(VB.NET) Microsoft Graph OAuth2 Client Credentials Grant Flow

Demonstrates how to get a Microsoft Graph access token using the Client Credentials Grant Flow.

You can use the OAuth 2.0 client credentials grant specified in RFC 6749, sometimes called two-legged OAuth, to access web-hosted resources by using the identity of an application. This type of grant is commonly used for server-to-server interactions that must run in the background, without immediate interaction with a user. These types of applications are often referred to as daemons or service accounts.

For more information, see https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow

Chilkat .NET Downloads Chilkat .NET Framework Chilkat for .NET Core

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim http As New Chilkat.Http

Dim req As New Chilkat.HttpRequest
req.AddParam("client_secret","CLIENT_SECRET")
req.AddParam("client_id","CLIENT_ID")
' Don't know if the scopes valid for the client credentials grant are different than the scopes for the 3-legged Authorization Code Grant...
req.AddParam("scope","https://graph.microsoft.com/.default")
req.AddParam("grant_type","client_credentials")

' Use your own tenant ID, for example 4d8fdd66-66d1-43b0-ae5c-e31b4b7de5cd
Dim url As String = "https://login.microsoftonline.com/TENANT_ID/oauth2/v2.0/token"
Dim resp As Chilkat.HttpResponse = http.PostUrlEncoded(url,req)
If (http.LastMethodSuccess <> True) Then
    Debug.WriteLine(http.LastErrorText)
    Exit Sub
End If


Dim statusCode As Integer = resp.StatusCode
Debug.WriteLine("Response status code = " & statusCode)

Dim json As New Chilkat.JsonObject
json.Load(resp.BodyStr)


json.EmitCompact = False
Debug.WriteLine(json.Emit())

' Sample successful output:

' {
'   "token_type": "Bearer",
'   "expires_in": 3599,
'   "ext_expires_in": 3599,
'   "access_token": "eyJ0eX...K0jOERg"
' }

If (statusCode = 200) Then
    json.WriteFile("qa_data/tokens/msGraphClientCredentialsToken.json")
    Debug.WriteLine("Success.")
Else
    Debug.WriteLine("Failed.")
End If