How To: Web server in a universal Windows 10 app

Below is a class I wrote to create a simple HTTP server that works in a universal Windows 10 app. Most API's you would use for creation of a web server are not available in these apps, and I could not find any libraries created to help, so I ended up writing it on my own.

Note:

public class HTTPServer : IDisposable
{

    private static HTTPServer instance;

    public static HTTPServer Instance
    {
        get
        {
            if (instance == null)
            {
                instance = new HTTPServer(8000);
            }
            return instance;
        }
    }


    private const uint BufferSize = 8192;

    private readonly StreamSocketListener listener;
    private int port;

    public HTTPServer(int port)
    {
        this.port = port;
        this.listener = new StreamSocketListener();
        this.listener.ConnectionReceived += (s, e) => ProcessRequestAsync(e.Socket);
    }

    public void StartServer()
    {
        #pragma warning disable CS4014
        this.listener.BindServiceNameAsync(port.ToString());
        #pragma warning restore CS4014
    }

    public void Dispose()
    {
        this.listener.Dispose();
    }

    private async void ProcessRequestAsync(StreamSocket socket)
    {
        // this works for text only
        StringBuilder request = new StringBuilder();
        using (IInputStream input = socket.InputStream)
        {
            byte[] data = new byte[BufferSize];
            IBuffer buffer = data.AsBuffer();
            uint dataRead = BufferSize;
            while (dataRead == BufferSize)
            {
                await input.ReadAsync(buffer, BufferSize, InputStreamOptions.Partial);
                request.Append(Encoding.UTF8.GetString(data, 0, data.Length));
                dataRead = buffer.Length;
            }
        }

        using (IOutputStream output = socket.OutputStream)
        {
            HTTPRequest requestInfo = new HTTPRequest(request.ToString());

            if (requestInfo.Method == "GET")
            {
                wait WriteResponseAsync(requestInfo, output);
            }
            else 
            {
                throw new InvalidDataException("HTTP method not supported: "+ requestInfo.Method);
            }
        }
    }

    private async Task WriteResponseAsync(HTTPRequest request, IOutputStream os)
    {
        using (Stream resp = os.AsStreamForWrite())
        {
            bool exists = false;
            if (request.Path.StartsWith("/PUT_URL_HERE"))
            {
                exists = true;

                try
                {
                    StorageFile fs = await StorageFile.GetFileFromPathAsync("FILEPATH");
                    Stream readStream = await fs.OpenStreamForReadAsync();

                    long length = readStream.Length;

                    string header = String.Format("HTTP/1.1 200 OK\r\n" +
                        "Connection: keep-alive\r\n" +
                        "Content-Type: text/html\r\n" +
                        "Content-Length: {1}\r\n" +
                        "\r\n",,
                        length);

                    byte[] headerArray = Encoding.UTF8.GetBytes(header);
                    await resp.WriteAsync(headerArray, 0, headerArray.Length);

                    readStream.Position = start;

                    var bytesToRead = length;

                    byte[] buffer = new byte[BufferSize];
                    int bytesRead = 0;
                    while (bytesToRead > 0 && (bytesRead = await readStream.ReadAsync(buffer, 0, buffer.Length)) > 0)
                    {
                        bytesToRead -= bytesRead;
                        await resp.WriteAsync(buffer, 0, bytesRead);
                    }

                }
                catch (FileNotFoundException)
                {
                    exists = false;
                }
            }

            if (!exists)
            {
                byte[] headerArray = Encoding.UTF8.GetBytes(
                                      "HTTP/1.1 404 Not Found\r\n" +
                                      "Content-Length:0\r\n" +
                                      "Connection: close\r\n\r\n");
                await resp.WriteAsync(headerArray, 0, headerArray.Length);
            }

            await resp.FlushAsync();
        }
    }
}