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  Application Notes
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This application, WebApiLect13 contains a pair of Web Api controllers:
  - FilesController     (demonstrated in Lecture 13)
  - FileItemsController (earlier version demonstrated in Lecture 12)
and two console client applications:
  - CoreConsoleClient that builds as a dll to be run by the dotnet CLI  (demo in Lecture 13)
  - FWConsoleClient that builds as an exe to be run from the cmd prompt (demo in Lecture 13)

The Lecture 12 application used an in-memory database.  This application uses SQLExpress.
The move from in-memory to SQL db required:
1. changing to services.AddDbContext<FileContext>(opt =>
                 opt.UseSqlServer(
                 Configuration.GetConnectionString("DefaultConnection")));
   in Startup.ConfigureServices
2. Adding a connection string in appsettings.json.  I copied a connection string from another
   application, then changed the database name and the GUID to a new value.  I got the new
   value from Tools > CreateGUID > RegistryFormat.  That puts the GUID on the clipboard.  I
   just pasted that over the GUID in the original connection string.
3. Open Tools > Nuget package manager > Package Manager Console, then add-migration [Initial],
   and update-database.
That's all that was required.

Next, I added the FilesController.cs
1. Right click on the project and select Add > New Item > Web > Api Controller Class.
2. Filled in Controller methods:
   - FilesController(IHostingEnvironment hostingEnvironment)
     The hostingEnvironment is injected by the runtime and provides access to wwwroot path.
   - [HttpGet] public IEnumerable<string> Get() to get listing of files in wwwroot\FileStorage
   - [HttpGet("{id}")] public async Task<IActionResult> Download(int id) to download file
   - [HttpPost] public async Task<IActionResult> Upload() to upload file
That's everything about the FilesController demonstrated in class.

Finally, I added an Asp.Net Core console project, CoreConsoleClient, that builds a dll hosted by
the dotnet CLI, and an Asp.Net Framework console project, FWConsoleClient, that builds an exe that
executes in a cmd prompt.  The GetFileList requires extracting filenames from the Json stored in
the HttpResponse Message body.  To do that you need to import the NewtonSoft package using the
Nuget Package Manager > Manage Nuget Packages for Solution.
1. Both have identical code that includes client methods:
   - CoreConsoleClient(string url)
   - public async Task<HttpResponseMessage> SendFile(string fileSpec) to upload a file
   - public async Task<IEnumerable<string>> GetFileList() to get listing of files in wwwroot\FileStorage
   - public async Task<HttpResponseMessage> GetFile(int id) to download file with index id
   - public async Task<HttpResponseMessage> DeleteFile(int id) to delete file with index id
     The server [HttpDelete("{id}")] public void Delete(int id) has not been implemented
That's everything that was demonstrated in class.

One final note: The return types of the Web Api Controller methods are automatically serialized into
Json in the HttpResponse message body.  The file list gets extracted by methods provided by NewtonSoft
package.  All the other responses are just displayed as text on the console.