WebHost CreateDefaultBuilder, what differs if you run in Development

Knowing the differences when you run your application in a Development environment

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.

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ASP.NET Core background processing with IHostedService

Run background processes with the IHostedService and how to inject your services with dependency injection

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

Find the root cause of what really happened to you disposable object.

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.

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Increase timeout Migrations Entity Framework Core

Use a different connection timeout when running your migrations with EF Core.

Sometimes a migration takes more time then your default timeout of your database connection. In such a case you do want to increase the timeout for the migration to be able to complete, but you do not want to change the timeout for your normal operations.
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Add Index with Include Entity Framework Core

This post explaines how to add index to EF Core with extra columns included from code.

When creating indexes with code first migrations in Entity Framework Core you can create an index on a table by adding the following to your DbContext:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<table>() 
        .HasIndex(t =&gt; new { t.Column1, t.Column2}); } 

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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.

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Cross process Application Insights with Multi-Role Application Map

Use Multi-Role Application Map to monitor cross process dependencies

When using Application Insights to monitor your Microservices environment, it would be nice to track calls over process boundaries. Application Insights has a preview for Multi-Role Application Maps. This enables you to visualize the dependencies over multiple processes and name the different processes. In this blog posts I will explain how to use Multi Role Application Maps, give you different process names and add dependency tracking into your application. Continue reading “Cross process Application Insights with Multi-Role Application Map”

Implement Pessimistic Concurrency in Entity Framework Core

ConcurrencyIn a scenario where we were using SQL server as a queue, before publishing events to external queues, we wanted the data to be processed only once and in order, even with multiple processors for failover. When reading from the table we wanted to lock the records and block other processors from reading those records, while being processed. This is called Pessimistic Concurrency, unfortunately Entity Framework Core does not support this out of the box. To realize Pessimistic Concurrency you need to write your own SQL queries directly on the database (The solution is database type bound, in this case Microsoft SQL server). This blog post will show how it can be accomplished.
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Get your web application errors into Slack

Get your devops going by integrating your application into your team communication tooling.

bugbotTo get more out of Slack and your team, you can integrate Slack with your application. Integrating with slack is done with webhooks. In this sample I use a Incoming Webhook to post the messages from the application to slack. By adding a GlobalExceptionFilter to you .Net Core web application, you can get all exceptions that are not handled in your web application.
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Application Shutdown in ASP.NET Core with IApplicationLifetime

Learn how to gracefully handle Application Shutdown in ASP.NET Core by looking at the handling of flushing the application insights messages when asp.net core exits

When running an ASP.NET Core web application, there are cases when you need to do some logic when the application stops. An example: you are logging and have to flush the last message to the log (Application Insights). In that case you need can add an event in the Configure method. In this post I show a short example of how doing this.
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