Classic ASP

Refresh a Dynamics CRM OAuth2 Access Token

Demonstrates how to refresh an expiring Dynamics CRM access token using the refresh token. endpoint.

(If a REST API call fails with a 401 unauthorized error, an application can auto-recover by refreshing the access token, and then re-send the request using the new token.)

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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

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

' We previously obtained an access token and saved the JSON to a file using this example:
' Get Dynamics CRM OAuth2 Access Token

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

set json = Server.CreateObject("Chilkat.JsonObject")
success = json.LoadFile("qa_data/tokens/dynamicsCrm.json")
If (success <> 1) Then
    Response.End
End If

' The contents of the JSON look like this:
' {
'   "token_type": "Bearer",
'   "scope": "user_impersonation",
'   "expires_in": "3599",
'   "ext_expires_in": "0",
'   "expires_on": "1524783438",
'   "not_before": "1524779538",
'   "resource": "https://mydomain.api.crm.dynamics.com",
'   "access_token": "...",
'   "refresh_token": "...",
'   "id_token": "..."
' }

' The "expires_on" value is a Unix time.
set dtExpire = Server.CreateObject("Chilkat.CkDateTime")
success = dtExpire.SetFromUnixTime(0,json.IntOf("expires_on"))

' If this date/time expires within 10 minutes of the current system time, refresh the token.

' OK, we need to refresh the access token by sending a POST...
' 

set req = Server.CreateObject("Chilkat.HttpRequest")
req.AddParam "grant_type","refresh_token"
req.AddParam "redirect_uri","http://localhost:3017/"
req.AddParam "client_id","DYNAMICS-CRM-CLIENT-ID"
req.AddParam "client_secret","DYNAMICS-CRM-SECRET-KEY"
req.AddParam "refresh_token",json.StringOf("refresh_token")
req.AddParam "resource","https://mydynamicsdomain.api.crm.dynamics.com"

set http = Server.CreateObject("Chilkat.Http")

req.HttpVerb = "POST"
req.ContentType = "application/x-www-form-urlencoded"

set resp = Server.CreateObject("Chilkat.HttpResponse")
success = http.HttpReq("https://login.microsoftonline.com/DYNAMICS-ENDPOINT-GUID/oauth2/token",req,resp)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( http.LastErrorText) & "</pre>"
    Response.End
End If

' Load the JSON response.
success = json.Load(resp.BodyStr)
json.EmitCompact = 0

' Show the JSON response.
Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>"

Response.Write "<pre>" & Server.HTMLEncode( "Response status code: " & resp.StatusCode) & "</pre>"

' If the response status code is not 200, then it's an error.
If (resp.StatusCode <> 200) Then
    Response.End
End If

' 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") <> 1) Then
    success = dtExpire.SetFromCurrentSystemTime()
    success = dtExpire.AddSeconds(json.IntOf("expires_in"))
    success = json.AppendString("expires_on",dtExpire.GetAsUnixTimeStr(0))
End If

' Save the refreshed access token JSON to a file for future requests.
set fac = Server.CreateObject("Chilkat.FileAccess")
success = fac.WriteEntireTextFile("qa_data/tokens/dynamicsCrm.json",json.Emit(),"utf-8",0)

%>
</body>
</html>