Cross-Plattform-Serveranwendungen mit ASP.NET Core

Cross-Plattform-Serveranwendungen
ASP.NET Core
Manuel Rauber
@manuelrauber
Software Architect

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The guy who’s talkin’
Software Architect @ Thinktecture AG
! [email protected]
" @manuelrauber
# https://manuel-rauber.com
Microsoft MVP
Manuel Rauber
ASP.NET Core

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Target Architecture
.NET Standard & .NET Core
ASP.NET Core MVC & Web APIs
EntityFramework Core
ASP.NET Core
Talking Points

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Time Doing
14:00 – 15:30 Part I
15:30 – 16:00 ☕ & "
16:00 – 17:30 Part II
ASP.NET Core
Timetable

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Overview
Lightweight service-based architecture
Functional services with dedicated interfaces
Use other services, like database or file system
(JSON-based) HTTPS Web APIs
Application push services via WebSocket
SignalR
Socket.io
ASP.NET Core
Target Architecture
HTTP HTTPS WebSocket
Service A Service B Service C
Web APIs
(ASP.NET, Node.js, …)
HTML5-Application
(Single-Page Application)
Web Cordova Electron

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“Behind the scenes”
Functional services with dedicated interfaces
Strict REST services do not model real world
Better: Design interfaces according to use case
Single Web API can use multiple backend services
(JSON-based) HTTPS Web APIs
Embraces usage of common denominator
Content Negotation
HTTP Status Codes
Resources are mapped to URLs
Lightweight & scalable
ASP.NET Core
Target Architecture
HTTP HTTPS WebSocket
Service A Service B Service C
Web APIs
(ASP.NET, Node.js, …)
AuthN & AuthZ
Client

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The new cool kid in town
ASP.NET Core
.NET Standard

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Application Models & Libraries
ASP.NET Core
.NET today
https://blogs.msdn.microsoft.com/dotnet/2016/09/26/introducing-net-standard/

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Challenges
Mastering different kind of base class libraries
Hard to reuse skills
Common denominator needed for code reusage
Hard to reuse code
Fiddling with a lot of interfaces
”Having fun with retargeting PCLs” J
Implementation needed on each platform
ASP.NET Core
.NET today

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Common denominator – Flashback 2014
ASP.NET Core
.NET today
Platform Code
Interfaces
All others:
Shared code with
platform switches

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One library to rule them all
ASP.NET Core
.NET tomorrow

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Benefits
One base library to learn, not one per .NET platform
Easy code reuse due to a bigger API surface area
.NET standard can be updated without having all platforms to be updated
Faster and independent update cycles
ASP.NET Core
.NET tomorrow

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What exactly is it?
.NET Standard is an open source specification: https://github.com/dotnet/standard
Represents a common set of API to be implemented by all .NET platforms
.NET Standard will replace PCLs
.NET Standard 2.0 will be released in Q3 2017
ASP.NET Core
.NET Standard
“.NET Standard solves the code sharing problem for .NET developers across all
platforms by bringing all the APIs that you expect and love across the
environments that you need: desktop applications, mobile apps & games, and
cloud services.”
- Immo Landwerth

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2.0
Differences to PCLs
Portable Class Libraries .NET Standard
ASP.NET Core
.NET Standard
Profile A
Profile B Profile C
Intersection Profile: Possible Platform targets
…
…
1.1
1.0
Higher versions are backwards
compatible to lower versions.

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Versioning
Additive: Higher versions incorporate all APIs from previous versions.
There are no breaking changes between versions
Immutable: After shipping, the version is frozen
ASP.NET Core
.NET Standard

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Versioning
ASP.NET Core
.NET Standard
https://github.com/dotnet/standard/blob/master/docs/versions.md

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Versioning
Higher version
more capabilities
more APIs
higher code reuse
less platform support
Lower version
less capabilities
less APIs
(maybe) lower code reuse
better platform support
ASP.NET Core
.NET Standard

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Targeting
Represented by NuGet package NetStandard.Library containing assembly netstandard.dll
in fact: everything’s a NuGet package within the new .NET Standard world
Build Time
.NET Standard bridges references to existing .NET Framework and PCL assemblies
via type forwarding
Run Time
Each platform provides an implementation for netstandard.dll that
type forwards to its own implementation
ASP.NET Core
.NET Standard 2.0

