Touch and Touched Messages

This guide demonstrates how to use the Touch and Touched messages in Proto.Actor. The Touch message is an auto-respond message used to check actors’ liveness. When an actor receives a Touch message, it automatically responds with a Touched message without processing the Touch message.

Setting Up Auto-Respond for Touch Message

Example: Using Touch and Touched Messages

using System;
using Proto;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        var props = Props.FromProducer(() => new MyActor());

        var actorSystem = new ActorSystem();
        var rootContext = actorSystem.Root;

        var pid = rootContext.Spawn(props);

        // Send a Touch message to check liveness
        var response = await rootContext.RequestAsync<Touched>(pid, new Touch());

        // Check the response
        if (response != null)
        {
            Console.WriteLine("Actor is alive");
        }
        else
        {
            Console.WriteLine("Actor did not respond");
        }

        // Keep the application running to observe the output
        Console.ReadLine();
    }
}

class MyActor : IActor
{
    public Task ReceiveAsync(IContext context)
    {
        if (context.Message is string message)
        {
            Console.WriteLine(message);
        }

        return Task.CompletedTask;
    }
}

Explanation

1. Initialize Actor System:

   • An ActorSystem instance is created, and the root context is obtained.

2. Send Touch Message:

   • The Touch message is sent to the actor to check its liveness.
   • The actor system automatically responds with a Touched message without the actor processing the Touch message.

3. Verify Response:

   • The response is checked to determine if the actor is alive.
   • A message is printed to the console based on whether the actor responded.

Running the Example

To run this example:

• Copy the code into a .cs file.
• Ensure you have the Proto.Actor library installed.
• Compile and run the program.
• Observe the console output to see the auto-respond functionality in action.

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By following this guide, you can implement liveness checks for actors using the Touch and Touched messages in Proto.Actor.