Classic ASP
Automatically Refresh Token for 401 Unauthorized

Demonstrates how to automatically refresh an access token (without user interaction) when the token expires and a 401 Unauthorized response is received.
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Classic ASP
<html>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<%
success = 0

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

tokenFilePath = "qa_data/tokens/googleCalendar.json"

' Get our current access token.
set jsonToken = Server.CreateObject("Chilkat.JsonObject")
success = jsonToken.LoadFile(tokenFilePath)
If (jsonToken.HasMember("access_token") = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( "No access token found.") & "</pre>"
    Response.End
End If

set http = Server.CreateObject("Chilkat.Http")
http.AuthToken = jsonToken.StringOf("access_token")

jsonResponse = http.QuickGetStr("https://www.googleapis.com/calendar/v3/users/me/calendarList")
If (http.LastMethodSuccess <> 1) Then

    If (http.LastStatus <> 401) Then
        Response.Write "<pre>" & Server.HTMLEncode( http.LastErrorText) & "</pre>"
        Response.Write "<pre>" & Server.HTMLEncode( "----") & "</pre>"
        Response.Write "<pre>" & Server.HTMLEncode( http.LastResponseBody) & "</pre>"
        Response.End
    End If

    ' The access token must've expired. 
    ' Refresh the access token and then retry the request.
    set oauth2 = Server.CreateObject("Chilkat.OAuth2")

    oauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token"

    ' Replace these with actual values.
    oauth2.ClientId = "GOOGLE-CLIENT-ID"
    oauth2.ClientSecret = "GOOGLE-CLIENT-SECRET"

    ' Get the "refresh_token"
    oauth2.RefreshToken = jsonToken.StringOf("refresh_token")

    ' Send the HTTP POST to refresh the access token..
    success = oauth2.RefreshAccessToken()
    If (success <> 1) Then
        Response.Write "<pre>" & Server.HTMLEncode( oauth2.LastErrorText) & "</pre>"
        Response.End
    End If

    ' The response contains a new access token, but we must keep
    ' our existing refresh token for when we need to refresh again in the future.
    success = jsonToken.UpdateString("access_token",oauth2.AccessToken)

    ' Save the new JSON access token response to a file.
    set sbJson = Server.CreateObject("Chilkat.StringBuilder")
    jsonToken.EmitCompact = 0
    success = jsonToken.EmitSb(sbJson)
    success = sbJson.WriteFile(tokenFilePath,"utf-8",0)

    Response.Write "<pre>" & Server.HTMLEncode( "OAuth2 authorization granted!") & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( "New Access Token = " & oauth2.AccessToken) & "</pre>"

    ' re-try the original request.
    http.AuthToken = oauth2.AccessToken
    jsonResponse = http.QuickGetStr("https://www.googleapis.com/calendar/v3/users/me/calendarList")
    If (http.LastMethodSuccess <> 1) Then
        Response.Write "<pre>" & Server.HTMLEncode( http.LastErrorText) & "</pre>"
        Response.End
    End If

End If

Response.Write "<pre>" & Server.HTMLEncode( jsonResponse) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "-----------------------------") & "</pre>"

%>
</body>
</html>