BlazorSample-BootProgress

Sample of client-side Blazor with an improved boot up sequence

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This Blazor sample shows how to improve the screen shown during "boot up" of a client-side Blazor application to provide more pleasant user experience with more user feedback about its progress.

You can see this example running here:

• http://bootprogress.blazorsample.bkkr.us.

The sample builds on various other contributions. For starters, we add a small progress animation based on SpinKit to improve the aesthetics.

Next, we adapt the enhancements in this article that describes a technique for intercepting calls to load the initial DLL assemblies during Blazor's stock boot up process. The original intent is to change the visible DLL file extensions for those scenarios where they are blocked from loading, for example by corporate firewalls.

We build on this technique to provide load status to the user as each DLL assembly is loaded, to give the user some feedback as to the overall boot up progress.

Artificial Delay

Because the stock Blazor client sample (dotnet new blazor) doesn't have many DLLs to load, the boot up screen may actually run relatively quickly (defeating the need for this technique), but you'll find this useful in larger, more real-world applications that may have many more and larger CLR assemblies to load.

In order to simulate what you would actually experience with a larger set of assemblies, this sample has an artificial load delay of 200ms per DLL built in. And you can adjust this value or disable it completely with some URL query parameters (see below).

Query Parameters

You can adjust various settings of this sample by providing query parameters to play around with the behavior:

• dll_min - the minimum progress bar value, defaults to 0
• dll_max - the maximum progress bar value, defaults to 25 which is the number of DLLs loaded by this example
• dll_val - the starting progress bar value, defaults to 0 before any DLLs are loaded
• dll_msg - the initial progress message, defaults to Loading application... and will get replaced as each DLL is loaded
• xhr_send_delay_factor - if > 0, will enable artificial send delay by the factor number of milliseconds per DLL, defaults to 100
• xhr_send_abort_count - if > 0, will abort the boot process after that number of DLLs have loaded, useful to take a snapshot of the progress bar working, defaults to 0