Configuring Lazy Loading @ Server

The following nuget package includes everything you need to support lazy loading on Blazor Server and Prerendering.

It can be installed by adding the following line inside the host csproj:

<PackageReference Include="BlazorLazyLoading.Server" Version="1.2.0" PrivateAssets="all" />

It will also require to be initialized from Startup.cs by adding the following lines:

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddLazyLoading(new LazyLoadingOptions
        {
            ModuleHints = new[] { "ModulesHost" }
        });
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        // ideally after calling app.UseStaticFiles()
        app.UseLazyLoading(); // serves DLL and PDB files as octet/stream
    }
}

LazyLoadingOptions

• ModuleHints

  In order to find the _lazy.json manifest files and DLLs, you need to specify at least an entry-point to a lazy module. This must be done by passing the "known modules" as string.

  Specifies a list of Module Names (hints) to:

  • Download DLLs from them
  • Use their manifest to locate lazy resources

• UseAssemblyIsolation

  Serverside Blazor has a small disadvantage: by default, the loaded assemblies are in the same context for every user. If you have a static field in them, the value will be shared accross all SignalR connections. If this happens, it can introduce weird bugs and massive scalability issues (it could also happen with a nuget package using a static field internally).

  To avoid these issues, BlazorLazyLoading introduces full assembly isolation by creating a Scoped AssemblyLoadContext. Unless you really know what you are doing, it is recommended to NOT turn this off.

  default: true Configures assembly isolation level. Do NOT set this to 'false' unless you want to share 'static' fields between users.
  Keeping this enabled ensures that the server can be scaled horizontally.