Microsoft Orleans

Distributed systems, without distributed complexity

Virtual actors

Model your application as grains with stable identities, behavior, and state. Orleans activates and locates them on demand.

Automatic lifecycle

Let the runtime place, activate, deactivate, and recover grains while your code focuses on business behavior.

Elastic by design

Scale from one process to a resilient cluster without changing the programming model or managing actor placement.

Built for .NET

Use interfaces, dependency injection, async/await, generic hosting, and the libraries your team already knows.

Familiar code. Distributed by default.

Define a grain contract, implement it as an ordinary .NET class, and call it from anywhere in the cluster.

Define a grain

Counter.cs

public interface ICounter : IGrainWithStringKey
{
  Task<int> Add(int value);
}

public sealed class Counter : Grain, ICounter
{
  private int _value;

  public Task<int> Add(int value) =>
      Task.FromResult(_value += value);
}

Call it from a client or another grain

Program.cs

var counter = client.GetGrain<ICounter>("orders");
var total = await counter.Add(1);

Production capabilities included

PersistenceKeep grain state in Azure Storage, Cosmos DB, relational databases, Redis, DynamoDB, or custom stores.

StreamingBuild reliable producers and consumers over managed, persistent, or in-memory stream providers.

Timers and remindersSchedule transient work or durable callbacks which survive activations and failures.

Distributed transactionsCoordinate state changes across grains with decentralized ACID transactions.

Start building

Build your first appCreate a silo, define a grain, and make your first distributed call.

Read the docsExplore grains, hosting, deployment, streaming, persistence, and runtime concepts.

Browse samplesLearn from complete applications and focused examples maintained in this repository.

Join the projectRead the source, open an issue, or contribute to Orleans on GitHub.