Dependency Injection Service Lifetime in C# .NET Core

Dependency Injection Service Lifetime in C# .NET Core

Dependency Injection (DI) is a design pattern commonly used in C# .NET Core applications to manage the dependencies between different components. When registering services in the DI container, you can specify the service lifetime, which determines how long a service instance will be maintained.

There are three main service lifetimes available in C# .NET Core: Transient, Scoped, and Singleton. Each has its own purpose and usage scenarios. Let's explore each of them in detail:

1. Transient Lifetime: Transient lifetime services are created each time they are requested from the DI container. A new instance is provided for every request, ensuring that each consumer receives a separate instance. Transient services are suitable for lightweight, stateless dependencies.

csharp
services.AddTransient<IService, TransientService>();

In the above example, TransientService will be created every time it is injected into a consuming class. This is ideal for services that don't store any mutable state and are safe to use in a multi-threaded environment.

2. Scoped Lifetime: Scoped lifetime services are created once per client request within the same scope. A new instance is provided for each different scope, but the same instance is reused within a single scope. Scoped services are commonly used in web applications.

csharp
services.AddScoped<IService, ScopedService>();

In the above code, a new instance of ScopedService is created for every HTTP request. If the same service is requested within the same request, the DI container returns the previously created instance.

3. Singleton Lifetime: Singleton lifetime services are created once and shared across all clients. A single instance is created and reused throughout the application's lifetime. Singleton services are suitable for stateful components that need to maintain their state between different requests.

csharp
services.AddSingleton<IService, SingletonService>();

The above example registers SingletonService as a singleton. Any subsequent requests for the IService interface will receive the same instance. This is useful for services that store shared state or perform expensive initialization.

It's important to note that while singletons can be efficient and convenient, you should be cautious when using them with mutable state to avoid concurrency issues.

In conclusion, choosing the appropriate service lifetime in C# .NET Core depends on the specific requirements of your application. By understanding the differences between transient, scoped, and singleton lifetimes, you can effectively manage the dependencies and ensure the correct behavior of your components.