This document provides an introduction to the actor model and Akka.NET framework. It defines key concepts of the actor model such as actors communicating asynchronously via message passing and containing private state. Akka.NET is a toolkit that allows building highly concurrent, distributed, and fault tolerant applications using the actor model. All entities in Akka.NET are actors that process one message at a time in isolation through immutable message passing.

1. Introduction to actor model with examples
on Akka.NET
Arthur Shvetsov 1

2.  Overview and history
 What is an actor model?
 Akka.NET main concepts
 Use-case scenarios
Agenda
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CPU clock speed vs number of cores
CPU clock speed (MHz) # of Cores
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4.  Make classes and functions
 Find areas where you can do multiple things at once
 Queue work onto a new thread or thread pool
 Use synchronization mechanisms to protect shared memory
 Finish work on one thread
 Consume that work on another
How we write multithreaded code?
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6.  Statefulness
 Concurrency
 Recovering from failures
 Bottlenecks
 Availability
Distributed programming pains
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7. Multithreading
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9. - If we don’t want to write multithread code?
- Use concurrency abstractions instead
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10. We won’t talk about TPL today
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11. The Actor Model
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12.  1973 - Concept formulated by Carl Hewitt et al.: “A universal
modular ACTOR formalism for artificial intelligence”
 1986 - Gul Agha, doctoral dissertation "Actors: A Model of
Concurrent Computation in Distributed Systems“
 1986 - Joe Armstrong and others in Ericsson - Erlang programming
language and VM.
 2009 - initial release of Akka framework (JVM, Scala)
 2014.02 - initial release of Akka.NET - Aaron Stannard, Roger
Actor model history
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13.  The Actor Model provides a higher level of abstraction for writing
concurrent and distributed systems.
 Actor Model alleviates the developer from having to deal with explicit
locking and thread management, making it easier to write correct
concurrent and parallel systems.
 Actor Model defines some general rules for how the system’s
components should behave and interact with each other.
What is an actor model?
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14.  No deadlocks
 No shared state
 No global mutable state
 Fault isolation – “let it crash”
 Encapsulation
Actor model benefits
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15.  Akka.NET is a toolkit and runtime for building highly concurrent,
distributed, and fault tolerant event-driven applications on .NET &
Mono.
 Akka.NET is a port of the popular Java/Scala framework Akka to
.NET.
What is Akka.NET?
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16. Everything is an actor!
From OOP to Actor Model paradigm shift
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17. Actor is a code unit organization
What is actor?
OOP Actor
Behavior
State
Synchronous calls
Behavior
State
Asynchronous messages
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18. What is actor?
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19.  All communication is done via message-passing
 All messages are immutable
 Sender and recipient are decoupled, asynchronous
Actors are fundamental units of work & concurrency
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20.  Process messages
 Contain private state, invisible from the outside and changes it upon
reception of a message
 Change behavior between messages (i.e. state machine)
Actors can
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21.  One message processed at a time
 Messages processed in FIFO order
 “At Most Once” delivery guarantied:
 at-most-once delivery
 at-least-once delivery
 exactly-once delivery
Actors promise
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22. Example
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23. Switchable Behaviors
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24. Actor exists as hierarchies
• Parent actors supervise child actors
• Actors are resilient to failures
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25. One-For-One Strategy vs. All-For-One Strategy
Actor supervision
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26.  Communicate with actors through “actor reference”
All actors are identified by a unique address
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27. Actor addresses have location transparency
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29.  Location transparency
 Remote addressing
 Remote messaging
 Remote deployment
Akka.Remote
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30.  Thread
 Instance of an object/component
 Publisher/Subscriber
 Singleton or service (e.g. data access layer)
 State machine
 Load balancer or router
Actor use cases
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31.  http://getakka.net/
 https://github.com/petabridge/akka-bootcamp
References
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32. Thank you!
Arthur Shvetsov
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