn’t a new concept; rather, it’s an old one brought to light in the modern world.
As we set forth to explore Akka, actors, streams, and all the other things associated with them,
we will be approaching them from the perspective of a real-world concern: the problem of
how to schedule a group of people across a variety of projects while optimizing both for the
time they have available, as well as their skill sets. This is a complex problem, not one easily
solved in an afternoon. But it is an interesting issue that provides a lot of room for depth. It is
also a problem that most software developers will be involved with at some point during their
career. We will refer back to this problem throughout our exploration of Akka.
But before we get to solving the problems of our domain, we have to first understand the
tools that we have available. We also need to understand why those tools exist, and what kinds
of problems they were intended to solve. We need to know the origin of Akka, with its roots
in the Actor Model. We need a guiding set of principles to help us stitch together our
application, found in our exploration of domain-driven design (DDD). From there, we can
begin to build out our domain, using all of the tools Akka provides. We can explore the use of
simple actors and how they relate to streams. We can take our system and distribute across
multiple nodes, providing better fault tolerance, availability, and of course, scalability.
But first, we need to know where it all came from.
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Acknowledgments
We would like to thank the many people who helped make this book possible, including the
Akka team, both within Lightbend and in the greater community, as well as our editor, Nan
Barber, and our reviewers, Konrad Malawski, Sean Glover, and Petro Verkhogliad. We
especially want to thank our families for their patience and support.
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