In a previous version of a Professional C# book I’ve written a complete chapter on how to create Windows Services with the .NET Framework. Using .NET Core 3.0, it’s a lot easier to create Windows Services: just a single line of code is needed to convert a background worker to a Windows Service.
Create a Worker
With .NET Core 3.0, a background worker can be created using Visual Studio or the dotnet CLI command dotnet new worker.
With this template, a Program class is created that uses the Host class. The method CreateDefaultBuilder is used to setup the dependency injection container, configuration, and logging. The dependency injection container managed by the Host class is configured by invoking the method ConfigureServices. In the generated code, the extension method AddHostedService is used to register a background class that implements the interface IHostedService. This interface is indirectly implemented by the Worker class by deriving from the base class BackgroundService. The interface IHostedService defines the methods StartAsync and StopAsync. Adding a hosted service, invoking the Run method of the host starts the host and in turn invokes the startup of the IHostedService.
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**public** **class** Program
{
**public** **static** **void** Main(``**string**``[] args)
{
CreateHostBuilder(args).Build().Run();
}
**public** **static** IHostBuilder CreateHostBuilder(``**string**``[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureServices((hostContext, services) =>
{
services.AddHostedService<Worker>()
.Configure<EventLogSettings>(config =>
{
config.LogName = "Sample Service"``;
config.SourceName = "Sample Service Source"``;
});
});
}
The
_Host_class is also used by ASP.NET Core 3.0 Web projects. The_WebHost_class from .NET Core 2.0 is replaced by the more generic_Host_class.
The Worker class derives from the class BackgroundService. BackgroundService implements the interface IHostedService and defines the abstract method ExecuteAsync. This abstract method is called by the StartAsync method in the BackgroundService. StartAsync is defined by the IHostedService interface. With the implementation of the Worker class, ExecuteAsync uses an endless loop (until cancellation is requested) and writes a log message once a second.
#.net core #asp.net core #aspnetcore #dotnetcore #windows service
