Best practice: Dependency injection

This section explains how to follow best practices when using the Digital Twin SDKs.

Overview

The Digital Twin SDKs have APIs that follow the dependency injection pattern, which means each service constructor requires you to provide dependencies based on your preferences.

This pattern is useful for advanced use cases because it simplifies the customization of specific components and uses the default implementation for the remaining components. You can use the default implementations for simple usage, but you must link the services together.

The samples and documentation for Identity use a best practice pattern and this section explains how that best practice pattern works.

Implement the PlatformServices pattern

1. Create a PlatformServices static class with InitializeAsync and Shutdown methods. This class initializes and disposes of all Digital Twin services, while also publicly exposing the services as singletons.

       public static class PlatformServices
       {
           public static async Task InitializeAsync()
           {
   
           }
   
           public static void Shutdown()
           {
   
           }
       }
   

2. Create a PlatformServicesInitialization MonoBehaviour that calls the PlatformService's InitializeAsync in Awake. The DefaultExecutionOrder attribute ensures this script is called before any other script in your project and DontDestroyOnLoad ensures the GameObject isn't destroyed when loading another scene.

       [DefaultExecutionOrder(int.MinValue)]
       public class PlatformServicesInitialization : MonoBehaviour
       {
           async Task Awake()
           {
               DontDestroyOnLoad(gameObject);
               await PlatformServices.InitializeAsync();
           }
       }
   

3. Create a PlatformServicesShutdown MonoBehavior that calls the PlatformService's Shutdown in OnDestroy. The DefaultExecutionOrder attribute ensures this script is called after any other script in your project.

       [DefaultExecutionOrder(int.MaxValue)]
       public class PlatformServicesShutdown : MonoBehaviour
       {
           void OnDestroy()
           {
               PlatformServices.Shutdown();
           }
       }
   

4. Create a PlatformServices GameObject and attach the PlatformServicesInitialization and PlatformServicesShutdown scripts. Make sure this GameObject instantiates only once in your project, which is when the application launches.

5. Populate the PlatformServices class with the services you require.