Create Worker Service
Worker Service is a new project template in .net core 3.0, and BackgroundService worker will be created for long running services.
Here is the sample code:
public class Worker : BackgroundService
{
private readonly ILogger<Worker> _logger;
public Worker(ILogger<Worker> logger)
{
_logger = logger;
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
while (!stoppingToken.IsCancellationRequested)
{
_logger.LogInformation("Worker running at: {time}", DateTimeOffset.Now);
await Task.Delay(1000, stoppingToken);
}
}
}
Also in .net core 3.0, Generic Host is recommended for both HTTP and non-HTTP workloads. BackgroundService will be hosted like this:
public static IHostBuilder CreateHostBuilder(string[] args) =>
Host.CreateDefaultBuilder(args)
.ConfigureServices(services =>
{
services.AddHostedService<Worker>();
});
Later, gRPC service will also use Generic Host to host.
Host gRPC service in the worker BackgroundService
In .net core 3.0, there is also a new project template for gRPC service, which will create a new asp.net core project base one the project SDK: Microsoft.NET.Sdk.Web. For Work Service, the project SDK was Microsoft.NET.Sdk.Worker. It seems Microsoft.NET.Sdk.Web contain the Microsoft.NET.Sdk.Worker, and if this is a project that contain gRPC, project SDK need to be changed.
Here is a simple code for csproj file:
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>netcoreapp3.0</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Grpc" Version="1.21.0" />
<PackageReference Include="Grpc.AspNetCore.Server" Version="0.1.20-pre1" />
<PackageReference Include="Google.Protobuf" Version="3.7.0" />
<PackageReference Include="Grpc.Tools" Version="1.21.0" PrivateAssets="All" />
</ItemGroup>
</Project>
gRPC service need to be hosted in the kestrel web host server, which can be created in the BackgroudService.
public class Worker : BackgroundService
{
private readonly ILogger<Worker> _logger;
public Worker(ILogger<Worker> logger)
{
_logger = logger;
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
await Host.CreateDefaultBuilder()
.ConfigureWebHostDefaults(builder =>
{
builder
.ConfigureKestrel(options =>
{
options.ListenAnyIP(0, listenOptions =>
{
listenOptions.Protocols = HttpProtocols.Http2;
});
})
.UseKestrel()
.UseStartup<GrpcServerStartup>();
})
.Build()
.StartAsync(stoppingToken);
}
}
public class GrpcServerStartup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddGrpc();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapGrpcService<GreeterService>();
});
}
}
There are some useful code for special case:
Get the Kestrel server random port
After the Web Host server started, use this code to get the server address:
var address = host.Services.GetService<IServer>()
.Features
.Get<IServerAddressesFeature>()
.Addresses
.FirstOrDefault();
Config the gRPC service as Singleton
services.AddSingleton<GreeterService>();
Code base: https://github.com/celery94/GrpcHostServer
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