VB.NET

Refresh Expiring OAuth2 Access Token for Azure Registered App

See more OAuth2 Examples

Shows how to renew an Azure App's access token using the refresh token when it's near expiration. VB.NET

Dim success As Boolean = False

' We previously obtained an access token and saved the JSON to a file using this example:
' Get OAuth2 Access Token for Azure Registered App

' This example will examine the JSON and expiration date, and if near expiration will
' refresh the access token.

Dim json As New Chilkat.JsonObject
success = json.LoadFile("qa_data/tokens/_myAzureApp.json")
If (success <> True) Then
    Debug.WriteLine("Failed to load the access token.")
    Exit Sub
End If


' The contents of the JSON look like this:
' {
'   "token_type": "Bearer",
'   "scope": "User.Read Mail.ReadWrite Mail.Send",
'   "expires_in": 3600,
'   "ext_expires_in": 0,
'   "access_token": "EwBAA8l6B...",
'   "refresh_token": "MCRMdbe6Cd...",
'   "id_token": "eyJ0eXAiOiJ...",
'   "expires_on": "1494112119"
' }

' The "expires_on" value is a Unix time.
Dim dtExpire As New Chilkat.CkDateTime
dtExpire.SetFromUnixTime(False,json.IntOf("expires_on"))

' If this date/time expires within 10 minutes of the current system time, refresh the token.
If (dtExpire.ExpiresWithin(10,"minutes") <> True) Then
    Debug.WriteLine("No need to refresh, the access token won't expire within the next 10 minutes.")
    Exit Sub
End If


' OK, we need to refresh the access token..
Dim oauth2 As New Chilkat.OAuth2

' Note: The endpoint depends on the Azure App Registration.
' See How to Choose the Correct Endpoints for your Azure App Registration
oauth2.TokenEndpoint = "https://login.microsoftonline.com/common/oauth2/v2.0/token"

' Use your client ID.
oauth2.ClientId = "CLIENT_ID"

' Get the existing refresh token.
oauth2.RefreshToken = json.StringOf("refresh_token")

' Send the HTTP POST to refresh the access token.
success = oauth2.RefreshAccessToken()
If (success = False) Then
    Debug.WriteLine(oauth2.LastErrorText)
    Exit Sub
End If


Debug.WriteLine("OAuth2 authorization granted!")
Debug.WriteLine("Access Token = " & oauth2.AccessToken)

' Get the full JSON response:
json.Load(oauth2.AccessTokenResponse)
json.EmitCompact = False

' If an "expires_on" member does not exist, then add the JSON member by
' getting the current system date/time and adding the "expires_in" seconds.
' This way we'll know when the token expires.
If (json.HasMember("expires_on") <> True) Then
    dtExpire.SetFromCurrentSystemTime()
    dtExpire.AddSeconds(json.IntOf("expires_in"))
    json.AppendString("expires_on",dtExpire.GetAsUnixTimeStr(False))
End If


Debug.WriteLine(json.Emit())

' Save the new access token JSON to a file for future requests.
Dim fac As New Chilkat.FileAccess
fac.WriteEntireTextFile("qa_data/tokens/_myAzureApp.json",json.Emit(),"utf-8",False)