A short and sweet introduction to Microsoft Orleans - https://dotnet.github.io/orleans/ - OSS actor programming framework from Microsoft Research. As presented in Alt.Net Israel (http://altnet.azurewebsites.net/) meeting group, Dec 2016.

1. A BRIEF INTRO TO
MICROSOFT
ORLEANS
URI GOLDSTEIN / @URIG / HTTP://URIG.IO/
Alt.Net Israel

2. MICROSOFT ORLEANS
A framework for building distributed
applications
• Made by Microsoft Research
• Free and Open Source (MIT License)
• Production Ready (Halo 4, Azure Service Fabric)

3. TWO GOALS
• Simple Distributed
Programming
• Scalable by Default
• The Actor Model of
Programming

4. ACTOR PROGRAMMING MODEL
• An Actor is “Unit of Computation” that upon receiving a
Message:
• Can send Messages to other Actors.
• Can Create new Actors.
• Designates the behavior to be used
for the next Message it receives.
State +
Logic

5. ACTORS
• Encapsulate State and Logic
• Run Concurrently
• Communicate Asynchronously
Via Message Passing
• Addressable
(Addresses can go in Messages)

6. SOMEWHAT CONTRIVED EXAMPLE
Uri
WhatsApp
Group
Shay
Boris“Wanna hear a secret?”

7. ORLEANS: GRAIN = VIRTUAL ACTOR
• Grains are C# Classes
• Derived from GrainBase
• Implement an Interface (ex: IUser or IConversation)
• Messages Passing = Calling Interface Methods
• Ex: SendMessageToMembers(string text)
• Can be Stateless or Stateful

8. GRAIN EXAMPLE
public class ConversationGrain : Grain, IConversation
{
// State
private string AdminId;
private IEnumberable<IUserGrain> Members;
// Receive messages
public async Task SendMessageToAdmin(string message)
{
// Send a message
var admin = GrainFactory.GetGrain<IUserGrain>(AdminId);
await admin.GetMessage(message);
}
//...
}

9. GRAIN LIFECYCLE
• Managed by Silos and Clusters
• Grains always exist
• Can be Active / Inactive
• Garbage Collected
• Single instance if Statefull
• Many instances if Stateless Orleans Cluster
Silo Silo Silo

10. GRAIN COMMUNICATION
• Messages = Method Calls
• Method Calls are Queued
• Grains are Single Threaded
• Addresses are C# References
• Location is Transparent
var grain = GrainFactory
.GetGrain<IUserGrain>("Uri");
await grain.SayHello("World");

11. GRAIN PERSISTENCE
Choose:
• No State (Think functional!)
• Transient State: In Memory
• Persistent State:
• Azure Table Storage
• Shared ATS
• Roll your own
• Configurable per Grain
• Implicitly Read upon Activation
• Explicitly Written by Grain
Logic
• Storage Provider in charge of
Serialization

12. DEPLOYMENT
• Silos are self hosting
• So Clusters run anywhere Windows can
Ex: Azure Cloud Services (Worker Roles)
• Server to Server over TCP
• Entry point is GrainClient
• Message Passing (Method Call), or
• Observer Pattren (Pub/Sub)
Orleans
Client
Orleans
Cluster
Interface
s

13. SAMPLE ARCHITECTURE
Orleans Cluster
(Azure Cloud Service)
Silo Silo Silo
Azure Table
Storage
Shard
asp.net
Web API
Shard
Shard
Request
Request

14. SAMPLE ARCHITECTURE
Orleans Cluster
(Azure Cloud Service)
Silo Silo Silo
Azure Table
Storage
Shard
asp.net
Web API
Shard
Shard
Request
Request

15. THANK YOU
• Orleans website
http://dotnet.github.io/orleans
• Orleans on GitHub
https://github.com/dotnet/orle
ans
• 30 min intro from Carl Hewitt
who invented the Actor Model
http://tinyurl.com/CarlHewitt
•Ask me anything:
Uri Goldstein
twitter.com/urig
http://urig.io/