Merge pull request #12610 from abpframework/EngincanV/appnolayers-documentation

Document the single layer application startup template (`app-nolayers`)

docs/en/Startup-Templates/Application-Single-Layer.md

@@ -0,0 +1,106 @@
+# Application (Single Layer) Startup Template
+
+## Introduction
+
+This template provides a single-layered application for a quick start with ABP Framework. 
+
+This document explains the **solution structure** and project in detail.
+
+### What is the Difference Between the Application Startup Templates?
+
+ABP's [Application Startup Template](Application.md) provides a well-organized and layered solution to create maintainable business applications based on the [Domain Driven Design](../Domain-Driven-Design.md) (DDD) practices. However, some developers find this template a little bit complex (or unnecessary) for simple and short-time applications.
+
+At this point, a single-layer application template has been created for such applications. This template has the same functionality, features and modules on runtime with the [Application Startup Template](Application.md) but the development model is minimal and everything is in a single project (`.csproj`).
+
+## How to Start with It?
+
+You can use the [ABP CLI](../CLI.md) to create a new project using this startup template. Alternatively, you can directly create & download this startup template from the [Get Started](https://abp.io/get-started) page. How to download via CLI is explained in this section.
+
+Firstly, install the ABP CLI if you haven't installed it before:
+
+```bash
+dotnet tool install -g Volo.Abp.Cli
+```
+
+Then, use the `abp new` command in an empty folder to create a new solution:
+
+```bash
+abp new Acme.BookStore -t app-nolayers
+```
+
+* `Acme.BookStore` is the solution name, like *YourCompany.YourProduct*. You can use single-level, two-level or three-level naming.
+* In this example, the `-t` option (or `--template` option) specifies the template name.
+ 
+### Specify the UI Framework
+
+This template provides multiple UI frameworks:
+
+* `mvc`: ASP.NET Core MVC UI with Razor Pages (default)
+* `blazor-server`: Blazor Server UI
+* `angular`: Angular UI
+* `none`: Without UI
+
+> Currently, this template doesn't have Blazor WASM UI, because it requires 3 projects at least (server-side, UI and shared library between these two projects). 
+
+Use the `-u` or `--ui` option to specify the UI framework while creating the solution:
+
+```bash
+abp new Acme.BookStore -t app-nolayers -u angular
+```
+
+* This example specifies the UI type (`-u` option) as `angular`, you can also specify `mvc` or `blazor-server` for UI type.
+
+### Specify the Database Provider
+
+This template supports the following database providers:
+
+- `ef`: Entity Framework Core (default)
+- `mongodb`: MongoDB
+
+Use the `-d` (or `--database-provider`) option to specify the database provider while creating the solution:
+
+```bash
+abp new Acme.BookStore -t app-nolayers -d mongodb
+```
+
+## Solution Structure
+
+If you don't specify any additional options while creating an `app-nolayers` template, you will have a solution as shown below:
+
+![](../images/bookstore-single-layer-solution-structure.png)
+
+It's a single-layer template rather than a layered-architecture solution (like the `Application Startup Template`). It's helpful to create a running application quickly without considering the layered architecture.
+
+### Folder Structure
+
+Since this template provides a single-layer solution, we've separated concerns into folders instead of layers and you can see the pre-defined folders as shown below:
+
+![](../images/single-layer-folder-structure.png)
+
+* You can define your `entities`, `application services`, `DTOs`, etc. in this single project (in the related folders). 
+* For example, you can define your `application services` and `DTOs` under the **Services** folder.
+
+### How to Run?
+
+Before running the application, you need to create the database and seed the initial data. To do that, you can run the following command in the directory of your project:
+
+```bash
+dotnet run --migrate-database
+```
+
+* This command will create the database and seed the initial data for you. Then you can run the application with any IDE that supports .NET or by running the `dotnet run` CLI command in the directory of your project. The default username is `admin` and the password is `1q2w3E*`.
+
+> While creating a database & applying migrations seem only necessary for relational databases, this project comes even if you choose a NoSQL database provider (like MongoDB). In that case, it still seeds the initial data which is necessary for the application.
+
+### Angular UI 
+
+If you choose `Angular` as the UI framework, the solution will be separated into two folders:
+
+* An `angular` folder that contains the Angular UI application, the client-side code.
+* An `aspnet-core` folder that contains the ASP.NET Core solution (a single project), the server-side code.
+
+The server-side is similar to the solution described in the [Solution Structure](#solution-structure) section above. This project serves the API, so the `Angular` application can consume it.
+
+The client-side application consumes the HTTP APIs as mentioned. You can see the folder structure of the Angular project shown below:
+
+![](../images/single-layer-angular-folder-structure.png)

docs/en/docs-nav.json

@@ -118,6 +118,10 @@
           "text": "Application",
           "path": "Startup-Templates/Application.md"
         },
+        {
+          "text": "Application (Single Layer)",
+          "path": "Startup-Templates/Application-Single-Layer.md"
+        },
         {
           "text": "Module",
           "path": "Startup-Templates/Module.md"