B4X

Refresh Expiring OAuth2 Access Token for Azure Registered App

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Shows how to renew an Azure App's access token using the refresh token when it's near expiration. B4X

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 ChilkatJsonObject
json.Initialize
success = json.LoadFile("qa_data/tokens/_myAzureApp.json")
If success <> True Then
    Log("Failed to load the access token.")
    Return
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 ChilkatDateTime
dtExpire.Initialize
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
    Log("No need to refresh, the access token won't expire within the next 10 minutes.")
    Return
End If


'  OK, we need to refresh the access token..
Dim oauth2 As ChilkatOAuth2
oauth2.Initialize("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
    Log(oauth2.LastErrorText)
    Return
End If


Log("OAuth2 authorization granted!")
Log("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


Log(json.Emit)

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