I present to you a template to create a modular web application based on ASP.NET Core. It uses the basic features of MVC framework for the organization of a modular architecture. Each module is a dll file, which includes views and static files. Each module has a standard structure MVC application:

ModuleName/
├── Controllers/
│   ├── HomeController.cs
│   └── ...
├── Models/
│   ├── Model.cs
│   └── ...    
├── Views/
│   ├── Home
│   │   ├── Index.cshtml
|   |   └── ...
|   └── ...
├── wwwroot/
│   ├── css
|   |   └── ...
│   ├── js
|   |   └── ...
│   ├── img
|   |   └── ...
|   └── ...
└── ModuleInfo.cs

The following steps describe the actions in the Windows environment using Visual Studio

• Clone repository
• Open solution ModularWebApp.sln
• Compile project Host
• Compile project Module.Account
• Create a folder Modules inside 'output' folder of Host compilation (example, Host\bin\Debug\netcoreapp1.1)
• Copy the contents of the project compilation Module.Account to the folder Modules
• Run project Host

By default, the current folder of Host.dll file is taken and it is sought inside its Modules folder. But you can also specify a full path to find modules by using ModulesPath setting in appsettings.json file.

P.S. For *nix systems actions algorithm similar, only with the use of util dotnet

Main feature of the project Core is the presence of a class CoreMvcBuilderExtensions, which loads the assembly of each module of the specified folder, and keeps a list of the type IModuleBase interfaces. Startup class of the project Host has the following changes:

• Method ConfigureServices:

...

public void ConfigureServices(IServiceCollection services)
{
    // Load assemblies by AddMvcModules
    services.AddMvc().AddMvcModules(services, Configuration);
}

...

• Method Configure:

...

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    loggerFactory.AddConsole(Configuration.GetSection("Logging"));
    loggerFactory.AddDebug();

    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
        app.UseBrowserLink();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
    }

    app.UseStaticFiles();

    // Add modules assemblies for static files serving
    app.UseMvcModulesStaticFiles(env, loggerFactory, Configuration);

    app.UseMvc(routes =>
    {
        // Add route for area handling
        routes.UseMvcModulesRoute();
        routes.MapRoute(name: "default", template: "{controller=Home}/{action=Index}/{id?}");
    });
}

...

And special attention should be paid to the file _Layout.cshtml, which shows how you can generate a navigation bar based on modules.

...

@foreach (var panel in CoreMvcBuilderExtensions.ModulesList.Where(x => x.Features.Get<ISideBarPanelFeature>() != null).Select(x => x.Features.Get<ISideBarPanelFeature>()))
{
    @if (panel.SubMenu?.Count > 0)
    {
        <li id="@panel.Id" class="dropdown">
            <a class="dropdown-toggle" data-toggle="dropdown" href="#@panel.Id" role="button" aria-haspopup="true" aria-expanded="false">
                @panel.Title
                <span class="caret"></span>
            </a>
            <ul class="dropdown-menu">
                @foreach (var sub in panel.SubMenu)
                {
                    <li id="@sub.Id-sub"><a asp-action="@sub.Action" asp-controller="@sub.Controller" asp-area="@sub.Area">@sub.Title</a></li>
                }
            </ul>
        </li>
    }
    else
    {
        <li>
            <a class="nav-link" href="@panel.Url"><i class="fa @panel.FAIcon"></i>@panel.Title</a>
        </li>
    }
}

...

When you create a new module, it is necessary to observe the following rules:

• The module should be dependent on the project Core
• The module must implement the interface IModuleBase
• Each controller must have the attribute Area with the same value
• To specify the name of the controller to display the name on the navigation bar, use the Features property
• The attribute value Area and the last word in the name of the project should be the same. For example, if your module is called Product, then each controller must have Area with a value of Product. If your project is called My.Modular.App.Module.Product, the Area should be set to Product
• The module must have a constructor that takes a single parameter of type Assembly
• The file *.csproj must have the following entry: <ItemGroup><EmbeddedResource Include="Views\**;wwwroot\**" Exclude="bin\**;obj\**;**\*.xproj;packages\**;@(EmbeddedResource)" /></ItemGroup>

This TagHelper may help you in specifying the url address to the static module resources. For example, if you just specify ~/js/test.js in an attribute src of element script, you will get the address of </ApplicationName>/js/test.js. But if you use TagHelper, the address will be the following </ApplicationName>/ControllerAreaName/js/test.js. Example:

<link rel="stylesheet" cth-src="~/css/site.css" /> -> <link rel="stylesheet" href="/myapp/module/css/site.css" />
<script type="text/javascript" cth-src="~/js/test.js"></script> -> <script type="text/javascript" src="/myapp/module/js/test.js"></script>