HTTP Server cpprest POST handle a filestream

I found on google this code that basically upload a file to a HTTP Server in Async mode via cpprest. If i have sufficiently enough (i'm newbye to PPL and cpprest and read lots of web pages on msdn) i create a task that open an ifstream from out.txt and then create another task that make a HTTP request with PUT method with file stream as body as input from previous task.

If it's correct... from Server side: 1)how to manage PUT method with a filestream? 2)i need to open a file with the same name of input file,is it possible to extract this info from the body HTTP PUT or i need to put this info inside "out.txt"?

    // Upload a file to an HTTP server.
    pplx::task<void> UploadFileToHttpServerAsync()
    {
         using concurrency::streams::file_stream;
         using concurrency::streams::basic_istream;

    // To run this example, you must have a file named out.txt in the                                                                                                                                           current folder.


    // Open stream to file.
        wstring filePath = L"out.txt";
        return file_stream<unsigned char>::open_istream(L"filePath").then([](pplx::task<basic_istream<unsigned char>> previousTask)
        {
            try
            { 
                auto fileStream = previousTask.get();
                http_client client(L"http://localhost:80");
                return client.request(methods::PUT, L"filePath", fileStream).then([fileStream](pplx::task<http_response> previousTask)
                {
                    fileStream.close();

                    std::wostringstream ss;
                    try
                    {
                        auto response = previousTask.get();
                        ss << L"Server returned returned status code " << response.status_code() << L"." << std::endl;
                    }
                    catch (const http_exception& e)
                    {
                        ss << e.what() << std::endl;
                    }
                    std::wcout << ss.str();
                });
         }
         catch (const std::system_error& e)
         {
             std::wostringstream ss;
             ss << e.what() << std::endl;
             std::wcout << ss.str();

             // Return an empty task.
             return pplx::task_from_result();
         }
});