1. Modern Backends
Service Fabric & Actor Model
Damir Dobric, daenet

2. Agenda Backends Today “Right” Scaling Approach
Multitier Architecture
Scaling fiction
Backend Limits
“Right” Scaling Approach
Loadbalancing
Partitioning
Microservices
Azure Service Fabric Actor Model
Mathematical Model
Activation, States,..

3. “The Backend”

4. Caching helps, but.. Service Service Service Service Service Service
Client
Service
Client DB
CACHE
Service
Client
Service
Service
To scale up DB, we will need multiple nodes.
But how about data consistency? Same instance of entity can be instantiated on multiple nodes. Frameworks like WCF & Co. do not solve this serious issue.
Sync/Transactions?

5. Nonlinear Speed-up can even fail What is the problem?
Build 2014
5/26/2018
What is the problem?
Nonlinear
Additional power does not scale well
Speed-up can even fail
Number of nodes
Speed up 5 10
Traditional models/runtime are not suitable
© 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

6. Scale Cube X Horizontal scale More nodes NLB Y Functional Scale
Microservices Z
Data Partitioning
Separate Tenants
Separate by regions …

7. Service Fabric Supports scale in all 3 dimensions
Client
Service
DATA
Client
Service
Client
Service
Service
DATA
To scale up DB, we will need multiple nodes.
But how about data consistency? Same instance of entity can be instantiated on multiple nodes. Frameworks like WCF & Co. do not solve this serious issue.
Sync/Transactions?

8. Service Types Stateless State full Actor Stateless Actor State full
Anything Else
Console App
JAVA
ASP.NET …

9. Service Fabric Demo

10. Partitions and Replicas
Secondary of P1
Node
Primary of P1
P61 P3 P7 P2 P5
P42 P1 P6 P3 P7 P2 P5 P4 P1
Secondary of P1
State full services are replicated P6 P3 P7 P2 P5
P42 P1 A1
Services are deployed in partitions. A1
Multiple services can be deployed in a single partition

11. Partitions and Replicas
This is a new primary n P1
Old Primary of P1 fails P6 P3 P7 P2 P5 P4 P1 P6 P3 P7 P2 P5 P4 P1
Secondary of P1 P6 P3 P7 P2 P5 P4 P1
If the node fails a new replica is automatically created.
New secondary of P1

12. Actor Model

13. The Actor Model Mathematical theory of computation
Build 2014
5/26/2018
The Actor Model
Mathematical theory of computation
Introduced 1973 by Hewitt, Bishop, and Steiger
A framework and basis for reasoning about concurrency
Actors as primitives of concurrent computation
© 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

14. The actor model is a mathematical model of concurrent computation.
Definition
The actor model is a mathematical model of concurrent computation.

15. The “Actor” Actor STATE PERSISTENCE ASYNC ONLY SINGLE THREAD EXECUTION
All methods and property getters must return a promise. Property setters are not allowed as .NET does not allow them to return a completion promise. Similarly, .NET events are not allowed. Method arguments
Orleans does not eliminate execution non-determinism. Promises are resolved asynchronously and the order in which continuation delegates execute is unpredictable

16. Actor is defined by interface
Build 2014
5/26/2018
Actor is defined by interface
Marker interface to indicate actor interfaces
public interface IHelloActor : IActor { Task<string> SayHello(string greeting); }
All actor interface operations must be asynchronous
© 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

17. Implementing the actor type
Build 2014
5/26/2018
Implementing the actor type
public class HelloActor : Actor, IHelloActor {
Task<string> SayHello(string greeting)
var resp = "You said: '" + greeting + "', I say: Hello!";
return Task.SayHello(resp); }
© 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

18. Activation and deactivation
IHelloActor helloActor =
ActorProxy.Create<IHelloActor>(actorId, appName);
CLIENT
public override Task OnActivateAsync() {
return base.OnActivateAsync(); }
public override Task OnDeactivateAsync()
return base.OnDeactivateAsync();
ACTOR

19. Identifier can be of types:
Build 2014
5/26/2018
Example
Identifier can be of types:
{long , GUID, String}
ActorId actorId = ActorId.NewId();
string applicationName = "fabric:/CalculatorActorApp";
IHelloActor helloActor =
ActorProxy.Create<IHelloActor>(actorId, applicationName);
double result = helloActor .AddAsync(2, 3).Result;
© 2014 Microsoft Corporation. All rights reserved. Microsoft, Windows, and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

20. Single Activation Principle
Actor
Actor
Actor X

21. New Instance on other Node
Actor
Actor X
Actor
Actor X

22. State vs. Stateless Stateless: State full:
public class HelloActor : Actor, IHelloActor
State full:
public class HelloActor : StatefullActor<MyState>, IHello [DataContract] public class State { [DataMember] public string WhateverSerializable; }

23. State persistence State Actor Persistence Provider
SQL ?

24. State replica + persistence1
State
Actor
Actor
Call SaveAsync() to explicitly enforce saving of the state 2
But State is also saved implicitly, after method comlettion.
Persistence Provider ?
await this.SaveStateAsync();

25. References
Hewitt about actor model:
Actor Model popular videos
State Persistence
Service Fabric

26. Recap Backends Today Scaling Cube Service Fabric
Multitier Architecture can lead to bottleneck
Backend Limits (More nodes can mean less perf.)
Scaling Cube
Loadbalancing (As we know it)
Partitioning (SF provides it out of the box.)
Microservices (SF containers PaaS ready)
Service Fabric
Reliable Cluster. Can host “anything”
Actor Model is cool for specific problem domains
It behaves as OO, but is NOT!

27. with Service Fabric and Actor Model
Q & A
Modern Backends
with Service Fabric and Actor Model
Damir Dobric
Microsoft PTSP (Partner Technical Solution Specialist) Microsoft Most Valuable Professional
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