Here’s a summary of what’s new in this preview release:

• Improved ASP.NET Core debugging experience
• Servers & middleware
  • IHttpSysRequestTimingFeature
  • SNI hostname in ITlsHandshakeFeature
  • IExceptionHandler
• Blazor
  • New Blazor Web App project template
  • Blazor router integration with endpoint routing
  • Enable interactivity for individual components with Blazor Server
  • Improved packaging of Webcil files
  • Blazor Content Security Policy (CSP) compatibility
• API authoring
  • Support for generic attributes
• SignalR
  • SignalR seamless reconnect
• Native AOT
  • Support for AsParameters and automatic metadata generation in compile-timed generated minimal APIs
• Authentication and authorization
  • Authentication updates in ASP.NET Core SPA templates
  • New analyzer for recommended AuthorizationBuilder usage
   

ASP.NET Core Identity is Microsoft’s membership system widely known to .NET developers for managing application users. 

- TimeSeries.Guru is a column-oriented Time Series Database as a Service
- MonetDB is an Open Source column-oriented database
- Wikipedia 

Build a Complete Blog App with Blazor Server - Step-by-Step Tutorial from Scratch by Abhay Prince

You will learn about fundamentals of Blazor Server, Routing, Shared Reusable Components, Custom Authentication, EF Core Code First, Passing data from parent to child components and vice versa, Passing events from child to parent components, Forms validations and submissions, styling components, using javascript with blazor. third party components integration with blazor, blazor lifecycle events, authentication and authorization in blazor server, programtically navigating between component pages, multiple routes paths for single component page, dynamic routes and getting data from routes, authorized view and much more... 

var cors = new EnableCorsAttribute("*", "*", "*");
config.EnableCors(cors);
config.MessageHandlers.Add(new PreflightRequestsHandler());

public class PreflightRequestsHandler : DelegatingHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (request.Headers.Contains("Origin") && request.Method.Method == "OPTIONS")
        {
            var response = new HttpResponseMessage {StatusCode = HttpStatusCode.OK};
            response.Headers.Add("Access-Control-Allow-Origin", "*");
            response.Headers.Add("Access-Control-Allow-Headers", "Origin, Content-Type, Accept, Authorization");
            response.Headers.Add("Access-Control-Allow-Methods", "*");
            var tsc = new TaskCompletionSource<HttpResponseMessage>();
            tsc.SetResult(response);
            return tsc.Task;
        }
        return base.SendAsync(request, cancellationToken);
    }
}

jQuery.support.cors = true;