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Peter Lorimer has built the ASPeKT AOP framework. This episode is sponsored by Uncall.

Show Notes:

Want to be on the next episode? You can! All you need is the willingness to talk about something technical.

Merry Christmas! This is the last day of the C# Advent. Make sure to check out all of the other great posts from 2017 and 2018. If you want to be involved next year, look for C# Advent 2019 author sign ups at the end of October 2019, and look for blog posts to start showing up on December 1st, 2019.

What is a background job?

A background job is some code that runs apart from the normal flow of your program. It could be run asynchronously and/or on another thread. As an ASP.NET MVC developer, I tend to think of it as any task that runs outside of an MVC action being invoked.

There’s two kinds of background jobs that I’m aware of:

  • Scheduled - a task that runs every N minutes, or every Y hours, etc. This is what I’m going to show in this post today. It’s great for making periodic checks, ingesting data from some other source, etc.

  • Fire and forget - Some other piece of code kicks off a process to run in the background. It doesn’t block the code (fire), and the code doesn’t wait for a response (forget). This is great for potentially time consuming operations like checking inventory, sending emails, etc, that you don’t need a user to wait for.

What you usually need to do to create background jobs

In my experience, I’ve seen background jobs take a few different forms.

  1. Separate Windows service (or Linux daemon, whatever). A console/service program that’s running in addition to your ASP.NET program. This works fine for scheduled jobs.

  2. Queueing mechanisms like Kafka or Rabbit. The ASP.NET program will put messages into these queues, which will then be processed by some other program. This is fine for fire-and-forget.

  3. Background jobs running within the ASP.NET process itself. In my experience, I’ve used Quartz.NET, which can run within the ASP.NET process. There’s also FluentScheduler (which I’ve not used, and doesn’t seem to come with database integration out of the box?)

With all these options in the past, I’ve experienced deployment difficulties. The wrong version of the service gets deployed, or isn’t running, or fails silently, or needs to be deployed on multiple servers in order to provide scalability/availability etc. It’s totally possible to overcome these challenges, of course. (I should also note that in my experience with Quartz.NET, I never used it in embedded form, and the last time I used it was probably 6+ years ago).

But if I just need a handful of background jobs, I’d much rather just make them part of the ASP.NET system. Yes, maybe this goes against the whole 'microservice' idea, but I don’t think it would be too hard to refactor if you decided you need to go that route. I solve my deployment problems, and as you’ll see with Hangfire (with Couchbase), it’s very easy to scale.

How hangfire works

You can find more details and documentation about Hangfire at Hangfire.io. Really, there are only three steps to setting up Hangfire with ASP.NET Core:

  1. Tell ASP.NET Core about Hangfire

  2. Tell Hangfire which database to use

  3. Start firing off background jobs

In Startup.cs, in the ConfigureServices method:

services.AddHangfire(x => x.UseCouchbaseStorage(configuration, "familyPhotos_hangfire"));

Then, in Startup.cs, in the Configure method:

app.UseHangfireServer();

I’m using Couchbase in this example, but there are options for SQL Server and other databases too. I happen to think Couchbase is a great fit, because it can easily horizontally scale to grow with your ASP.NET Core deployments. It also has a memory-first architecture for low latency storage/retrieval of job data. Generally speaking, even if you use SQL Server as your "main" database, Couchbase makes a great companion to ASP.NET or ASP.NET Core as a cache, session store, or, in this case, backing for Hangfire.

The configuration variable is to tell Hangfire where to find Couchbase:

var configuration = new ClientConfiguration
{
    Servers = new List<Uri> { new Uri("http://localhost:8091") }
};
configuration.SetAuthenticator(new PasswordAuthenticator("hangfire", "password"));

(In my case, it’s just running locally).

Steps 1 and 2 are down. Next, step 3 is to create some background jobs for Hangfire to process. I’ve created an ASP.NET Core app to assist me in the cataloging of all my family photographs. I want my application to scan for new files every hour or so. Here’s how I create that job in Hangfire:

RecurringJob.AddOrUpdate("photoProcessor", () => processor.ProcessAll(), Cron.Hourly);

Note that I didn’t have to implement an IJob interface or anything like that. Hangfire will take any expression that you give it (at least, every expression that I’ve thrown at it so far).

Step 3 done.

Hangfire is just a NuGet package and not a separate process. So no additional deployment is needed.

How do I know it’s working?

Another great thing about Hangfire is that is comes with a built-in dashboard for the web. Back in Startup.cs, in Configure, add this code:

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

I’m using my own HangfireAuthorization implementation because Hangfire only gives permission to local users by default.

Then, you get a nice dashboard right out of the box, showing you a realtime and history graph.

Hangfire dashboard

From this dashboard, you can also look at a more detailed history of what’s run and what’s failed.

Succeeded jobs

You can even kick off recurring jobs manually.

Recurring jobs

This is only the start

If you’re thinking about adding background jobs to your ASP.NET Core solution, why not give Hangfire a try?

Some more things for you to explore:

  • Scaling: every ASP.NET Core site that gets deployed with Hangfire that points to the same database will be able to process jobs too. As your ASP.NET Core site scales out, hangfire scales out with it. This is another reason that Couchbase is a good fit, because it’s also easy to scale out as your site grows.

  • Cloud: If you are deploying your site as an app service, note that Azure will shut down ASP.NET processes if they haven’t been used in a while. This means Hangfire will shut down with them. There are a couple of ways to deal with this. Check out the Hangfire documentation.

  • Retries: Hangfire will retry failed jobs. Design your background job code to expect this.

  • Hangfire Pro: The commercial version of Hangfire is called Hangfire.Pro, and it comes with some interesting looking batch capabilities. I’ve not needed any of this functionality yet, but for more advanced cases you might need this.

  • Couchbase: a NoSQL data platform that has a built-in memory-first cache layer, SQL support, text search, analytics, and more. There are lots of options for working with Couchbase in .NET. For this post, I used the Hangfire.Couchbase library (available on NuGet).

Podcast 107 - Season 3 Wrap

December 05, 2018 mgroves 0 Comments
Tags: podcast

Thank you for being a loyal listener of Cross Cutting Concerns. This is a very short episode, but stay tuned until the end of the episode for a little sneak peak at what's coming next year.

I've really enjoy making these shows, and I hope you find them useful!

I'll be back with new episodes in 2019.

In the meantime, there are a few things you can do to help support the show.

First, if you are using any podcast platform that allows reviews, especially iTunes, leaving a review is very helpful, and helps people find the show.

Second, I've started a new "feedback" page. You can submit ideas and vote on other's ideas. Go to crosscuttingconcerns.com/podcast and click on the LEAVE FEEDBACK button.

I'm especially interested in suggestions for future guests, your thoughts on the JavaScript game this year, and what topics you'd like to hear covered. More COBOL? Less JavaScript? More Nintendo emulation? Less ColdFusion? I want to know. This year was the best year yet, but I think next year will be ever greater with your help.

Third, please tell people about the show! Tweet, facebook, tell your coworkers.

Finally, I'm thankful for my sponsor this year, Smartsheet. Check them out at smartsheet.com/crosscuttingconcerns. I'm also thankful to all the great guests, I can't list them all, but I'm so grateful that I got to meet and hang out with all of you. I want to give special thanks to David Giard for being so supportive and inspirational. Be sure to check out his show Technology and Friends. I also want to give special thanks to Joe Ferg for creating some amazing music, make sure to check out all the excellent stuff he is creating at JoeFerg.com.

I'm thankful for each one of my listeners, and I hope you'll stay with me next year.

 

Last year's C# Advent was a success beyond anything I expected. I was worried that I wouldn't get enough sign-ups, but I ended up turning some people away. I was worried that people wouldn't get their blog posts done on time, but every single author delivered on time. I was worried there would be too much overlap in topics. There was a tiny bit, but every author's post had a unique, quality perspective, even if there was some overlap.

So, I'm doubling down this year! Each day of the Advent calendar will have up to TWO blog posts. That means that there is a maximum of FIFTY slots! So, tell your C# friends and let's fill up this calendar.

A little history: I heard about the F# Advent Calendar, a tradition that's been carried on since 2010 (2014 in English) and is still going strong in 2018. I think this is a great idea, and so I organized one for C#! (I asked Sergey Tihon for permission!). Other Advent calendars: C# Advent Calendar (in Spanish)Q# Advent Calendar.

So, I need you to write a C# blog post!

Here are the rules:

  1. Reserve a slot on Twitter (with hash tag #csadvent) or leave a comment on this post. You do not have to announce your topic until the day you reserve.
  2. Prepare a blog post (in English).
  3. Add a link in your blog post that links back to here, so that your readers may find the entire advent.
  4. Publish your blog post on the specified date. Your post must be related to C# in some way, but otherwise the content is completely up to you. I've posted a few ideas below to get your creativity flowing.
  5. Share your post on Twitter with hashtags #csharp and #csadvent

Below are all the slots, and who has claimed each date.

I will do my best to keep this up to date. The slots will be first come first serve. I also allowed last year's authors to get first crack. I have already claimed one of the December 25th slots for myself, but I can be persuaded to change if you really want that date.

DateClaimed byBlog Posts
Dec 1, 2018 Lukáš Lánský Steve Smith Namespacer: lightweight spin on architecture validation Double Dispatch in C# and DDD
Dec 2, 2018 Hilary Weaver-Robb Shahed Chowdhuri Can I Put All Of My Smoke Tests For A REST API In One Test? Yes! Your First Razor UI Library with ASP.NET Core
Dec 3, 2018 Bill Sempf Luis Antonio Beltran Insecure Binary Deserialization Azure Blob Storage with Xamarin.Forms
Dec 4, 2018 Tim Corey Matthew Jones How to Be a Great C# Developer Using Stopwatch and ContinueWith to Measure Task Execution Time in C#
Dec 5, 2018 James Hickey Calvin Allen Scalable Task Scheduling In .NET Core With Coravel Using .editorconfig in Visual Studio to create discoverable standards
Dec 6, 2018 Brant Burnett Isaac Levin A Restful Job Pattern For A C# Microservice Six Opinionated Tips to be a Better .NET Developer
Dec 7, 2018 Ryan Overton James Hickey Native API Access in Xamarin.Forms .NET Core Dependency Injection: Everything You Ought To Know
Dec 8, 2018 Carl Layton Shahed Chowdhuri Create Formatted Text Files With csvhelper Exploring .NET Core 3.0 and the Future of C#
Dec 9, 2018 Jeremy Sinclair Ian Russell Secure Data Access with IdentityServer4 and Xamarin Forms Expressing intent with value objects
Dec 10, 2018 James Curran Caleb Jenkins Here, There and Everywhere - A Simple Look at .NET Memory Model [?]
Dec 11, 2018 Andrew Lock Simon Timms Why is string.GetHashCode() different each time I run my program in .NET Core? Linked lists in C#
Dec 12, 2018 Ed Charbeneau Andres Paz Razor Components for a JavaScript-Free FrontEnd in 2019 Implementing a quantum simulator for Q# in C#
Dec 13, 2018 Amber Race Brian Jackett WireMock.Net Introduction to Calling Microsoft Graph from a C# .Net Core Application
Dec 14, 2018 Lee Englestone Daniel Oliver English Language Word Analysis With .NET OpenTracing and C#
Dec 15, 2018 Michael Eaton Kevin Griffin Exercises for Programmers – Weather Checker in C# Introduction to SignalR Streaming
Dec 16, 2018 Barret Blake Doug Mair Flow & Function Together Quick Introduction to C# Span
Dec 17, 2018 Gérald Barré (aka Meziantou) David Pine  Writing a Roslyn analyzer C# all the thing: .NET Core global tools
Dec 18, 2018 Duane Newman Caio Proiete Keeping Observable Collections Up To Date [?]
Dec 19, 2018 Jonathan Danylko Huzaifa Asif 10 More C# Extension Methods For The Holiday Season Create a custom middleware pipeline using .NET Core
Dec 20, 2018 Baskar Rao Eric Potter Testing .Net Core API using Auth0 with VS Tests The code changes in Roslyn between 7 and 8
Dec 21, 2018 Takayoshi Tanaka (vacated) Using Kubernetes readiness and liveness probes for health checks with ASP.NET Core 2.2 on OpenShift  
Dec 22, 2018 Jim Wilcox Chris Bohatka C# and WebAssembly Hit the Ground Running: Create a Starter Kit
Dec 23, 2018 Damian Łączak Chris Sainty An extension that I cannot code without. Blazor Toast Notifications using only C#, HTML and CSS
Dec 24, 2018 Chris Woodruff Gregor Suttie Getting the Most Out of Entity Framework Core - Part 1 Azure Blobs from C# and Visual Studio
Dec 25, 2018 Matthew Groves Calvin Allen Hangfire with ASP.NET Core C#, .NET, and Visual Studio - 2018 Year in Review

Alternates:

  • IF ALL FIFTY SLOTS FILL UP, please leave a comment or tweet with #csadvent anyway!
  • I will put you on this 'standby' list in case someone drops out or can't deliver their post in time.
  • Standby list:
    • Corstiaan Hesselink

Some ideas/topics to help inspire you:

  1. Blazor - now's your chance to experiment with writing C# for the browser
  2. Your latest open source contribution - show the community how you contributed and why
  3. Your favorite C# language feature - it doesn't even have to be a new feature, just blog about something you love about C#
  4. Introduce your favorite NuGet package / library. Even if it's a library you take for granted, not everyone has heard about it.
  5. How to avoid a pitfall you found with performance/memory/etc
  6. Integration/deployment of a C# application with Jenkins, Docker, Kubernetes, TeamCity, Azure, etc
  7. Write a "how to" for one of the many tools discussed in an episode of the Cross Cutting Concerns podcast
  8. Create a video tutorial and embed it in your blog post.
  9. Interview someone about C# and embed an audio player in your blog post.
  10. Implement a simplified example of a design pattern in C#

Thanks to everyone who is participating!

Matthew D. Groves

About the Author

Matthew D. Groves lives in Central Ohio. He works remotely, loves to code, and is a Microsoft MVP.

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