Check if a UserName, Password combination exists in Client Table. Username and Password are passed as parameters. 

A token is passed for authentication. If the authentication fails, or other errors occur, no details which relate to the username/password are returned. The result of the authentication and checking is represented by a TAuthenticate object.  

If the UserName, Password combination exists in a unique record, some details of this record are returned as properties of the returned TAuthenticate object. The TAuthenticate object returned has properties:

• Token = '',
• Status = STATUS_OK = 1,
• StatusMessage = 'Username/Password Combination exists.'
• Identifier = Identifier of user (Client or Staff)
• TokenType = Type of user:
  • '02' a Client (Student, Employee, ...),
  • '03' a Client who is a Staff Member

If there are no matching records, a 'Bad Authenticate' is returned, with:

• Token = '',
• Status = STATUS_NO_RECORDS = -4,
• StatusMessage = 'Invalid Username/Password Combination. '. 

If there are multiple matching records, a 'Bad Authenticate' is returned, with:

• Token = '',
• Status = STATUS_UNKNOWN = 0,
• StatusMessage = 'Username/Password Combination exists in multiple records. '  

[WebMethod(Description = "Checks whether the specified username and password is valid")]
public TAuthenticate DoesUsernamePasswordExist(string sToken, string sUsername, string sPassword);