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Targeting
ASP.NET Core
.NET Standard 2.0

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Targeting @ Build Time
ASP.NET Core
.NET Standard 2.0
Your .NET
Standard-based
Class Library
.NET Framework
or PCL
netstandard.dll
mscorlib.dll
netstandard!Object
mscorlib!Object
Different Type
Identities
Type Forwarding
https://www.slideshare.net/terrajobst/net-standard-under-the-hood

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Targeting @ Build Time
ASP.NET Core
.NET Standard 2.0
Your .NET
Standard-based
Class Library
.NET Framework
or PCL
netstandard.dll
mscorlib.dll
Type Forwarding
mscorlib.dll
mscorlib.dll
Framework
Assemblies

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Targeting @ Run Time
ASP.NET Core
.NET Standard 2.0
Your .NET
Application
Framework
Assemblies
Your .NET
Standard-based
Class Library
netstandard.dll
Type Forwarding

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Platform-specific APIs
.NET Standard (mostly) contains APIs that run everywhere
A small subset will throw PlatformNotSupportedException
e.g. Registry, Reflection Emit, Windows Identity
ASP.NET Core
.NET Standard
Includes documentation, tests and code

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Platform-specific APIs
Conditional compilation
VS 2017 provides information about type availability
IDE Tool
Roslyn Analyzer to find problematic APIs
https://github.com/terrajobst/platform-compat
ASP.NET Core
.NET Standard
#if NETSTANDARD1_3 || NETSTANDARD1_4
var code = TypeCode.Boolean;
#endif

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Summary
Simple, yet powerful idea for creating cross-platform-targeting .NET libraries and applications
Good and growing API support
No breaking changes between versions
.NET Standard 2.0 (Q3 2017) brings compatibility with existing .NET Framework libraries
Using platform code could shrink targeting platforms
Targeting platform specific APIs could result in an error or conditional compilation
ASP.NET Core
.NET Standard

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From specification to implementation
ASP.NET Core
.NET Core

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Overview
.NET Core is an open source implementation of the .NET Standard specification:
https://github.com/dotnet/core
Runs on Linux, macOS and Windows
CLI tools available
Supports C# and F# (VB.NET is coming)
Compatible to .NET Framework, Xamarin and Mono (due to .NET Standard)
Fully supported by Microsoft (LTS support three years after GA)
ASP.NET Core
.NET Core

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Deployment
Offers flexible deployment possibilities
included within the app (self-contained deployments)
multiple versions can be installed side-by-side (framework-dependent deployments)
can be installed per user or machine-wide
Cloud-ready
ASP.NET Core
.NET Core

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Application Models
Shipped with .NET Core
Console Applications
Built on top of .NET Core
ASP.NET Core
Windows Universal Platform
Xamarin.Forms
ASP.NET Core
.NET Core

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IDEs
ASP.NET Core
.NET Core
VS 2017
VS Code JetBrains Rider
VS for Mac

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Use case depending alternatives
Node.js
JavaScript, TypeScript, CoffeeScript, …
Restify, Express, Koa.js
SequelizeJS, ORM
Node Package Manager, YARN
Java
Jersey, RESTful WebServices
Hibernate, ORM
Maven, Package Management
Ruby, Python, …
ASP.NET Core
.NET Core

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Summary
.NET Core is an implementation of .NET Standard
Runs cross-platform on Linux, macOS and Windows
Can be installed side-by-side
Cloud-ready
ASP.NET Core
.NET Core

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Cross-Platform Web Application & Web APIs
ASP.NET Core
ASP.NET Core

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Overview
Unifies MVC and Web APIs
Built-in dependency injection
Cloud-ready configuration system
HTTP Request Pipeline
Hostable in IIS or as Self Host
Everything’s a NuGet Package
Leads to having a lot packages installed (“Hello node_modules J”)
Built on .NET Core
Open Source, https://github.com/aspnet/Home
“Can I port my application to .NET Core?” https://icanhasdot.net/
ASP.NET Core
ASP.NET Core

