In my actual society we have several jobs on VM handle by windows task scheduler. I wanted to find a solution to handle these jobs in a more efficient way with a better monitoring system. In our previous article, we explored Quartz.NET. I will try to talk about an alternative to Quartz.NET.

Hangfire is an open-source framework designed to simplify the process of creating, processing, and managing background jobs. It offers a range of features that make it a robust and versatile tool for handling various types of tasks. In this article will delve into the key components of Hangfire, discuss its benefits, and provide a practical example of how to use it in a .NET Core application.

Hangfire

• Hangfire is an open-source framework that helps you create, process, and manage your background jobs.
• There are 4 main parts to Hangfire:
  • Dashboard
  • Server
  • Storage
  • Jobs

Dashboard - Client

• The Hangfire Dashboard is a web application that allows you to monitor and manage background jobs.
• You can use the dashboard to:
  • View the status of background jobs.
  • View the history of jobs.
  • Retry failed jobs.
  • Delete jobs.

Database - Storage

• Each piece of information about the jobs is stored in a database. Hangfire supports multiple storage options, including:
  • SQL Server
  • SQL Azure
  • MSMQ
  • Redis

Server

• The Hangfire Server is a .NET Core application that processes background jobs.
• Each Server is responsible for processing jobs from a queue.

Jobs

In Hangfire, a "job" refers to a task or unit of work that needs to be executed. There are many types of jobs:

• Fire-and-forget jobs
• Delayed jobs
• Recurring jobs
• Continuations
• Batch jobs (Pro version)
• Batch Continuations (Pro version)

In this article, we will focus on Fire-and-forget and Recurring jobs.

Diagram

flowchart LR
DatabaseHangfire[(Database)] <--> Dashboard{Dashboard}
InternalServer[InternalServer] --> DatabaseHangfire
OtherServer[OtherServer] <--> DatabaseHangfire
InternalJob[InternalJob] <--> InternalServer
InternalJob2[InternalJob2] <--> InternalServer
ExternalJob[ExternalJob] <--> OtherServer

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Practical Example

You can find the source code in the repo.

Prerequisite

• Docker

Run the project

• You can run the project directly with docker-compose or DotNet Aspire. I will try to make a future article about DotNet Aspire.

You need a database to store the jobs. You can use SQL Server or SQL Azure. In this example, we will use SQL Server.

Create a Solution Core application that uses Hangfire to perform background processing. The project will be divided into 3 parts:

• GoatHangfire.Dashboard (ASP.NET Core Web Application)
• GoatHangfire.InternalJob (Library)
• GoatHangfire.ExternalJob (Worker Application)

GoatHangfire.ExternalJob

For some reason, you may want to separate the Hangfire Dashboard from the Hangfire Server. In this case, you can create a new project for the Hangfire Server. That's why I use the terms External Jobs.

Cons:

• You will not be able to schedule jobs from the dashboard. Only see the status of the jobs.

Pros:

• You can deploy the Hangfire Server on a different server.

Create the project in solution folder

dotnet new worker -o GoatHangfire.ExternalJob
dotnet add package Hangfire.Core
dotnet add package Hangfire.NetCore
dotnet add package Hangfire.SqlServer
dotnet add package Microsoft.Data.SqlClient

In program.cs

HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
builder.Services.AddHostedService<ExternalGoatJob>();

// AddHangfire: This method adds Hangfire services to the services container. It takes a configuration action where you can configure various aspects of Hangfire.
builder.Services.AddHangfire(configuration => configuration
    // SetDataCompatibilityLevel(CompatibilityLevel.Version_180): This sets the compatibility level for serialized data.
    // Version 180 is the latest and it's recommended to use the latest version unless you need to support older Hangfire servers.
    .SetDataCompatibilityLevel(CompatibilityLevel.Version_180)
    // This adds a filter that automatically retries failed jobs.
    // The Attempts property is set to 0, which means jobs won't be retried if they fail.
    .UseFilter(new AutomaticRetryAttribute { Attempts = 0, })
    // This changes the type serializer to use simple assembly names.
    // This can help avoid issues when moving jobs between different environments.
    .UseSimpleAssemblyNameTypeSerializer()
    // This applies recommended JSON serializer settings.
    // It's generally a good idea to use this unless you have specific serialization needs that it doesn't meet.
    .UseRecommendedSerializerSettings()
    // This adds a log provider that outputs colored logs to the console.
    .UseColouredConsoleLogProvider() 
    // This configures Hangfire to use SQL Server for storage.
    // The connection string is retrieved from the application's configuration with the key "HangfireDb
    .UseSqlServerStorage(builder.Configuration.GetConnectionString("HangfireDbConnection")));

BackgroundService

We create a new class called ExternalGoatJob that inherits from BackgroundService. This class will be responsible for adding a recurring job to the Hangfire server every minute.

public class ExternalGoatJob : BackgroundService
{
private readonly IRecurringJobManager _recurringJobs;
private readonly IGoatExternalService _goatService;

public ExternalGoatJob(IRecurringJobManager recurringJobs,IGoatExternalService goatService)
  {
    _recurringJobs = recurringJobs;
    _goatService = goatService;
  }
  protected override Task ExecuteAsync(CancellationToken stoppingToken)
  {
    _recurringJobs.AddOrUpdate("ExternalGoatJob",() => _goatService.ExecuteAsync(), Cron.Minutely);
    return Task.CompletedTask;

  }
}

We just created a new recurring job called "ExternalGoatJob" that will execute the ExecuteAsync method of the IGoatExternalService every minute. The external job can be run directly on your server, you just need to publish the project then run the executable or you can create a service.

sc create GoatHangfire.ExternalJob binPath= "C:\path\to\GoatHangfire.ExternalJob.exe"
sc start GoatHangfire.ExternalJob

GoatHangfire.InternalJob

The project will be directly referenced by HangfireDashboard.

