ASP .Net Core SPA Templates

© Instil Software 2017
October 2017
eamonn.boyle@instil.coeamonn.boyle@instil.cogarth.gilmour@instil.co | eamonn.boyle@instil.co
ASP .NET Core
New SPA Templates

• I want new people on-boarded as quickly as possible
• I want to be able to add new features easily
• I want computers to do most of my work for me
• I don’t want the headache and hassle of bugs
Who am I?

Release Notes
• Razor Pages
• Single ASP .NET Core & EF Core meta-package
• Microsoft.AspNetCore.All
• Uses the Runtime Store
• Minor API Changes
• Logging, Configuration, WebBuilder
• Major API Changes
• Authentication, Identity, WebListener-> Http.sys
• New Single Page Application (SPA) Templates
• React [+ Redux], Angular and more
• Major Kestrel Updates – Internet Facing Supported
• Razor Pre-compilation
• And more…
ASP .NET Core 2.0

Release Notes
• Razor Pages
• Single ASP .NET Core & EF Core meta-package
• Microsoft.AspNetCore.All
• Uses the Runtime Store
• Minor API Changes
• Logging, Configuration, WebBuilder
• Major API Changes
• Authentication, Identity, WebListener-> Http.sys
• New Single Page Application (SPA) Templates
• React [+ Redux], Angular
• Major Kestrel Updates – Internet Facing Supported
• Razor Pre-compilation
• And more…
ASP .NET Core 2.0

Web Applications originally relied heavily on server side rendering:
Pros
• Templating frameworks easy for basic content
• Encapsulates business logic
• Small initial downloads for user/browser
• Works well with SEO
Cons
• Limited user experience -> Page Refreshes
• Over time, more data transferred – feels slower
• Heavy load on server
Server Side Rendering

The Single Page Application Concept
Service A
Service B
Service C
Single Page
Application
JSON
JSON
JSON
Web Server
Static Files
HTML, CSS, JS
We’ve moved to rich client-side experiences
• AJAX + jQuery and then on to UI frameworks –
Angular, React, Vue…..

Pros
• Separation of Concerns – Client-Server
• Very rich UX
• Only data transferred during interaction
• Lower load on server
• Easy deployment – static files
Cons
• Slow initial load – vendor download
• Does not play well with SEO
• Complex build mechanism
• Complex content definition
Single Page Application (SPA)

Foundations of Front End
“JavaScript is the VM of the web”
Douglas Crockford

The Evolution of JavaScript Frameworks
Angular 2/4
React
Angular 1DojojQueryManual
Scripting
HTML

Like a kid in a candy store…

Module Counts
http://www.modulecounts.com/
npm Package Count 
532,293
https://www.statista.com
Programmers in the UK 
292,000

TypeScript (aka TS) is a superset of JavaScript
• Created by Anders Hejlsberg at Microsoft
• Released as an open source project (Apache 2 License)
The language is transpiled into JavaScript
• The compiler is written in TS and runs on top of Node.js
• It can be used for both client and server side applications
Programming in TypeScript allows you to:
• Use the language features defined in ECMAScript 2015
• Add type declarations to variables, parameters etc…
• Make use of more advanced features like generics
Introducing TypeScript

JavaScriptServices is a series of packages for using client-side technologies
• Microsoft.AspNetCore.NodeServices
• Microsoft.AspNetCore.SpaServices
• Microsoft.AspNetCore.SpaTemplates
Useful when
• Run JavaScript on the server
• Use a SPA framework or library
• Build client-side assets with Webpack
JavaScriptServices

React and Angular templates are now included as part of .NET Core SDK 2.0
More templates can be installed via:
“dotnet new --install Microsoft.AspNetCore.SpaTemplates::*”
SpaTemplates
Templates Short Name
----------------------------------------------------------------
Console Application console
Class library classlib
Unit Test Project mstest
xUnit Test Project xunit
ASP.NET Core Empty web
ASP.NET Core Web App (Model-View-Controller) mvc
ASP.NET Core Web App razor
ASP.NET Core with Aurelia aurelia
ASP.NET Core with Knockout.js knockout
ASP.NET Core with Vue.js vue
ASP.NET Core with Angular angular
ASP.NET Core with React.js react
ASP.NET Core with React.js and Redux reactredux
ASP.NET Core Web API webapi

A TypeScript based web app platform
• Open source – led by team at Google
• Replaces AngularJS
• Provides services for UI, communication, DI etc
UI decomposed into components
• Follows an MVC pattern
• HTML for the View – annotated with special directives
• Component localised CSS for styling
• TypeScript for component Code Behind
• Augmented with other services, model etc.
Angular
@Component({
selector: ‘app-menubar',
templateUrl: ‘./menubar.component.html’
styleUrls: [‘./menubar.component.css’]
})
export class FetchDataComponent {
<h1>This is a HTML file</h1>
<app-menubar></app-menubar>