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Compared to ASP.NET
ASP.NET Core
Runs on Linux, macOS, Windows
C#, F#
MVC & Web API
SignalR is in development
New platform, new toolings
Multiple versions per machine
MSDN: “Ultra Performance”
ASP.NET
Runs on Windows
C#, F#, VB.NET
MVC, Web API, WebForms, WebPages, SignalR
Mature platform
One version per machine
MSDN: “High Performance”
ASP.NET Core
ASP.NET Core

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Hosting
Kestrel: ASP.NET Core’s Web Server
IISIntegration to host in IIS
Mandatory for Azure
Specifies a class used
for Startup configuration
ASP.NET Core
ASP.NET Core
public class Program
{
public static void Main(string[] args)
{
var host = new WebHostBuilder()
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup()
.Build();
host.Run();
}
}

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Startup
ConfigureServices: Used for configuring the built-in dependency injection
Configure: Used for configuring the HTTP pipeline via IApplicationBuilder
ASP.NET Core
ASP.NET Core
public class Startup
{
public void ConfigureServices(IServiceCollection services) { }
public void Configure(IApplicationBuilder app,
IHostingEnvironment env, ILoggerFactory loggerFactory) { }
}

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Dependency Injection
Constructor injection should be preferred over direct DI container access
Overriding the container is possible, e.g. to use AutoFac instead
Throws an error when a dependency could not be resolved (e.g. wrong container configuration)
ASP.NET Core
ASP.NET Core

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Dependency Injection
Supports three lifetimes
Transient: Creates an instance each it is requested
Scoped: Creates an instance once per request
Singleton: Creates an instance once per application
ASP.NET Core
ASP.NET Core
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddScoped();
services.AddSingleton();
}

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Pipeline
Customizable HTTP pipeline
Every request will run through
Order in code defines the order of the pipeline
Nesting of pipelines is possible
IApplicationBuilder is used to define the pipeline
ASP.NET Core
ASP.NET Core
https://docs.microsoft.com/en-us/aspnet/core/fundamentals/middleware
public void Configure(IApplicationBuilder app)
{
app.UseExceptionHandler("/Home/Error");
app.UseStaticFiles();
app.UseMvcWithDefaultRoute();
}

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Multiple Environments
Support multiple environments like Development, Staging or Production out-of-box
Can be set via environment variable ASPNETCORE_ENVIRONMENT
Convention based application startup
Startup, StartupDevelopment, Startup{Environment}
Careful, using webhostBuilder.UseStartup() overrides this behavior
Configure, ConfigureDevelopment, Configure{Environment}
ConfigureServices, ConfigureDevelopmentServices, Configure{Environment}Services
ASP.NET Core
ASP.NET Core

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Multiple Environments
IHostingEnvironment for checking environment at runtime
Checking within a Razor View
ASP.NET Core
ASP.NET Core
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment() || env.IsProduction() || env.IsStaging() || env.IsEnvironment(”MyEnv"))
{ }
}

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Configuration System
ConfigurationBuilder is used to define configuration sources
Order is used for configuration overriding, later defined sources override previous defined
Optional sources and sources depending on the environment are possible
ASP.NET Core
ASP.NET Core
public Startup(IHostingEnvironment env)
{
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
.AddEnvironmentVariables();
Configuration = builder.Build();
}

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Authentication
Middleware within the pipeline
“Plug & Play” solutions for authentication
ASP.NET Identity
IdentityServer 4, open source project
Different authentication schemes
Cookies
Bearer
Basic
External providers
Custom
ASP.NET Core
ASP.NET Core

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Controllers
Two base classes for controllers
ControllerBase: Preferred for Web APIs, offers everything except Views
Controller: Preferred for MVC, inherits from ControllerBase and adds View capabilities
Offer various methods for returning a result
Ok() / NotFound() / StatusCodeResult()
FileResult() / FileContentResult() / FileStreamResult()
Offers access to authenticated user via User property
Can be asynchronous using async/await pattern
If enabled, automatic Content Negotiation
ASP.NET Core
ASP.NET Core

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Views
Represent (a piece of) HTML to be rendered in the browser
Uses Razor View Engine
Supports strongly typed Views with a ViewModel
Can make use of ViewBag, ViewData and Model to transfer data from and to controllers
General layout can be applied
ASP.NET Core
ASP.NET Core