Cons:

• You can't deploy the Hangfire Server on a different server.

Pros:

• You can directly schedule jobs from the dashboard.

dotnet new classlib -o GoatHangfire.InternalJob
dotnet add package Hangfire.Core

In this part, we will create several jobs:

Create file InternalGoatJob.cs

  public Task ExecuteRecurringJobAsync(string cronExpession,CancellationToken stoppingToken)
  {
    _recurringJobs.AddOrUpdate("internal-goat-recurring-job",
                               ()=>_goatService.RecurringExecuteAsync(stoppingToken), 
                               cronExpession);

    return Task.CompletedTask;
  }

  public Task ExecuteQueueJobAsync(CancellationToken stoppingToken)
  {
    _backgroundJobClient.Enqueue<GoatService>(x => x.ExecuteAsync(stoppingToken));
    return Task.CompletedTask;
  }

  public Task ExecuteQueueJob(CancellationToken stoppingToken)
  {
    _backgroundJobClient.Enqueue<GoatService>(x => x.Execute(stoppingToken));
    return Task.CompletedTask;
  }

Now we need to set up the Hangfire Dashboard.

GoatHangfire.Dashboard

 dotnet new worker -o GoatHangfire.Dashboard
 dotnet add package Hangfire
 dotnet add package Hangfire.SqlServer
 dotnet add package Microsoft.Data.SqlClient

What I appreciate about Hangfire is the Hangfire Dashboard. It's a built-in, web-based user interface that allows you to monitor, manage, and debug your background jobs. If you don't set any authorization, the dashboard is accessible only on localhost.

By default, the Hangfire Dashboard is accessible at "/hangfire". You can change this by passing a different route to

app.UseHangfireDashboard("/dashboard",
                         new DashboardOptions { Authorization = new[] { new AuthorizationAlwayTrueFilter(), }, });

The first argument to UseHangfireDashboard is the route where the dashboard will be accessible. In this case, it's "/dashboard".

The second argument is an instance of DashboardOptions. This is where you can specify options for the dashboard. In this case, an AuthorizationAlwayTrueFilter is used, which means the dashboard will be accessible without any authorization.

You can also set up SSO authentication for the Hangfire Dashboard by using the AuthorizationSsoFilter class.

Authorization

The AuthorizationAlwayTrueFilter class is a custom implementation of the IDashboardAuthorizationFilter interface. This class is defined in AuthorizationAlwayTrueFilter.cs.

public class AuthorizationAlwayTrueFilter : IDashboardAuthorizationFilter
{
    public bool Authorize(DashboardContext context)
    {
        return true;
    }
}

Connection to Hangfire

The Hangfire Dashboard is connected to Hangfire using the UseSqlServerStorage method. The connection string is retrieved from the configuration.

.UseSqlServerStorage(builder.Configuration.GetConnectionString("HangfireDbConnection"))

The connection string is defined in the appsettings.json file under the "ConnectionStrings" section.

"ConnectionStrings": {
    "HangfireDbConnection": "Server=127.0.0.1,1633;Database=hangfire;User=sa;Password=Your_password123;Trusted_Connection=false;Encrypt=false"
}

Add Endpoints in order to directly run/update jobs.

HostApplicationBuilder builder = Host.CreateApplicationBuilder(args);
builder.Services.AddHostedService<ExternalGoatJob>();

builder.Services.AddHangfire(configuration => configuration
    .SetDataCompatibilityLevel(CompatibilityLevel.Version_180)
    .UseFilter(new AutomaticRetryAttribute { Attempts = 0, })
    .UseSimpleAssemblyNameTypeSerializer()
    .UseRecommendedSerializerSettings()
    .UseColouredConsoleLogProvider() 
    .UseSqlServerStorage(builder.Configuration.GetConnectionString("HangfireDbConnection")));

Accessing the Dashboard

Once the application is running, you can access the Hangfire Dashboard at https://localhost:32793/dashboard.

Create/Update a Recurring Job with swagger:

As you can see, for external jobs, we have less information than internal jobs. Job => Could not resolve assembly ..... This is due to the fact that the job is not referenced in the dashboard project.

If you try to requeue an external job, you will get an error "System.IO.FileNotFoundException: Could not resolve assembly 'GoatHangfire.ExternalJob'."

Conclusion

In wrapping up our exploration of Hangfire, it's clear that this library offers a comprehensive solution for background processing in .NET Core applications.

The Dashboard is a response to my main objective. This built-in, web-based user interface provides a clear and detailed overview of all your background jobs, allowing you to monitor, manage.

Resource Consumption: Depending on the number of jobs and the frequency at which they are processed, Hangfire can consume significant system resources, especially if it's running in the same process as your web application.