How to get an OAuth 2.0 access token in VB.NET

Question

How can I request a token by exchanging basic credentials (client id and secret) (OAuth authentication) in VB.NET?

I tried the code below without any success. I get the error saying:

The underlying connection was closed: An unexpected error occurred on a send.

Code

Function test()
    Try
        Dim myHttpWebRequest As HttpWebRequest = CType(WebRequest.Create("https://www.ia.provider.com/access_token"), HttpWebRequest)
        myHttpWebRequest.Method = "POST"
        myHttpWebRequest.ContentType = "application/json"
        myHttpWebRequest.Headers.Add("Authorization", "Basic " & System.Convert.ToBase64String(System.Text.ASCIIEncoding.ASCII.GetBytes("545874a9f5134ed0b54545:333650277fa4d50934c65AAb46Ad123")))

        Dim myHttpWebResponse As HttpWebResponse CType(myHttpWebRequest.GetResponse(), HttpWebResponse)

        Dim myreader As New System.IO.StreamReader(myHttpWebResponse.GetResponseStream)
        Dim myText As String
        myText = myreader.ReadToEnd
        Console.WriteLine(myText)

    Catch e As ArgumentException

        Console.WriteLine(e.Message)
        MsgBox((vbLf & "WebException is thrown. " & vbLf & "Message is:" & e.Message))

    Catch e As WebException
        Console.WriteLine(vbLf & "WebException is thrown. " & vbLf & "Message is :" & e.Message)
        If e.Status = WebExceptionStatus.ProtocolError Then
            Console.WriteLine("Status Code: {0}", CType(e.Response, HttpWebResponse).StatusCode)
            Console.WriteLine("Status Description: {0}", CType(e.Response, HttpWebResponse).StatusDescription)
            Console.WriteLine("Server : {0}", CType(e.Response, HttpWebResponse).Server)
        End If

    Catch e As Exception
        Console.WriteLine("Exception is thrown. Message is:" & e.Message)

    End Try
End Function

Answer 1

The best way is to use RestClient. You can add it to your project from NuGet Package Manager. I've been looking for this answer for a week now. Hopefully it'll help someone in the future. here how to request token:

 Function request_token()

    ServicePointManager.ServerCertificateValidationCallback = AddressOf AcceptAllCertifications
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
    Dim client = New RestClient("https://www.ia.provider.com/access_token")


    Dim request = New RestRequest(Method.POST)
    request.Parameters.Clear()
    request.AddParameter("Authorization", "Basic " & System.Convert.ToBase64String(System.Text.ASCIIEncoding.ASCII.GetBytes("545874a9f5134ed0b54545:333650277fa4d50934c65AAb46Ad123")))
    request.AddParameter("Accept", "application/json")
    request.AddParameter("Content-Type", "application/x-www-form-urlencoded")
    request.AddParameter("Content-Length", "29")
    request.AddParameter("grant_type", "client_credentials")

    Return response.Content.ToString
End Function

Answer 2

Just a minor comment. Mark did not define the response object If someone should be interested in using the example provided by Mark, they should add: Dim response As IRestResponse = request.Execute(request) as a new line above: Return response.Content.ToString .