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Routing
Routing: Mapping URLs to actions (methods within a controller)
Routing via definition in pipeline
Routing via attributes
ASP.NET Core
ASP.NET Core
{
app.UseMvc(routes => routes.MapRoute("api", "{controller}/{action}"));
}
[Route("customers")]
public class CustomerApiController : ControllerBase
{
[HttpGet("{id:int}")]
public IActionResult Get(int id) { }
}

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Routing
Routing via custom routing handler
Support for all important HTTP verbs like GET, POST, PUT, DELETE
Routing in Views via Tag Helpers
Controller can also be specified
Tag Helper asp-route-{parameter} accepts any custom parameter
ASP.NET Core
ASP.NET Core
Delete
Delete

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Error Handling
Provides a developer exception page with detailed information about errors
Supports error page per status code or custom error pages
Supports custom error filter per action, controller or globally
ASP.NET Core
ASP.NET Core
{
// Use in development only
app.UseDeveloperExceptionPage();
// Simple status code error pages
app.UseStatusCodePages();
// Custom error handler
app.UseExceptionHandler("/error");
}

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Swagger Help Pages
NuGet: Swashbuckle.AspNetCore
Swagger: Generates a swagger.json containing all information about your Web APIs
Swagger UI: Provides a basic UI to view the swagger.json
ASP.NET Core
ASP.NET Core
{
services.AddSwaggerGen(options =>
{
options.SwaggerDoc("v1", new Info() { Title = "Awesome Customer API", Version = "1.0" });
});
}
{
app.UseSwagger();
app.UseSwaggerUI(options => { options.SwaggerEndpoint("v1/swagger.json", "API v1"); });
}

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Swagger Help Pages
ASP.NET Core
ASP.NET Core

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Summary
Unifies MVC and Web APIs
Cloud-ready
HTTP Pipeline & Configuration System
Several hosting options
Help Pages via Swagger
ASP.NET Core
ASP.NET Core

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Lightweight & cross-platform data access
ASP.NET Core

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Overview
Open source implementation: https://github.com/aspnet/EntityFramework
Lightweight & cross-platform version of .NET’s full-fledged EntityFramework
Support different database providers
MS SQL
SQLite
Postgres
InMemory
Offers Commandline Tools
Code First, Database First
Migrations
ASP.NET Core

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Compared to EntityFramework 6
EntityFramework Core does not offer the following features, but they are in development
Complex value types (without an ID)
Spatial data (geography, geometry)
Graphical visualization of the model (Model First)
Complex LINQ-Queries
Many-to-Many without a joining entity
Lazy Loading
Stored Procedures
Data Seeding
Full list available at https://docs.microsoft.com/en-us/ef/efcore-and-ef6/features
ASP.NET Core

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NuGet Package & CLI
Core Package: Microsoft.EntityFrameworkCore
Database Provider Packages
MS SQL: Microsoft.EntityFrameworkCore.SqlServer
Postgres: Npgsql.EntityFrameworkCore.PostgreSQL
SQLite: Microsoft.EntityFrameworkCore.SQLite
CLI Tools
Powershell: Microsoft.EntityFrameworkCore.Tools
cmd/bash: Microsoft.EntityFrameworkCore.Tools.DotNet
Careful: cmd/bash is not installable via NuGet, only by editing .csproj directly
ASP.NET Core

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Model
Working with EntityFramework Core is based on a model
A model is a simple class with specific attributes
ASP.NET Core
public class CustomerEntity
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
[Required]
public string FirstName { get; set; }
public string LastName { get; set; }
public int Age { get; set; }
}

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Database Context
A database context (DbContext) represents a session to the database
Has one or multiple DbSet to query the database
Allows executing raw SQL queries
ASP.NET Core
public class SampleApplicationDbContext : DbContext
{
public SampleApplicationDbContext(DbContextOptions options)
: base(options)
{
// Overriding constructor is necessary to make use of DbContextOptions
}
public DbSet Customers { get; set; }
}

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Database Context
DbContext can be added to the dependency injection
Services can request a DbContext via constructor injection
ASP.NET Core
{
services.AddDbContext(options =>
{
options.UseSqlServer(Configuration.GetConnectionString("SampleApplication"));
}
);
}
public class CustomerService
{
public CustomerService(SampleApplicationDbContext dbContext)
{ }
}

