How do I send a signal to ELSA workflow using C#, SendSignal and SignalReceived activities?

Question

I'd like to send a signal from my C# API code, probably using the SendSignal activity to a workflow that will receive that signal using the SignalReceived activity.

Answer 1

To send a signal to a workflow from your own code, such as a controller or any other class, you can use the ISignaler service.

Here's an example:

[ApiController]
[Route("myapi")]
public class MyApi: Controller
{
    private readonly ISignaler _signaler;

    public MyApiController(ISignaler signaler)
    {
        _signaler = signaler;
    }
    
    [HttpPost("send-signal")]
    public async Task<IActionResult> SendSignal(CancellationToken cancellationToken)
    {
        var startedWorkflows = await _signaler.TriggerSignalAsync("MySignal", cancellationToken: cancellationToken);
        return Ok(startedWorkflows);
    }
}

A complete sample project can be found here.