Plugin Architecture In Blazor – A How To Guide
Tags: csharp, dotnet, blazor, aspdotnet
Published: 2023-09-22 16:00:00

In modern software development, modularity is a key principle. It promotes the creation of software components that are independent and organized. This approach aids in efficient development, maintenance, and scalability and the plugin architecture aligns with this principle. This article will be a step-by-step guide to using Autofac to create an application with a [plugin architecture](https://www.devleader.ca/2023/09/07/plugin-architecture-design-pattern-a-beginners-guide-to-modularity/) in Blazor.

Within C# web development, frameworks like Blazor have highlighted the utility of plugins. Blazor’s component-based structure is conducive to the implementation of plugins, offering developers a method to expand applications without extensive modifications. So if that sounds exciting, let’s get into it!

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### Understanding Plugin Architecture

[A plugin architecture is a design pattern](https://www.devleader.ca/2023/09/07/plugin-architecture-design-pattern-a-beginners-guide-to-modularity/) that enables the addition of new functionalities to a system without changing its existing structure. It’s akin to adding modules to a base system; the primary system remains intact, but its functions are expanded.

There are several reasons to consider a plugin-based approach for web applications:

1. **Flexibility**: Plugins provide a way to introduce or alter features without modifying the core application. This adaptability ensures the application can meet new requirements without significant changes.
    
2. **Maintainability**: Plugins are distinct from the main application, allowing for independent updates or fixes. This separation means that alterations to one plugin don’t impact others or the central application.
    
3. **Scalability**: As the application’s needs grow, it can incorporate new plugins. This modular approach ensures manageability, even as the application becomes more complex.
    
4. **Collaboration**: Different [development teams or individuals can work on separate plugins at the same time](https://www.devleader.ca/2023/08/31/why-the-best-developers-are-obsessed-with-vertical-slices/), facilitating parallel development.
    

The following sections will detail how to implement this architecture in a Blazor application, using Autofac for dependency management.

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### Setting the Stage: Tools and Technologies

### Introduction to Blazor

[Blazor is a framework from Microsoft](https://learn.microsoft.com/en-us/aspnet/core/blazor/?view=aspnetcore-7.0) that allows developers to build interactive web applications using C# instead of JavaScript. It’s part of the .NET ecosystem and offers two hosting models:

1. **Blazor WebAssembly**: This model runs the client-side C# code directly in the browser using WebAssembly. It allows for the development of single-page applications (SPAs) with .NET.
    
2. **Blazor Server**: In this model, the C# code runs on the server, and the UI updates, event handling, and JavaScript calls are handled over a real-time SignalR connection.
    

Blazor’s component-based architecture makes it a suitable candidate for implementing a plugin system. Each component in Blazor is a self-contained unit of code, UI, and any associated logic, making it modular by design.

### Autofac in the Context of Blazor

[Autofac is a popular inversion of control (IoC) container for .NET](https://www.devleader.ca/2023/08/22/dependency-injection-how-to-start-with-autofac-the-easy-way/). It provides [dependency injection](https://www.devleader.ca/2023/08/22/dependency-injection-how-to-start-with-autofac-the-easy-way/) (DI) capabilities, which is a technique to achieve Inversion of Control between classes and their dependencies.

In the context of Blazor, Autofac can be used to manage the dependencies of Blazor components. [Dependency injection is crucial in modern web development for several reasons](https://www.devleader.ca/2023/07/31/plugin-architecture-in-asp-net-core-how-to-master-it/):

1. **Separation of Concerns**: DI promotes a separation between the creation of objects and the business logic that uses them. This separation makes the codebase cleaner and more maintainable.
    
2. **Testability**: By injecting dependencies, it becomes easier to replace real implementations with mock objects, facilitating unit testing.
    
3. **Flexibility**: DI allows developers to switch out implementations without changing the components that depend on them. This flexibility is especially beneficial in a plugin architecture where different plugins might have varying implementations for shared interfaces.
    

Next, let’s delve into how these can be combined to create a robust plugin architecture in Blazor with Autofac.

