Triggering instant jobs¶

NCronJob allows you to trigger jobs instantly. This is useful when you want to run a job immediately without waiting for the next scheduled time. For example you get a API request and want to offload the work to a background job immediately.

Instant jobs are like “regular” CRON jobs and inherit from IJob. The only difference is that they are triggered manually. So also CRON jobs can be triggered instantly.

public class MyJob : IJob
{
    public Task RunAsync(IJobExecutionContext context, CancellationToken token)
    {
        ParameterDto dto = (ParameterDto)context.Parameter;
        // Do something
        return Task.CompletedTask;
    }
}

As CRON jobs, they have to be registered in the AddNCronJob method.

Services.AddNCronJob(options => 
{
    options.AddJob<MyJob>(); // No need to specify a CRON expression
});

There is no need of a CRON expression for instant jobs. Also passing in parameters doesn’t do anything, they will be passed in differently. Let’s have a look at how to trigger an instant job. Imagine we have a Minimal API where we want to send an E-Mail:

app.MapPost("/send-email", (RequestDto dto, IInstantJobRegistry jobRegistry) => 
{
    var parameterDto = new ParameterDto
    {
        Email = dto.Email,
        Subject = dto.Subject,
        Body = dto.Body
    };

    jobRegistry.RunInstantJob<MyJob>(parameterDto);
    return Results.Ok();
});

The RunInstantJob method takes the job type and the parameters as arguments. Optionally you can pass in a CancellationToken as well. The job will be executed immediately.

Starting a job with a delay¶

If you find the need of delaying the execution of an instant job, you can use the RunScheduledJob method with a TimeSpan as a delay. The same as RunInstantJob applies here, the job has to be registered in the AddNCronJob method.

app.MapPost("/send-email", (RequestDto dto, IInstantJobRegistry jobRegistry) => 
{
    var parameterDto = new ParameterDto
    {
        Email = dto.Email,
        Subject = dto.Subject,
        Body = dto.Body
    };

    jobRegistry.RunScheduledJob<MyJob>(TimeSpan.FromMinutes(5), parameterDto);
    return Results.Ok();
});

Starting a job at a specific date and time¶

If you want to start a job at a specific date and time, you can use the RunScheduledJob method with a DateTimeOffset as a parameter. The same as before: The job has to be registered.

app.MapPost("/send-email", (RequestDto dto, IInstantJobRegistry jobRegistry) => 
{
    var parameterDto = new ParameterDto
    {
        Email = dto.Email,
        Subject = dto.Subject,
        Body = dto.Body
    };

    jobRegistry.RunScheduledJob<MyJob>(new DateTimeOffset(2024, 1, 1, 0, 0, 0, TimeSpan.FromHours(2)), parameterDto);
    return Results.Ok();
});

Priority¶

Instant jobs are executed with a higher priority than CRON jobs. This means that if you have a CRON job that is scheduled to run at the same time as an instant job, the instant job will be executed first (and if both of them are competing for the same resources, the instant job will be executed).

Minimal API¶

Running instant jobs can also be done with the minimal API (Minimal API), which allows to create an anonymous lambda, that can also contain dependencies.

app.MapPost("/send-email", (RequestDto dto, IInstantJobRegistry jobRegistry) => 
{
    var parameterDto = new ParameterDto
    {
        Email = dto.Email,
        Subject = dto.Subject,
        Body = dto.Body
    };

    jobRegistry.RunInstantJob(async (HttpClient httpClient) => 
    {
        await httpClient.PostAsync("https://api.example.com/send-email", new StringContent(JsonSerializer.Serialize(parameterDto)));
    });
    return TypedResults.Ok();
});