(Visual Basic 6.0) Get XOAUTH2 Access Token from Google OAuth 2.0 Authorization Server

Obtains an OAUTH2 access token from the Google OAuth 2.0 Authorization Server. This is for Server to server applications using Google API's that need an access token. See https://developers.google.com/accounts/docs/OAuth2ServiceAccount

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

Dim http As New ChilkatHttp

' --------------------------------------------------------------------------------
' For a step-by-step guide for setting up your Google Workspace service account,
' see Setup Google Workspace Account for Sending SMTP GMail from a Service Account
' --------------------------------------------------------------------------------
' Begin by loading your Google service account key (.p12)
Dim cert As New ChilkatCert
Dim success As Long
success = cert.LoadPfxFile("c:/someDirectory/keys/chilkat25-cbd7b42afbd8.p12","notasecret")
If (success <> 1) Then
    Debug.Print cert.LastErrorText
    Exit Sub
End If

' The ISS is your service account email address ending in gserviceaccount.com.
Dim iss As String
iss = "chilkatsvc@chilkat25.iam.gserviceaccount.com"

' The scope is always the following string:
Dim scope As String
scope = "https://mail.google.com/"

' The sub is your company email address
Dim oauth_sub As String
oauth_sub = "bob@yourcompany.com"

' The access token is valid for this number of seconds.
Dim numSec As Long
numSec = 3600

Dim accessToken As String
accessToken = http.G_SvcOauthAccessToken(iss,scope,oauth_sub,numSec,cert)
If (http.LastMethodSuccess <> 1) Then
    Debug.Print http.LastErrorText
    Exit Sub
Else
    Debug.Print "access token: " & accessToken
End If

' The access token allows us to send unlimited emails while it's valid. Once it expires, we must obtain and use a new one.