/// <summary>
/// Function to generate an application token
/// </summary>
/// <returns>Returns the <see cref="AccessTokenInfo"/> token if call is successful, null otherwise </returns>
private AccessTokenInfo GetToken()
{
WebRequest webRequest = WebRequest.Create("https://oxford-speech.cloudapp.net/token/issueToken");
webRequest.ContentType = "application/x-www-form-urlencoded";
webRequest.Method = "POST";
byte[] bytes = Encoding.ASCII.GetBytes(_requestDetails);
webRequest.ContentLength = bytes.Length;
try
{
using (Stream outputStream = webRequest.GetRequestStream())
{
outputStream.Write(bytes, 0, bytes.Length);
}
using (WebResponse webResponse = webRequest.GetResponse())
{
DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(AccessTokenInfo));
AccessTokenInfo token = (AccessTokenInfo)serializer.ReadObject(webResponse.GetResponseStream());
return(token);
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
return(null);
}
}
/// <summary>
/// Function in charge of generating the authentication token
/// </summary>
/// <param name="clientId">Unique id of the current application</param>
/// <param name="clientSecret">Bing Speech API key</param>
/// <returns>Returns true if a token is generated, false otherwise</returns>
public bool GenerateAuthenticationToken(string clientId, string clientSecret)
{
Authentication auth = new Authentication(clientId, clientSecret);
try
{
_token = auth.Token;
if (_token != null)
{
_authorizationToken = $"Bearer {_token.access_token}";
return(true);
}
else
{
RaiseOnError(new AudioErrorEventArgs("Failed to generate authentication token."));
return(false);
}
}
catch (Exception ex)
{
RaiseOnError(new AudioErrorEventArgs($"Failed to generate authentication token - {ex.Message}"));
return(false);
}
}
/// <summary>
/// Constructor - Sets the request details, gets a token and starts a timer for token renewal
/// </summary>
/// <param name="clientId">Id of the current client, should be unique for your application</param>
/// <param name="clientSecret">Bing Speech API key</param>
public Authentication(string clientId, string clientSecret)
{
_requestDetails = string.Format("grant_type=client_credentials&client_id={0}&client_secret={1}&scope={2}",
HttpUtility.UrlEncode(clientId),
HttpUtility.UrlEncode(clientSecret),
HttpUtility.UrlEncode("https://speech.platform.bing.com"));
_token = GetToken();
_tokenRenewer = new Timer(new TimerCallback(OnTokenExpiredCallback),
this,
TimeSpan.FromMinutes(TokenRefreshInterval),
TimeSpan.FromMilliseconds(-1));
}
/// <summary>
/// Function that executes when the timers refresh interval is reached. Will generate a new token
/// </summary>
/// <param name="stateInfo"></param>
private void OnTokenExpiredCallback(object stateInfo)
{
try
{
AccessTokenInfo newAccessToken = GetToken();
_token = newAccessToken;
}
catch (Exception ex)
{
Console.WriteLine(string.Format("Failed renewing access token. Details: {0}", ex.Message));
}
finally
{
_tokenRenewer.Change(TimeSpan.FromMinutes(TokenRefreshInterval), TimeSpan.FromMilliseconds(-1));
}
}
