namespace Microsoft.Extensions.Hosting
{
    public interface IHostedService
    {
        Task StartAsync(CancellationToken cancellationToken);
        Task StopAsync(CancellationToken cancellationToken);
    }
}

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace MvcTest
{
    public class SampleHostedService : IHostedService
    {
        private readonly ILogger<SampleHostedService> _logger;

        public SampleHostedService(ILogger<SampleHostedService> logger)
        {
            _logger = logger;
        }

        public async Task StartAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("Starting Hosted service");

            while (!cancellationToken.IsCancellationRequested)
            {
                _logger.LogInformation("Hosted service executing - {0}", DateTime.Now);
                await Task.Delay(TimeSpan.FromSeconds(2), cancellationToken);
            }
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            _logger.LogInformation("Stopping Hosted service");
            return Task.CompletedTask;
        }
    }
}

namespace MvcTest
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton<IHostedService, SampleHostedService>();

services.AddHostedService<SampleHostedService>();

 public void Configure(IApplicationBuilder app, IHostingEnvironment env)

Startup.cs(82,56): error CS0104: 'IHostingEnvironment' is an ambiguous reference between
'Microsoft.AspNetCore.Hosting.IHostingEnvironment' and 'Microsoft.Extensions.Hosting.IHostingEnvironment'

D:\MvcTest>dotnet run
info: MvcTest.SampleHostedService[0]
      Starting Hosted service
info: MvcTest.SampleHostedService[0]
      Hosted service executing - 02/19/2019 14:45:10
info: MvcTest.SampleHostedService[0]
      Hosted service executing - 02/19/2019 14:45:12
info: MvcTest.SampleHostedService[0]
      Hosted service executing - 02/19/2019 14:45:14
Ctrl+C
Application is shutting down...
Hosting environment: Development
Content root path: D:\MvcTest
Now listening on: https://localhost:5001
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.

namespace Microsoft.Extensions.Hosting
{
    public abstract class BackgroundService : IHostedService, IDisposable
    {
        protected BackgroundService();
        public virtual void Dispose();
        public virtual Task StartAsync(CancellationToken cancellationToken);
        public virtual Task StopAsync(CancellationToken cancellationToken);
        protected abstract Task ExecuteAsync(CancellationToken stoppingToken);
    }
}

namespace MvcTest
{
    public class PrinterHostedService : BackgroundService
    {
        private readonly ILogger<SampleHostedService> _logger;

        public PrinterHostedService(ILogger<SampleHostedService> logger)
        {
            _logger = logger;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            _logger.LogInformation("Starting Hosted service");

            while (!stoppingToken.IsCancellationRequested)
            {
                _logger.LogInformation("Hosted service executing - {0}", DateTime.Now);
                await Task.Delay(TimeSpan.FromSeconds(2), stoppingToken);
            }
        }
    }
}

namespace MvcTest
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddHostedService<PrinterHostedService>();

D:\MvcTest>dotnet run
Hosting environment: Development
infoContent root path: D:\MvcTest
Now listening on: https://localhost:5001
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.
: MvcTest.SampleHostedService[0]
      Starting Hosted service
info: MvcTest.SampleHostedService[0]
      Hosted service executing - 02/19/2019 15:00:23
info: MvcTest.SampleHostedService[0]
      Hosted service executing - 02/19/2019 15:00:25
info: MvcTest.SampleHostedService[0]
      Hosted service executing - 02/19/2019 15:00:27
Application is shutting down...
^C

