Complete the BLOB Storing File System Provider

docs/en/Blob-Storing-File-System.md

@@ -1,3 +1,59 @@
 # BLOB Storing File System Provider
 
-TODO
+File System Storage Provider is used to store BLOBs in the local file system as standard files inside a folder.
+
+> Read the BLOB Storing document to understand how to use the BLOB storing system. This document only covers how to configure containers to use the file system.
+
+## Installation
+
+Use the ABP CLI to add [Volo.Abp.BlobStoring.FileSystem](https://www.nuget.org/packages/Volo.Abp.BlobStoring.FileSystem) NuGet package to your project:
+
+* Install the [ABP CLI](https://docs.abp.io/en/abp/latest/CLI) if you haven't installed before.
+* Open a command line (terminal) in the directory of the `.csproj` file you want to add the `Volo.Abp.BlobStoring.FileSystem` package.
+* Run `abp add-package Volo.Abp.BlobStoring.FileSystem` command.
+
+If you want to do it manually, install the [Volo.Abp.BlobStoring](https://www.nuget.org/packages/Volo.Abp.BlobStoring) NuGet package to your project and add `[DependsOn(typeof(AbpBlobStoringModule))]` to the [ABP module](Module-Development-Basics.md) class inside your project.
+
+## Configuration
+
+Configuration is done in the `ConfigureServices` method of your [module](Module-Development-Basics.md) class, as explained in the [BLOB Storing document](Blob-Storing.md).
+
+**Example: Configure to use the File System storage provider by default**
+
+````csharp
+Configure<AbpBlobStoringOptions>(options =>
+{
+    options.Containers.ConfigureDefault(container =>
+    {
+        container.UseFileSystem(fileSystem =>
+        {
+            fileSystem.BasePath = "C:\\my-files";
+        });
+    });
+});
+````
+
+`UseFileSystem` extension method is used to set the File System Provider for a container and configure the file system options.
+
+> See the [BLOB Storing document](Blob-Storing.md) to learn how to configure this provider for a specific container.
+
+### Options
+
+* **BasePath** (string): The base folder path to store BLOBs. It is required to set this option.
+* **AppendContainerNameToBasePath** (bool; default: `true`): Indicates whether to create a folder with the container name inside the base folder. If you store multiple containers in the same `BaseFolder`, leave this as `true`. Otherwise, you can set it to `false` if you don't like an unnecessarily deeper folder hierarchy.
+
+## File Path Calculation
+
+File System Provider organizes BLOB files inside folders and implements some conventions. The full path of a BLOB file is determined by the following rules by default:
+
+* It starts with the `BasePath` configured as shown above.
+* Appends `host` folder if [current tenant](Multi-Tenancy.md) is `null` (or multi-tenancy is disabled for the container - see the [BLOB Storing document](Blob-Storing.md) to learn how to disable multi-tenancy for a container).
+* Appends `tenants/<tenant-id>` folder if current tenant is not `null`.
+* Appends the container's name if `AppendContainerNameToBasePath` is `true`. If container name contains `/`, this will result with nested folders.
+* Appends the BLOB name. If the BLOB name contains `/` it creates folders. If the BLOB name contains `.` it will have a file extension.
+
+## Extending the File System BLOB Provider
+
+* `FileSystemBlobProvider` is the main service that implements the File System storage. You can inherit from this class and [override](Customizing-Application-Modules-Overriding-Services.md) methods to customize it.
+
+* The `IBlobFilePathCalculator` service is used to calculate the file paths. Default implementation is the `DefaultBlobFilePathCalculator`. You can replace/override it if you want to customize the file path calculation.