Alethic.Node.AspNetCore 1.0.1-pre.25

Alethic.Node.AspNetCore

Serve a JavaScript application's pages from ASP.NET Core, rendered on Node.js embedded in the process (Alethic.Node). Published as Alethic.AspNetCore.Node through 0.3.

dotnet add package Alethic.Node.AspNetCore
dotnet add package Microsoft.JavaScript.LibNode.linux-x64    # the native runtime: one per platform you deploy to

Use

builder.Services.AddNodeEnginePool(o => o.EngineCount = 2);

var app = builder.Build();
app.UseStaticFiles();
app.UseRouting();                      // explicit, or the fallback endpoint outruns static files

app.MapNodeFetchHandler(o =>
{
    o.Module = NodeModuleSource.FromFile("ssr/app.cjs");
    o.Environment["ApiBaseUri"] = "http://api.internal:8080/";
});

app.Run();

app.cjs is a CommonJS bundle whose default export has a fetch(request, env, ctx) function returning a Response, or is one; Alethic.Node.Http says what it sees. The module loads on every engine at startup. RequestBody and ResponseBody are Streamed unless set to Buffered.

An endpoint per route

MapNodeFetchHandler mounts one fallback endpoint. For an endpoint per route, write an INodeRouteProvider that reads the application's own router, and pass it with the handler:

sealed class MyRouteProvider(NodeEnginePool pool, NodeModuleSource module) : INodeRouteProvider
{
    public Task<IReadOnlyList<RenderRoute>> GetRoutesAsync(CancellationToken cancellationToken = default) =>
        pool.RunAsync(module, exports => { /* read the routes out, as RenderRoutes */ }, cancellationToken);
}

app.MapNode(new FetchRequestHandler(pool, new() { Module = module }), new MyRouteProvider(pool, module));

A RenderRoute has a URLPattern Pattern (/parks/:parkRef), an Id that names the endpoint, and a RenderMode: Server, Prerender, or Client, which is not mapped. MapNodeOptions.ConfigureEndpoint sees each endpoint, for caching or authorization by route; FallbackPattern is the fallback, or null for none.

INodeRequestHandler (PrepareAsync, HandleAsync) is the seam for an application whose server protocol is not a fetch handler.

Constraints

• Set EngineCount to the cores the process may use; a container reports the host's.
• Modules are CommonJS, bundled, without code splitting. A rebuilt bundle needs a restart.
• Module state is shared by every render on an engine.
• A streamed response cannot change its status after its first byte.