Actors and microservices - Can Two Walk Together?

The Actor Model is an alternative approach to writing concurrent software without the problems introduced by multithreaded concurrency.
“Virtual Actors” are a new development of the actor model, aimed for solving distributed concurrency issues, providing better productivity, and building cloud native scalable architecture.

With the recent trend of moving into microservices based architecture, there is some confusion about Actors, microservices, and how they fit together.

This session will introduce Actors, Virtual Actors, and how they make distributed application programming a lot simpler. We will then explore the idea of building a microservices architecture on top of Actors, how they combine, and some of the lessons learnt at Gigya doing that.

Presented at DevconTLV, March 2016

Transcript

1. Actors, Microservices…
   Rotem Hermon
   @margolis20
   Can two walk
   together?
   

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2. Actors?
   

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3. Concurrency
   

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4. Multithreading
   

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5. The problem with multi-threaded concurrency
   • Shared memory and state
   • Race conditions
   • Locks and deadlocks
   • Blocking calls
   • Hard to understand and maintain
   • Not easily distributed
   

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7. The Actor Model
   • Formalized in 1973 (Carl Hewitt)
   • Concurrency by Message Passing
   • Avoids problems of threading and locking
   

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8. An Actor
   • Lightweight
   • Never shares state
   • Communicates through asynchronous messages
   • Mailbox buffers incoming messages
   • Processes one message at a time
   

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9. An Actor
   • Lightweight
   • Never shares state
   • Communicates through asynchronous messages
   • Mailbox buffers incoming messages
   • Processes one message at a time
   • Single threaded
   

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10. The Actor Model
    • Higher abstraction level
    • Simpler concurrent programming model
    • Write single-threaded code (easier to understand)
    • Concurrency and scale via actor instances
    • Maximizes CPU utilization
    • Easy to distribute
    

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12. Distributed
    Concurrency
    

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13. Distributed
    Concurrency
    

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14. Virtual Actors
    • A simplified Actors implementation with a higher abstraction
    level
    • Introduced by Microsoft Research – Project Orleans
    • A port to Java – Orbit (by EA)
    

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15. Virtual Actors
    • Goals:
    • Make distributed application programming easier
    • Prefer developer productivity and transparent scalability
    • “A programming model and runtime for building cloud
    native services”
    

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16. Virtual Actors
    • A Virtual Actor:
    always exists
    and
    never fails
    

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17. Virtual Actors
    Actor types:
    • Worker
    • An auto-scaling processing unit – multiple instances created by
    framework as needed
    

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18. Virtual Actors
    Actor types:
    • Single Activation
    • Guaranteed to have a single active instance in the cluster
    

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19. Virtual Actors
    Actor types:
    • Single Activation
    • Guaranteed to have a single active instance in the cluster
    • A Stateful application middle-tier!
    

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20. Virtual Actor Framework
    • A runtime providing virtual “actor space”, analogues to
    virtual memory
    • Handles Actor placement, activation and GC when needed
    • Balances resources across the cluster, provides elastic
    scalability
    

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21. Simplified Programming Model
    • An Actor is a class, implementing an interface with
    asynchronous methods
    • The caller of an Actor uses the actor interface via a proxy
    • Messaging is transparent and handled by the runtime.
    Programmers deal with interfaces and methods
    

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22. (Actors are actually
    Nanoservices)
    

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23. A single Actors universe?
    

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24. Back to microservices
    

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25. Actor based microservices
    Service A
    Service B
    ServiceB
    Interface
    Actor
    IMyServiceB
    

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26. Actor based microservices
    Service A
    Service B
    ServiceB
    Interface
    Actor
    IMyServiceB
    ServiceB
    HTTP
    Listener
    

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27. Actor based microservices
    Service A
    Service B
    ServiceB
    Interface
    Actor
    IMyServiceB
    ServiceB
    Client
    ServiceB
    HTTP
    Listener
    JSON over HTTP
    

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29. Thank You!
    Rotem Hermon
    @margolis20
    VP Architecture @ Gigya
    

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