React is a front end UI framework
• Open source – led by Facebook
• Unlike Angular, it focuses only on UI
• Some libraries are commonly paired e.g. Redux
UI decomposed into components
• Defined completely in code
• Components define a ‘render’ method
• This returns a component tree
• JSX makes creating objects like writing HTML
React
export class Weather extends React.Component {
constructor() {
super();
}
public render() {
return <div>
<h1>This is JSX</h1>
<WeatherTable></WeatherTable>
</div>;
}
}

Comparing Angular 4 & React.js
Angular React
UI built using non-standard expressions
and directives in HTML
UI built using pure JavaScript
(though uses transpiled JSX)
Two way binding Unidirectional data flow
Decouples view from state State and view coupled
Performance impacts with complexity Fast due to data model
More complete framework
Many services e.g. REST, Browser etc
Only the view library
Angular 4 is TypeScript Pure JavaScript**
Google Facebook

NodeServices allow us to run JavaScript easily from within .NET code
• Runs Node.js in the background
• Uses an async API
• Can easily pass parameters, return results and catch errors
NodeServices

module.exports = function(callback, name) {
if (!name) {
callback("Error - no name provided", "Value not used");
}
else {
callback(null, "Hello " + name);
}
}
Node/HelloWorld.js
Invoking JavaScript from Within C#

[Route("api/[controller]")]
public class NodeController : Controller {
private readonly INodeServices nodeServices;
public NodeController(INodeServices nodeServices) {
this.nodeServices = nodeServices;
}
[HttpGet("HelloWorld/{name?}")]
public async Task<string> GetHelloWorld(string name) {
try {
return await nodeServices.InvokeAsync<string>("Node/HelloWorld", name);
}
catch (NodeInvocationException e) {
return "Caught error from Node - " + e.Message;
}
}
}
NodeController.cs
Invoking JavaScript from Within C#

Makes developing Single Page Applications with a .NET backend easier
• Builds upon NodeServices where Node.js is required
• SpaServices allows the development of the two to be more aligned
• Single server providing content and services
We can keep our backend services and client side projects separated
• Clear separation of client/server
• Optimised workflows
• Separate tooling
• Seaparate teams
SpaServices

Provides useful features such as:
• Server-side prerendering
• Webpack Dev Middleware & Hot Module Replacement
• Routing helpers
What you will need:
• Node version 6+
• ASP .NET Core 2.0
SpaServices

Server Side Rendering  Client Side Rendering  Universal / Isomorphic
Now universal or isomorphic applications are desirable
• JavaScript rendering on client and server
• Compromise between both worlds
• Popular client side frameworks offer support – Angular, React….
Pros
• Very rich UX
• Fast initial load with prerendered content
• Only data transferred during interaction
• Same technology used throughout
• Works well with SEO
Server Side Prerendering

SpaServices helps with server side prerendering
• Tag helpers within Razor for easy integration
The PrerenderTagHelper provides tag helpers to load prerendered content
• ‘asp-prerender-module’ – run a specified JavaScript file that does pre-rendering
• The script has a defined structured
• Uses elements from ‘aspnet-prerendering’ package
• ‘asp-prerender-data’ – pass data into the prerender script
Server Side Prerendering
<app asp-prerender-module="ClientApp/dist/main-server">Loading...</app>
<script src="~/dist/vendor.js" asp-append-version="true"></script>
@section scripts {
<script src="~/dist/main-client.js" asp-append-version="true"></script>
}
Index.cshtml

Webpack allows you to write your code in a modular, well-designed and scalable
way while still reducing runtime communication (fewer and smaller requests)
Webpack Dev Middleware

The Webpack Dev Middleware recompiles the client code while running
• Code watched and rebundled
• With Hot Module Replacement, the browser page is automatically reloaded
Enabling the Webpack Dev Middleware
public void Configure(IApplicationBuilder app, IHostingEnvironment env) {
if (env.IsDevelopment()) {
app.UseDeveloperExceptionPage();
app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions {
HotModuleReplacement = true
});
}
else {
app.UseExceptionHandler("/Home/Error");
}
Startup.cs

We have routing on the server and internal within the SPA
Routes not known to the server should resolve to the SPA
• Routes that look like static files (extensions) will not resolve to the SPA
Routing Helper
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
routes.MapSpaFallbackRoute(
name: "spa-fallback",
defaults: new { controller = "Home", action = "Index" });
});
Startup.cs

• The SPA templates provide quick solution for ASP .NET Core
• A few commands and you have a functioning app you can expand
• Keeps everything in one place
• Good example of desired build properties
• Optimised bundling
• Watch and Hot Module Replacement
• Prerendering for faster initial page loads
But…
• Tooling is currently sub-optimal compared to separate projects
• There are better SPA centric workflows
• E.g. Angular CLI + WebStorm / Visual Studio Code
Summary

ASP .Net Core SPA Templates

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