NBattleship Coding Contest

Learning by example

Rainer Stropek | @rstropek | time cockpit

Workshop Rules

  • Make it interactive
  • Make it practically relevant
    • Ask questions relevant to your projects
  • Follow along if you are an experienced C# dev

Use Case

  • Build a runtime for classical Battleship game
    • Practical relevance: Extensible runtime for business software
    • Example: ERP, machine configuration, CAD
  • Other developers contribute computer players through well-defined API
    • Practical relevance: Plugins developed by a distributed team of devs
  • Players must run in an isolated sandbox (e.g. process, container)
    • Practical relevance: Semi-trusted plugins, protection from crashes
  • Easy to use CLI for controlling processes
    • Well suited for Docker
  • Later: Web-based UI (HTTP, Websockets) for controlling the games
    • Practical relevance: Web UI for business software

Technical Requirements

  • Latest version of .NET
    • .NET 5 Preview
  • Make shipping and installing simple
    • Single executable for entire backend
  • Solid unit test coverage
  • Cross-platform
  • High performance for communicating with players
    • Avoid run-time reflection in custom code
    • Fast communication protocol to players​

Out of Scope

  • UI
    • CLI
    • ​HTTP-based web API
  • Complex tournament logic
    • ​For today, enough if two players can play against each other
  • Harden software against player crashes
    • Architecture has to make that possible in the future

Manager

Battle Host

Architecture

Manager

Battle Host

Player

Player

Architecture

Manager

Battle Host

Player

Player

Separate process
or container

Architecture

Manager

Battle Host

Player

Player

gRPC duplex streaming

Separate process
or container

Architecture

Manager

Battle Host

Player

Player

gRPC duplex streaming

Separate process
or container

UI

HTTP

Architecture

Manager

Battle Host

Player

Player

gRPC duplex streaming

Separate process
or container

UI

HTTP

SignalR

Architecture

Communication Protocol

Manager

Battle Host

Player

Request Shot

Shoot

Shot

Shot

Shot Result

Shot Result

Learning Goals

  • Work with .NET 5
    • Web APIs (HTTP, gRPC)
    • Class libraries
    • Unit tests
    • Generic host
  • Use new C# features
  • Interop between .NET Standard libs and .NET 5
  • Learn about Roslyn's C# Code Generator

Prerequisites to Follow Along

  • Latest Visual Studio 2019 Preview
    • 16.8.0 Preview 3.0
  • Latest .NET 5 Preview
    • .NET Runtime 5.0.0-rc.1.20451.14
    • ASP.NET Core Runtime 5.0.0-rc.1.20451.14
    • Part of SDK 5.0.100-rc.1
  • Clone GitHub Repo

Have Fun, Learn a Lot!