Microsoft.PowerPlatform.Dataverse.Client and ClientSecret AuthType

.NET Core 3.1 is what I consider a good starting point if you plan to create a new project based on .NET Core, it's LTS (until end of 2022) and if you developed only with .NET Framework before, I usually suggest this version.

I know .NET 5.0 has been released for some months now but for what I am describing here it's not important, if you wish you can use this version.

If you are a developer and in the last years you worked with Dynamics CRM/CDS/Dataverse you probably know this NuGet package:
Microsoft.CrmSdk.XrmTooling.CoreAssembly

It's the package we usually install when we need to connect to Dataverse, it works but requires .NET Framework 4.6.2 or onward. It works also with ClientSecret AuthType, if you have this kind of connection string

AuthType='ClientSecret'; ServiceUri='https://mywonderfulorg.crm.dynamics.com';
ClientId='00000000-0000-0000-0000-000000000000'; ClientSecret='MyWonderfulClientSecret';

or if you are using Username & Password you may have something like this

AuthType='Office365'; Url='https://mywonderfulorg.crm.dynamics.com';
Username='username@mywonderfulorg.onmicrosoft.com'; Password='MyWonderfulPassword';

In your code you can connect with few lines:

CrmServiceClient service = new CrmServiceClient(connectionString);
WhoAmIResponse whoAmIResponse = (WhoAmIResponse)service.Execute(new WhoAmIRequest());
Console.WriteLine($"Connected with UserId: {whoAmIResponse.UserId}");

CrmServiceClient comes from the namespace Microsoft.Xrm.Tooling.Connector.

What if we want to use .NET Core? The NuGet package to use is currently in public preview:
Microsoft.PowerPlatform.Dataverse.Client

You can use this package also with .NET Framework and .NET 5.0 but the main reason is the compatibility with what we call .NET Core (and if you still want to say something like "but with .NET 5.0 we can bla bla bla" fine for me, also with .NET Core is possible to use .NET Framework packages but we would make the executable only compatible with Windows, I never suggested that kind of path but it's a possibility).

This package is not compatible with the Username & Password authentication, as stated inside the description: Note: that only OAuth, Certificate, ClientSecret Authentication types are supported at this time.

Meaning it's also a good time to move away from old forms of authentication.

Assuming you have a connection string with the ClientSecret AuthType how would our code changes? Just a type:

ServiceClient service = new ServiceClient(connectionString);
WhoAmIResponse whoAmIResponse = (WhoAmIResponse)service.Execute(new WhoAmIRequest());
Console.WriteLine($"Connected with UserId: {whoAmIResponse.UserId}");

ServiceClient comes from the namespace Microsoft.PowerPlatform.Dataverse.Client, that is also the name of the package, so make sure you are using it.

Hopefully next time I will remember that is called ServiceClient and not CrmServiceClient, DataverseClient or PowerPlatformClient, types I tried before checking what was inside the package.