Managing Multi-Project Solutions

Multi-project solutions allow you to split large applications into modular parts like services, libraries, and UI layers. Visual Studio makes it easy to organize, reference, and manage these projects within a single solution.

What is a Solution?

A solution in Visual Studio is a container for one or more related projects. Each project can represent a different component of your application (UI, API, data layer, etc.).

File extension: .sln
Supports cross-platform and mixed language projects
Useful for microservices or layered architecture

Adding Multiple Projects

Right-click on the solution → Add → New Project
Select a project type (e.g., Class Library, Console App, ASP.NET API)
Repeat to add more as needed

Referencing Projects

You can share code between projects by adding references:

Right-click on project → Add → Project Reference
Select the other project to link
Use using directive in code to access its classes

// In Project A (Library)
public class MathUtil
{
    public static int Multiply(int x, int y) => x * y;
}

// In Project B (Console)
using ProjectA;

Console.WriteLine(MathUtil.Multiply(3, 4));

Managing Build Order and Dependencies

Visual Studio automatically builds projects in the correct order based on references. You can check and manage build order:

Right-click on solution → Project Dependencies
Ensure foundational libraries are built before dependent projects

Solution Explorer Tips

Right-click → Set as Startup Project to change the launch project
Group projects using folders for better organization
Use filters to quickly find files, classes, or members

Example: 3-Tier Architecture

Project.Core – Shared business logic
Project.Data – Data access (e.g., EF Core)
Project.Web – ASP.NET Core frontend or API

Each layer depends only on the lower ones, promoting separation of concerns.

Multi-project solutions improve code organization, modularity, and reusability. Next, we’ll see how to extend Visual Studio with plugins and manage dependencies using NuGet Package Manager.

← Previous: Debugging Tools Next: Using Extensions and NuGet Package Manager →