# PeriodTimer usage


This sample illustrates the use of [`PeriodicTimer`](https://learn.microsoft.com/en-us/dotnet/api/system.threading.periodictimer) to send messages from within an NServiceBus endpoint.

`PeriodicTimer` was introduced in .NET 6 and enables waiting asynchronously for timer ticks.

## Running the project

1.  Start both the Scheduler and Receiver projects.
1.  At startup, Scheduler will schedule a message send to Receiver every 3 seconds.
1.  Receiver will handle the message.

## Code Walk-through

### Define the background service

The [`BackgroundService`](https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.hosting.backgroundservice) defines the job to be run when the host starts. It sets up a `PeriodicTimer` which will tick every 3 seconds. Every time it ticks, a message is sent using NServiceBus.

<!-- snippet: SendMessageJob -->

```cs
class SendMessageJob(IMessageSession messageSession) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using var timer = new PeriodicTimer(TimeSpan.FromSeconds(3));

        while (await timer.WaitForNextTickAsync(stoppingToken))
        {
            await messageSession.Send("Receiver", new MyMessage(), stoppingToken);
        }
    }
}
```

<!-- endsnippet -->

### Configure host

The host is configured with NServiceBus and the background service created above. When the host starts, the background service is run and messages will be sent periodically.

<!-- snippet: ConfigureHost -->

```cs
var builder = Host.CreateApplicationBuilder();

var endpointConfig = new EndpointConfiguration("Scheduler");
endpointConfig.UseTransport(new LearningTransport());
endpointConfig.UseSerialization<SystemJsonSerializer>();

builder.Services.AddNServiceBusEndpoint(endpointConfig);

builder.Services.AddHostedService<SendMessageJob>();
```

<!-- endsnippet -->