Using a scoped service inside a HostedService

When trying to resolve a scoped dependency inside a HostedService, the runtime returned the following error message:

System.InvalidOperationException: Cannot consume scoped service ‘IScoped’ from singleton ‘Microsoft.Extensions.Hosting.IHostedService’.

The problem is that the IHostedService is a singleton and is created outside a dependency injection scope. Trying to inject any scoped service(e.g.  an EF Core DbContext) will result in the error message above.

To solve this problem you have to create a dependency injection scope using the IServiceScopeFactory. Within this scope you can use the scoped services:

IdentityServer 4 - CORS

If an endpoint is called via Ajax calls from JavaScript-based clients, CORS configuration is required.

This can be done by setting the AllowedCorsOrigins collection on the client configuration. IdentityServer will consult these values to allow cross-origin calls from the origins.

Remark: Be sure to use an origin (not a URL) when configuring CORS. For example: https://foo:123/ is a URL, whereas https://foo:123 is an origin.

MassTransit–Batch Message Consumption

A lesser known feature inside MassTransit is the support of batch messages. This can be a really nice feature if you want to combine a batch of high-volume smaller messages into a single atomic consumer.

How does this work?

MassTransit will combine multiple messages into a single consume by specifying a window, such as a message count (batch size), time period, or a combination of both.

There are 2 configurable limits:

• Size: A limit specifying the maximum number of messages which can fit into a single batch will trigger once that many messages are ready to be consumed. The batch size must be less than or equal to any prefetch counts or concurrent message delivery limits in order reach the size limit.

• Time: A limit specifying how long to wait for additional messages from the time when the first message is ready, after which the messages ready within that time are delivered as a single batch. The time limit should be well within the lock time of a message, including enough time to process the batch.

Batch configuration

To use the batching functionality, configure an extra receive endpoint and use the Batch method to configure the endpoint:

Batch consumption

The message batch is delivered as an array to the consumer, so that the existing behavior is maintained for middleware, factories, etc. An additional context is available on the payload, which can be used to discover details related to the batch. Instead of receiving a single message you get a Batch<T> of messages:

Remark: This feature is experimental.  Be sure to configure the transport with sufficient concurrent message capacity (prefetch, etc.) so that a batch can actually complete without always reaching the time limit.

Azure DevOps - Kanban board limits

Got a question from a customer about the Kanban board in Azure DevOps Server:

I noticed that on the Kanban board on the first and last column only a limited number of work items are shown. Is this something that can be configured?

Quick answer: no.

To limit the number of items on the board, the first and last column of your kanban board will only show 20 work items. To see more work items you need to use the Show more items link in the bottom.

ASP.NET Core 3.0 - Enable Authentication

Quick tip for anyone using ASP.NET Core 3.0 (especially when you did an upgrade from ASP.NET Core 2.x); if you want to enable authentication don’t forget to add the correct middleware. You need both UseAuthentication and UseAuthorization:

In earlier versions of ASP.NET Core, authorization support was provided via the [Authorize] attribute. Authorization middleware wasn't available. In ASP.NET Core 3.0, authorization middleware is required(!). Therefore the ASP.NET Core Authorization Middleware (UseAuthorization) should be placed immediately after UseAuthentication.

Add the UseAuthorization and UseAuthentication methods AFTER the UseRouting() but BEFORE the UseEndpoints():

A DefaultPolicy is initially configured to require authentication, so no additional configuration is required.

ElasticSearch–Decrease the monitoring data

Quick tip to prevent the monitoring index to get out of control:

To decrease the amount of data of the ElasticSearch monitoring you can change the _cluster settings

More information: https://www.elastic.co/guide/en/elasticsearch/reference/current/monitoring-settings.html

Azure DevOps–How to change the default iteration?

After upgrading to Azure DevOps 2019, I got a question from a customer asking how to change the default iteration used when creating new work items. By default the current iteration is used. If you are creating user stories, this is probably not what you want as these user stories should first be analyzed, groomed, … before they can be planned inside a specific iteration/sprint.

Fortunately this is something that can be changed easily at the team level:

• Click on the Show Team Profile  icon on the Kanban board:

• Click on Team settings:

• Go to Iterations and Areas:

• Click on Iterations:

• Now you change the default iteration how you want: