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Building Cross platform Applications with .NET Core

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Pritesh Patel edited this page Jul 26, 2019 · 13 revisions

https://app.pluralsight.com/library/courses/dotnet-core-building-cross-platform-applications/

Course Overview

  • Build console apps, services and web apps

Building Console Apps

Overview

  • Build/run on a variety of platforms
  • Switch from project.json (.NET Core RC versions) to MSBuild (.NET Core 1.0 onwards) tooling
  • .NET Core is open-source

The State of .NET Core

  • Runtime vs SDK/Tools
  • SDK refers to just the dotnet CLI
  • .NET Core 1.2/2.0 - netstandard 2.0 (runtime)
  • project.json -> MSBuild VS2017 (SDK)
  • Note: Additions to .NET Core 2.0 e.g. .NET Standard 2.0 support, ASP.NET Core Razor pages, MSBuild support

Choosing Development Tools

  • tools available for cross-platform .NET Core application dev
  • single platform: VS Studio 2017 and later, VS Studio for Mac
  • cross platform: VS Code, Jet Brains Rider, dotnet cli
  • no issue in developers using different platforms to contribute to a project, MSBuild tooling is consistent cross-platform

How To Get The Latest SDK Builds

  • See Microsoft .NET Core website

Creating a Console App with dotnet new

  • creating an app that checks links are working on a webpage
  • dotnet new -h and dotnet new console

The New .NET Core MSBuild Project System

  • cf. project.json (old .NET Core config file) with new MSBuild .csproj file
  • project.json no longer exists but global.json can still be used to override config (e.g. specify .net core version to use)
  • dotnet --version displays the version of .NET Core project is using

The Goal Is A Clean MSBuild Project File

  • The cleaner .csproj file aims to match the simplicity of the previous project.json file
  • This is achieved by development of MSBuild which can handle the simpler, cleaner .csproj files

Build and Run the Console App on a Mac

  • dotnet restore to restore package dependencies
  • dotnet build (optional) to build app
  • dotnet run builds and runs app
  • tree to view current directory hierarchy
  • obj\project.assets.json replaces previous project.lock.json file

Build and Run on Windows

  • use the same commands as above for Mac (predictably!)

Build and Run On Linux via Docker and Custom Docker Images

  • docker run -it microsoft/dotnet:latest runs a docker container with image containing .NET Core toolchain
  • docker run -it microsoft/dotnet:1.0.3-sdk-msbuild run specified .NET Core version
  • docker run -it -v $(pwd):/console microsoft/dotnet:1.0.3-sdk-msbuild mount host machine's volume within the docker container (e.g. to access source code)
  • can download and customise an existing docker file as required
  • docker build -t dotnet-sdk-preview4 -f Dockerfile.preview4 . builds a docker image from a docker file in the current dir
  • docker images | grep dotnet list available docker images
  • docker run --rm -it -v $(pwd)/CheckLinksConsole:/console dotnet-sdk/preview4 - runs container with the specified image, removing the container after execution completes, map the volume (as previous)
  • run the same commands to restore, build and run console app
  • Windows containers see Nano Server and Server Core which can be used with a Windows container

You Can Work With Both An IDE and the dotnet CLI

  • dotnet CLI was originally built to work with project.json, but since being replaced with the new .csproj file it mostly now just 'shells' out to MSBuild
  • SDKs used by VS.NET/VS Code work directly with MSBuild, dotnet CLI can be used by other editors/IDEs or can be used directly
  • The SDK provides core functionality needed by .NET core projects - MSBuild tasks and project templates - used by VisualStudio and CLI

Creating a Solution File with Visual Studio

  • You can open the project created above in VS.NET and save the solution file which can then be opened by e.g. VS.NET for Mac

You Can Create Projects with an IDE Too

  • You can use the editor to create .NET Core projects, although there appear to be more options available when using the CLI (which has been been developed more in the open with it being open source)

Finding an API to Make a Web Request

Using an API Bundled with .NET Core to Make Web Requests

  • Can check Dependencies in VS.NET to ensure required package is already included or add it if required
  • VS.NET will use SDK to build and then run app

Is This NuGet Package Compatible with .NET Core?

  • Search for NuGet packages on https://www.nuget.org
  • Best Case - package supports .NET Standard
  • Can also use PackageTargetFallback to use .NET Framework packages if it is known to work with .NET Core (test!)
  • Use a fork that supports .NET Standard (or .NET Core)
  • Create own fork if one doesn't exist
  • .NET Standard 2.0 - compatible with .NET Framework packages! (provides support for full BCL) - see https://devblogs.microsoft.com/dotnet/introducing-net-standard/. .NET Standard 2 provides a compatiblity shim for .NET Framework binaries
  • use dotnet-apiport (command line tool) to scan a DLL to analyse whether it is compatible

Extracting Links With HtmlAgilityPack

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