GET Token - C#

using System;            // Note: This can be omitted if Console.WriteLine is not used

namespace Rest_Token_Example
{
    class Program
    {
        static void Main()
        {
            // Set local variables 
            string username = "username";
            string password = "password";
            string getTokenURI = "https://fim.api.ENV.fleetmatics.com/token";

            // Pass variables to create a new TokenGenerator object
            var token = new TokenGenerator(username, password, getTokenURI);

            // Display token string
            Console.WriteLine(token.AuthString);
        }
    }
}

using System;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Text;

namespace Rest_Token_Example
{
    public class TokenGenerator
    {
        private string _authString { get; set; }

        private int _retryCount { get; set; }

        private DateTime _expiredDateTimeUtc { get; set; }

        private string _username { get; set; }

        private string _password { get; set; }

        private string _getTokenUri { get; set; }

        // Public property that returns the token string. The logic contained
        // evaluates if the token is expired when it is accessed. If expired, 
        // a new token is automatically populated, and new token string returned
        public string AuthString 
        {
            get
            {
                if (_expiredDateTimeUtc < DateTime.UtcNow)
                {
                    _authString = GetToken();
                }
                return _authString;
            }
        }

        // Constructor that takes username, password, and enpoint for the Token API
        public TokenGenerator(string username, string password, string uri) 
        {
            // Set private properties
            _getTokenUri = uri;
            _username = username();
            _password = password();
            _authString = GetToken();
        }
						
        private string GetToken() 
        {
            string error;
            do
            {
                // Build authentication and store in variable
                string authenticationString = BuildBasicAuthenticationString(_username, _password);

                // Begin new HttpClient. Use "using" to ensure the resource is released
                using (HttpClient client = new HttpClient())
                {
                    client.DefaultRequestHeaders.Accept.Clear();
                    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("text/plain"));                  // Set expected result type
                    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", authenticationString);   // Pass in stored authentication string to "Basic" Auth header

                    // Begin getting the response from the REST API call, passing in the endpoint to the method
                    using (HttpResponseMessage response = client.GetAsync(_getTokenURI).Result)
                    {
                        // True if HttpStatusCode was in the Successful range (200-299); otherwise false
                        if (response.IsSuccessStatusCode)
                        {
                            Console.WriteLine("Token successfully retrieved");          // Logging
                            _expiredDateTimeUtc = DateTime.UtcNow.AddMinutes(20);       // Set expiry field to current time and add 20 minutes (tokens are no longer valid after 20 mins)
                            _retryCount = 0;                                            // Reset retry counter
                            return response.Content.ReadAsStringAsync().Result;         // Return authentication string
                        }

		        // Only if call has failed (Not 200) will this block be reached.
                        // Increment retry counter and log error.
			_retryCount++;
                        error = string.Format("{0}, {1}", (int)response.StatusCode, response.ReasonPhrase);
                        Console.WriteLine("Http Error {0}. Problem getting token", error);
                    }
                }
            } while (_retryCount < 3);     // If call fails, retry 3 times before throwing Exception

            // Call has faild 3 consecutive times, reset retry counter and throw Exception
            _retryCount = 0;
            throw new Exception(string.Format("Failed 3 retries! Error {0}", error));
        }

        // Converts supplied username and password to byte array which is then converted to
        // a Base64 encoded string and returned
        private static string BuildBasicAuthenticationString(string username, string password)
        {
            var byteArray = Encoding.ASCII.GetBytes(string.Format("{0}:{1}", username, password));
	    return Convert.ToBase64String(byteArray);
        }
    }
}