In this lesson, you will learn how to structure large-scale Blazor and ASP.NET Core applications into independent projects based on business domains rather than just technical layers.
Moving Beyond the "All-in-One" Web Project
In smaller applications, it is common to put all your pages, services, and models into a single web project. As your application grows, this "monolith" becomes difficult to maintain. When every component and service lives in the same project, dependency management becomes a nightmare, and build times skyrocket.
To solve this, we shift to Domain-Driven Modularization. Instead of having folders for Services and Controllers, we create separate Class Library projects for each business domain, such as MyApp.Orders, MyApp.Inventory, and MyApp.Identity.
How to Structure Your Solution
By separating your code into domain-specific projects, you enforce strict boundaries. For example, the Inventory project should not know how the Orders project handles billing. You can expose only the necessary interfaces through a common Core or Shared project, keeping the internal logic of each domain hidden.
When working with Blazor, this approach allows you to group your Razor components alongside their logic:
// Inside MyCompany.Orders.csproj
// This project contains only the logic and UI specific to orders
public class OrderService : IOrderService { ... }
// You then reference these in your main Blazor WebAssembly project:
builder.Services.AddScoped<IOrderService, OrderService>();
The Benefits of Decoupling
Modularization transforms your architecture by enabling:
- Independent Deployment: You can potentially update or swap out a domain module without touching the rest of the application.
- Compile-time Enforcement: If a project does not have a reference to another, you physically cannot call its code. This prevents the "spaghetti code" effect where everything is tightly coupled to everything else.
- Parallel Development: Different team members can work on
InventoryandOrderssimultaneously in their own projects without constantly resolving file merge conflicts.
As you scale your application, stop thinking about where files go and start thinking about what business capability this project provides.
Key Takeaway: Modularizing by business domain replaces a bloated single-project structure with loosely coupled, maintainable libraries that enforce clean boundaries and simplify long-term scaling.