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

public abstract class ScopedBackgroundService : BackgroundService
{
    private readonly IServiceScopeFactory _serviceScopeFactory;

    public ScopedBackgroundService(IServiceScopeFactory serviceScopeFactory)
    {
        _serviceScopeFactory = serviceScopeFactory;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using (var scope = _serviceScopeFactory.CreateScope())
        {
            await ExecuteInScope(scope.ServiceProvider, stoppingToken);
        }
    }

    public abstract Task ExecuteInScope(IServiceProvider serviceProvider, CancellationToken stoppingToken);
}

 dotnet add package ncrontab

┌───────────── minute (0 - 59) 
│ ┌───────────── hour (0 - 23) 
│ │ ┌───────────── day of month (1 - 31) 
│ │ │ ┌───────────── month (1 - 12) 
│ │ │ │ ┌───────────── day of week (0 - 6) (Sunday to Saturday; 
│ │ │ │ │                                       7 is also Sunday on some systems) 
│ │ │ │ │ 
│ │ │ │ │ 
* * * * *

* * * * * *
- - - - - -
| | | | | |
| | | | | +--- day of week (0 - 6) (Sunday=0)
| | | | +----- month (1 - 12)
| | | +------- day of month (1 - 31)
| | +--------- hour (0 - 23)
| +----------- min (0 - 59)
+------------- sec (0 - 59)

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using NCrontab;
using static NCrontab.CrontabSchedule;

public abstract class ScheduledScopedBackgroundService : ScopedBackgroundService
{
    private CrontabSchedule _schedule;
    private DateTime _nextRun;

    protected abstract string Schedule { get; }

    public ScheduledScopedBackgroundService(IServiceScopeFactory serviceScopeFactory)
     : base(serviceScopeFactory)
    {
        _schedule = CrontabSchedule.Parse(Schedule, new ParseOptions { IncludingSeconds = true });
        _nextRun = _schedule.GetNextOccurrence(DateTime.Now);
    }

    public override async Task ExecuteInScope(IServiceProvider serviceProvider, CancellationToken stoppingToken)
    {
        do
        {
            var now = DateTime.Now;
            if (now > _nextRun)
            {
                await ScheduledExecuteInScope(serviceProvider, stoppingToken);
                _nextRun = _schedule.GetNextOccurrence(DateTime.Now);
            }
            await Task.Delay(1000, stoppingToken); //1 second delay
        }
        while (!stoppingToken.IsCancellationRequested);
    }

    public abstract Task ScheduledExecuteInScope(IServiceProvider serviceProvider, CancellationToken stoppingToken);
}

using System;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

public class MyScheduledTask : ScheduledScopedBackgroundService
{
    private readonly ILogger<MyScheduledTask> _logger;

    public MyScheduledTask(
        IServiceScopeFactory serviceScopeFactory,
        ILogger<MyScheduledTask> logger) : base(serviceScopeFactory)
    {
        _logger = logger;
    }

    protected override string Schedule => "*/10 * * * * *"; //Runs every 10 seconds

    public override Task ScheduledExecuteInScope(IServiceProvider serviceProvider, CancellationToken stoppingToken)
    {
        _logger.LogInformation("MyScheduledTask executing - {0}", DateTime.Now);
        return Task.CompletedTask;
    }
}

namespace MvcTest
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddHostedService<MyScheduledTask>();

D:\MvcTest>dotnet run
Hosting environment: Development
Content root path: D:\MvcTest
Now listening on: https://localhost:5001
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.
info: MyScheduledTask[0]
      MyScheduledTask executing - 02/19/2019 19:18:50
info: MyScheduledTask[0]
      MyScheduledTask executing - 02/19/2019 19:19:00
info: MyScheduledTask[0]
      MyScheduledTask executing - 02/19/2019 19:19:10
Application is shutting down...
^C

%USERPROFILE%/.omnisharp

{
  "RoslynExtensionsOptions": {
    "LocationPaths": [
      "C:\\lib\\roslynator"
    ]
  }
}

Write-Host "Download, unzip and enable Roslynator for Visual Studio Code"

$name = "josefpihrt.Roslynator2017"
$url = "https://marketplace.visualstudio.com/items?itemName=$name"
$currentDir = $PSScriptRoot
$file = "$currentDir\Roslynator.zip"

