App Lifecycle

This document outlines the core concepts, scenes, and services involved in the app lifecycle, as well as the order of events during startup and session management.

Core Components

Standard Scenes

Lobby Scene

• Entry point for clients
• Allows users to view active sessions, create new ones, and select content

Session Scene

• Primary scene for training simulations
• Contains elements like player rig, UI, and runtime services
• Servers start directly in this scene and await client connections

Key Services

AppLifecycleService

Handles transitions between Lobby and Session scenes, manages ECS worlds, and provides methods for starting different types of sessions.

LocalPlayerInfoService

Carries player information such as selected content scene between Lobby and Session scenes.

Lifecycle Flow

Application Startup

1. Startup.cs configures the app and registers services
2. NetCodeBootstrap.cs runs:
   • For server builds: Starts a server-hosted session using AppLifecycleService
   • For client builds or editor:
     • Creates offline client+server NetCode worlds
     • Allows AppLifecycleService to be triggered for starting or joining sessions

Scene Transitions

Lobby to Session

• Triggered when a session is selected in the Lobby
• AppLifecycleService manages the transition
• Selected content scene info is carried over via LocalPlayerInfoService

Session to Lobby

• Allows clients to return to Lobby to join or create new sessions

Content Scene Loading

• Content scenes are loaded additively during a session
• Selected in Lobby and carried over to Session using LocalPlayerInfoService
• For details, see the Loading Content Scenes page

Usage Example

Here's a basic example of how to use the AppLifecycleService:

using Kanda.Foundation.DependencyInjection;
using Unity.Entities.Content;
using UnityEngine;
using Kanda.Foundation.Lifecycle;
using Kanda.Foundation.Lifecycle.Services;
 
public class AppLifecycleExample : MonoBehaviour
{
    [SerializeField] private string _entitySceneName;
    [SerializeField] private WeakObjectSceneReference _entitySceneReference;
 
    private IAppLifecycleService _appLifecycleService;
    private ILocalPlayerInfoService _localPlayerInfoService;
 
    private void Awake()
    {
        _appLifecycleService = AppServiceLocator.Get<IAppLifecycleService>();
        _localPlayerInfoService = AppServiceLocator.Get<ILocalPlayerInfoService>();
        
        _localPlayerInfoService.SetSelectedContentScene(new ContentSceneMetadata
        {
            Name = _entitySceneName,
            Guid = _entitySceneReference.Id.GlobalId.AssetGUID
        });
    }
 
    public async void GoToLobby()
    {
        var result = await _appLifecycleService.Lobby.Go();
        Debug.Log(result.Succeeded ? "Went to lobby successfully" : "Failed to go to lobby: " + result.Message);
    }
 
    public async void StartOfflineSession()
    {
        var result = await _appLifecycleService.Offline.Host();
        Debug.Log(result.Succeeded ? "Started offline session successfully" : "Failed to start offline session: " + result.Message);
    }
 
    // Additional methods for other session types...
}

Session Strategies

The AppLifecycleService uses different strategies for managing various session types. These strategies can be overridden to customize behavior for specific needs.

Strategy Types

• ILobbyStrategy: Handles transitioning to the lobby.
• IOfflineSessionStrategy: Manages offline (single-player) sessions.
• ILanSessionStrategy: Handles client-hosted sessions using local network.
• IRelaySessionStrategy: Handles client-hosted session using a relay.
• IServerSessionHostingStrategy: Manages dedicated server-hosted sessions.
• IServerSessionJoiningStrategy: Handles joining server-hosted sessions.

For more details on these strategies, see Session Hosting Modes.