NCronJob

Scheduling made easy

NCronJob

A Job Scheduler sitting on top of IHostedService in dotnet.

Often times one finds themself between the simplicity of the BackgroundService/IHostedService and the complexity of a full-blown Hangfire or Quartz scheduler. This library aims to fill that gap by providing a simple and easy to use job scheduler that can be used in any dotnet application and feels "native".

So no need for setting up a database, just schedule your stuff right away! The library gives you two ways of scheduling jobs:

1. Instant jobs - just run a job right away (or with a small delay; or with a given date and time)
2. Cron jobs - schedule a job using a cron expression

The whole documentation can be found here: NCronJob Documentation

• NCronJob
  • Features
  • Not features
  • Short example
  • Triggering an instant job
  • Support & Contributing

Features

• The ability to schedule jobs using a cron expression
• The ability to instantly run a job
• Parameterized jobs - instant as well as cron jobs!
• Integrated in ASP.NET - Access your DI container like you would in any other service
• Get notified when a job is done (either successfully or with an error).
• Retries - If a job fails, it will be retried.
• The job scheduler supports TimeZones. Defaults to UTC time.
• Minimal API for Jobs - implement jobs in an oneliner

Not features

As this is a simple scheduler, some features are not included by design. If you need these features, you might want to look into a more advanced scheduler like Hangfire or Quartz.

• Job persistence - Jobs are not persisted between restarts of the application.
• Job history - There is no history of jobs that have been run.
• Progress state - There is no way to track the progress of a job. The library will support notifying when a job is done, but not the progress of the job itself.

Short example

There are two ways of defining a job.

Minimal Job API

You can use this library in a simple one-liner:

builder.Services.AddNCronJob((ILoggerFactory factory, TimeProvider timeProvider) =>
{
    var logger = factory.CreateLogger("My Anonymous Job");
    logger.LogInformation("Hello World - The current date and time is {Time}", timeProvider.GetLocalNow());
}, "*/5 * * * * *");

With this simple lambda, you can define a job that runs every 5 seconds. Pass in all dependencies, just like you would with a Minimal API.

Via the IJob interface

1. Import the namespace (or let your IDE do the dirty work)

using LinkDotNet.NCronJob;

2. Create a job

public class PrintHelloWorld : IJob
{
    private readonly ILogger<PrintHelloWorld> logger;

    public PrintHelloWorld(ILogger<PrintHelloWorld> logger)
    {
        this.logger = logger;
    }

    public Task RunAsync(JobExecutionContext context, CancellationToken token)
    {
        logger.LogInformation("Hello World");
        logger.LogInformation("Parameter: {Parameter}", context.Parameter);

        return Task.CompletedTask;
    }
}

3. Register the NCronJob and the job in your Program.cs

builder.Services.AddNCronJob(options =>
    options.AddJob<PrintHelloWorld>(j => 
    {
        // Every minute and optional parameter
        j.WithCronExpression("* * * * *")
         .WithParameter("Hello World");
    }));

4. Run your application and see the magic happen

Triggering an instant job

If the need arises and you want to trigger a job instantly, you can do so:

public class MyService
{
  private readonly IInstantJobRegistry jobRegistry;
  
  public MyService(IInstantJobRegistry jobRegistry) => this.jobRegistry = jobRegistry;

  public void MyMethod() => jobRegistry.RunInstantJob<MyJob>("I am an optional parameter");
}

Support & Contributing

Thanks to all contributors and people that are creating bug-reports and valuable input: