ASP.NET Core Web API custom formatters

ASP.NET Core does support out of the box JSON, XML, or plain text formatters based on the ACCEPT Header. In this post, I’ll explain how to specify other formatters and return them based on the ACCEPT Header. As an example, I use a CSV formatter to return a CSV formatter. A controller method returns the format based on the ACCEPT Header which is specified by the client. This can be very useful in cases where you need to export your data to Excel, and the use of more formats makes your application more accessible.

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HttpClient and HttpClientFactory in ASP.NET Core

With .NET Core 2.1 the HttpClientFactory is introduced. The HttpClientFactory is a factory class which helps with managing HttpClient instances. Managing your own HttpClient correctly was not so easy. The HttpClientFactory gives you a number of options for easy management of your HttpClient instances. In this post I’ll explain how to use the HttpClientFactory in your ASP.NET Core application.

Injecting a Scoped service into IHostedService

In our projects we are using IHostedService to run background processes. What I have seen is that when injecting a scoped service into the IHostedService you get a InvalidOperationException on startup. The first time you get this exception, it is takes some time to figure out what is going on. This blog post will help you to resolve the problem faster.

Access XML SOAP services in .NET Core and client certificates (SSL)

Only a few years back Windows Communication Foundation (WCF) was the way to do communication on the Microsoft platform based on SOAP protocol. Now a days new services are mostly build on top of Representational State Transfer (REST) Services. Sometimes you have to access a ‘legacy’ SOAP services for .NET Core. .NET Core has limited WCF support. In this blog post I’ll explain how to consume SOAP services form .NET Core.

Run scheduled background tasks in ASP.NET Core

In the previous blog post called background tasks with ASP.NET Core using the IHostedService Peter described how to use the IHostedInterface for background tasks. In this post, we continue on this subject and add some pointers on how to perform scheduled background tasks.

In many software projects, there are repetitive tasks; some do just repeat every x seconds after the last instance is finished but you might also have to run a task on a schedule like every 10 minutes. When building repeating or scheduled tasks there are many options on how to approach the scheduling and this approach can be influenced by a number of technical choices.

Building the scheduling yourself is an option when you do not want to add extra dependencies to your project, have full control or just want an extra technical challenge. An out of the box solution you can a look at Hangfire, Quartz.net, or an external service that does an http call every x seconds to trigger the task (something like Pingdom).

Upgrade ASP.NET Core and Entity Framework Core 2.0 to 2.1

In the past weeks we have upgraded our ASP.NET Core 2.0 project to 2.1. The main reason for the upgrade is using the latest signalr capabilities and hosted services. The issues we had are related to the features we use. In our case the upgrade encountered some minor issues. In this blog post I’ll show what we had to change and give some tips on how to upgrade.

WebHost CreateDefaultBuilder, what differs if you run in Development

When building ASP.NET Core 2 web applications, most projects are initializing Kestrel with the CreateDefaultBuilder. If you use this extension method to configure Kestrel, it is good to know what is set and what differs when you are running a Development configuration or any other configuration. In practice there are two differences. In this blog I’ll explain the two differences.

ASP.NET Core background processing with IHostedService

Many services need background processing. The ASP.NET Core 2.X IHostedService interface gives you an easy implementation skeleton to implement background processes. The Hosted Services are registered in the dependency injection at startup and started automatically. You do not have to do the pluming to get them started at startup. On shutdown you can implement a graceful shutdown. When running background processes there a few pitfalls to avoid. In this blog I’ll introduce the IHostedService and how to avoid common memory leaks when implementing the hosted service.

Cannot access a disposed object in ASP.NET Core when injecting DbContext

Working with ASP.NET core I have seen this error multiple times and can be hard to debug. The error can have multiple root causes. It can be a real pain to find the cause and it is sometimes fixed by only taking care of the symptoms. By finding the root cause, you can take the appropriate action in your code.

ASP.NET Core correct usage of ConfigureAwait with async/await

Lately we had a discussion on when to use ConfigureAwait(true) or ConfigureAwait(false) in ASP.NET Core 2. In the end most of the team, including me, had a faulty assumption on how to do this in ASP.NET Core. In this case ASP.NET Core is different from ASP.NET. Good to know if you have to decide on what to use in ASP.NET core.