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### Designing a Plugin Architecture in Blazor

### Core Components for a Plugin Architecture in Blazor

When designing a plugin system for Blazor using Autofac, it’s essential to understand the [core components that make up this architecture](https://www.devleader.ca/2023/07/31/plugin-architecture-in-asp-net-core-how-to-master-it/). These components ensure modularity and extensibility, allowing developers to add or remove features with ease.

* **Host Application:** The host application is the primary Blazor application that serves as the foundation for the plugins. It provides the necessary infrastructure to load, manage, and interact with plugins. The host application should be designed with extensibility in mind, ensuring that it can accommodate new plugins without significant changes. This involves setting up the necessary routes, layouts, and dependency injection configurations to support the dynamic addition of plugins.
    
* **Plugin Interface:** The plugin interface is a crucial component in the plugin architecture. It defines a contract that all plugins must adhere to. This contract ensures a consistent way for the host application to communicate with and manage plugins. By defining methods, properties, or events in the interface, you set clear expectations for what a plugin should provide. For instance, the interface might specify methods for initializing the plugin, rendering its UI, or handling specific events. In the context of Autofac, the plugin interface also plays a vital role in [dependency injection](https://www.devleader.ca/2023/08/22/dependency-injection-how-to-start-with-autofac-the-easy-way/). By registering the interface with Autofac, you can ensure that the correct plugin implementations are provided wherever the interface is required.
    
* **Plugins:** Plugins are individual modules that extend the functionality of the host Blazor application. Each plugin is a self-contained unit, encapsulating specific features or functionalities. When developing plugins, it’s essential to implement the previously defined plugin interface. This ensures that the host application can seamlessly integrate the plugin. In a Blazor application, a plugin might consist of multiple components, services, or even additional dependencies. Using Autofac, these dependencies can be registered and resolved within the plugin, ensuring that each plugin can operate independently while still integrating smoothly with the host application.
    

---

### Integrating Autofac into a Blazor Project

{% embed https://youtu.be/fTyubohxBGU %} 

To start using Autofac in a Blazor application, you’ll first need to add the necessary NuGet packages. For a Blazor WebAssembly project, you’d typically require `Autofac.Extensions.DependencyInjection` and `Autofac`.

Once the packages are added, you can configure Autofac in the `Program.cs` file of your Blazor application. Instead of using the default DI container provided by Blazor, you’ll replace it with Autofac.

### Configure With WebAssemblyHostBuilder

If you’re using WebAssemblyHostBuilder, here’s a basic setup:

```csharp
public static async Task Main(string[] args)
{
    var builder = WebAssemblyHostBuilder.CreateDefault(args);
    builder.RootComponents.Add<App>("#app");

    // Set up Autofac
    var containerBuilder = new ContainerBuilder();
    containerBuilder.RegisterModule(new YourAutofacModule());
    // ... any other Autofac registrations ...
    builder.Services.AddAutofac();

    var host = builder.Build();
    host.Services.UseAutofacContainer(containerBuilder.Build());

    await host.RunAsync();
}
```

### Configure With WebApplicationBuilder

If you’re using a WebApplicationBuilder, things need to work a little bit differently! Here’s a basic setup:

```csharp
var builder = WebApplication.CreateBuilder(args);
var containerBuilder = new ContainerBuilder();

// Add services to the container.
builder.Services.AddAutofac();
builder.Services.AddRazorPages();
builder.Services.AddServerSideBlazor();

builder.Host.UseServiceProviderFactory(new AutofacServiceProviderFactory());
builder.Host.ConfigureContainer<ContainerBuilder>(containerBuilder =>
{
    containerBuilder.RegisterModule(new YourAutofacModule());
    // ... any other Autofac registrations ...
});

var app = builder.Build();
```

---

### Configuring Dependency Injection with Autofac

Want to see how to set up your DI with Autofac and [walk through a Blazor plugin example in more depth](https://www.devleader.ca/2023/09/14/plugin-architecture-in-blazor-a-how-to-guide/)? Check out [the full article on my site](https://www.devleader.ca/2023/09/14/plugin-architecture-in-blazor-a-how-to-guide/) for source code and an example of how to get started!