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Fluent API
Instead of using attributes to define a model, the Fluent API can be used
Fluent API has a richer API than the attributes for more complex scenarios
ASP.NET Core
public class SampleApplicationDbContext : DbContext
{
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity()
.HasKey(e => e.Id);
modelBuilder.Entity()
.Property(e => e.FirstName)
.IsRequired();
}
}

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Querying
LINQ for database querying
Simple selects
Ordering
Grouping
Limiting
Can load related data
Eager Loading
Explicitly
Lazy Loading is in development
ASP.NET Core
public class CustomerService
{
private readonly SampleApplicationDbContext _dbContext;
public CustomerService(SampleApplicationDbContext dbContext)
{
_dbContext = dbContext;
}
public ICollection List()
{
return _dbContext.Customers
.OrderBy(c => c.Id)
.ToList();
}
}

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Saving
Tracks changes on entities per default
Writes back changes to the database when the DbContext is saved
ASP.NET Core
public void Update()
{
var entity = _dbContext.Customers.First();
entity.FirstName = "Max";
_dbContext.SaveChanges();
}

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Saving
Related data is also saved on change tracked entities
Use AsNoTracking() when querying to not track changes, e.g. for read-only scenarios
ASP.NET Core
public ICollection List()
{
return _dbContext.Customers
.AsNoTracking() .ToList();
}

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Transactions
SaveChanges() calls done as a transaction by default
Custom transaction can be create by using DbContext.Database.BeginTransaction()
ASP.NET Core
using (var transaction = _dbContext.Database.BeginTransaction())
{
try
{
_dbContext.Customers.Add(new CustomerEntity { FirstName = "Max" });
_dbContext.Customers.Add(new CustomerEntity { FirstName = "Erika" });
transaction.Commit();
}
catch (Exception e)
{
// TODO: Handle exception
}
}

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Migrations
Needs the PowerShell or cmd/bash tools installed
Add Migrations via
PowerShell: Add-Migration MigrationName
cmd/bash: dotnet ef migrations add MigrationName
Custom database initializer is needed to actually apply the migrations on startup
ASP.NET Core
public class DatabaseInitializer
{
public void Migrate()
{
_dbContext.Database.Migrate();
}
}

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Summary
Cross-platform version of .NET’s EntityFramework
Not all features are supported yet
Offers PowerShell and cmd/bash toolings
Supports transactions & migrations
Support multiple database providers and an InMemory database for testing
ASP.NET Core

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Summary
.NET Standard makes it easier to create multi-targeting code (replacing PCLs)
.NET Standard 2.0 can target existing .NET code to reuse your existing business logic
ASP.NET Core provides a cross-platform possibility for MVC & Web APIs
ASP.NET Core is cloud-ready and offers a customizable HTTP pipeline
EntityFramework Core provides cross-platform and cross-database capabilities
ASP.NET Core
.NET Core & ASP.NET Core & EntityFramework Core

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.NET Standard MSDN
https://docs.microsoft.com/en-us/dotnet/articles/standard/library
Introducing .NET Standard
.NET Core MSDN
https://docs.microsoft.com/en-us/dotnet/articles/core/
ASP.NET Core MVC MSDN
https://docs.microsoft.com/en-us/aspnet/core/mvc/overview
ASP.NET Core Web API MSDN
https://docs.microsoft.com/en-us/aspnet/core/mvc/web-api/
EntityFramework Core MSDN
https://docs.microsoft.com/en-us/ef/
ASP.NET Core
Resources

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Modern & Pragmatisch
Christian Weyer
May the 4th 2017 @ 2 PM
Mythos Microservices & wie diese in der .NET-Welt funktionieren
ASP.NET Core
Microservices-Architekturen .NET/.NET Core

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Thank you! Questions?
Repository
Manuel Rauber
@manuelrauber
Software Architect
https://github.com/thinktecture/dotnet-summit-2017-asp-dot-net-core

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Cross-Plattform-Serveranwendungen mit ASP.NET Core

Cross-Plattform-Serveranwendungen mit ASP.NET Core

Manuel Rauber

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