$pattern = "<script class=`"vss-extension`" defer=`"defer`" type=`"application\/json`">(.*?)<\/script>"
$regex = [regex]"(?m)$pattern"
Write-Host "Grab the home page of the $name."
$dom = (New-Object Net.WebClient).DownloadString($url); 
if($dom -and $dom -match $pattern) 
{
    $matches = $regex.Match($dom)
    $jsonText = $matches[0].Groups[1]

    $json = ConvertFrom-Json $jsonText

    $version = $Json.versions[0].version # Parse the json in the page for the latest version number
    $parts = $name.Split(".")
    $publisher = $parts[0]
    $package = $parts[1]

    # Assemble the url for the vsix package
    $packageUrl = "https://marketplace.visualstudio.com/_apis/public/gallery/publishers/$publisher/vsextensions/$package/$version/vspackage"
    Write-Host "Download the vsix package: $packageUrl"
    (New-Object Net.WebClient).DownloadFile($packageUrl, $file)

    Write-Host "Using $currentDir as the current dir."
    Write-Host "Unzip $file."
    $shellApp = new-object -com shell.application 
    $zipFile = $shellApp.namespace($file) 
    $destination = $shellApp.namespace($currentDir) 
    $destination.Copyhere($zipFile.items(), 0x14)# overwrite and be silent

    Write-Host "Delete VS specific files. Otherwise they will interfere with the MEF services inside OmniSharp."
    Remove-Item "$currentDir\Roslynator.VisualStudio.Core.dll","$currentDir\Roslynator.VisualStudio.dll", "$currentDir\Roslynator.VisualStudio.pkgdef"

    $omnisharpJsonFilePath = "$env:USERPROFILE\.omnisharp\omnisharp.json";
    Write-Host "Create $omnisharpJsonFilePath file."
    $omnisharpJson = @" 
{{
  "RoslynExtensionsOptions": {{
    "LocationPaths": [
      "{0}"
    ]
  }}
}}
"@ -f $currentDir -Replace "\\","\\"
    $omnisharpJson | Out-File "$omnisharpJsonFilePath" -Confirm

    Write-Host "Done!"
}
else
{
    Write-Host "Failed to find the packageUrl!"
}

PS D:\Prog\1396\RoslynatorVSCode> .\update.ps1
Download, unzip and enable Roslynator for Visual Studio Code
Grab the home page of the josefpihrt.Roslynator2017.
Download the vsix package: https://marketplace.visualstudio.com/_apis/public/gallery/publishers/josefpihrt/vsextensions/Roslynator2017/1.7.0/vspackage
Using D:\Prog\1396\RoslynatorVSCode as the current dir.
Unzip D:\Prog\1396\RoslynatorVSCode\Roslynator.zip.
Delete VS specific files. Otherwise they will interfere with the MEF services inside OmniSharp.
Create C:\Users\Vahid\.omnisharp\omnisharp.json file.

Confirm
Are you sure you want to perform this action?
Performing the operation "Output to File" on target "C:\Users\Vahid\.omnisharp\omnisharp.json".
[Y] Yes  [A] Yes to All  [N] No  [L] No to All  [S] Suspend  [?] Help (default is "Y"):
Done!

Today, the Entity Framework Core team announces the first release candidate (RC1) of EF Core 5.0. This is a feature complete release candidate of EF Core 5.0 and ships with a "go live" license. You are supported using it in production.  

For many years now I’ve advocated not using the repository pattern on top of an ORM such as Entity Framework. There are many reasons why that I’ll try and cover throughout this post based on ways that I’ve seen it implemented. Meaning, this post is talking about poorly implemented approaches or pitfalls that I’ve seen. 

We're going to use Dapper.NET on our project; that much is not in doubt. However, we're not going to start development with it, and it will not be the only ORM in use. The plan is to develop this project using Entity Framework, and later optimize to use Dapper.NET in certain scenarios where the system needs a performance boost.