(Classic ASP) Refresh eBay Application Access Token

This example shows how to get a new eBay REST API access token when the original is close to expiration.

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

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

' If a new access token must be fetched, this example will save the JSON
' containing the token to a file.  The contents of the JSON will look
' like this:

' 	{ 
' 	  "access_token": "v^1.1#i^1#p^1#I^3#r^0# ... Ajp1BQhJDgAA",
' 	  "token_type": "Application Access Token",
' 	  "expires_in": 7200,
' 	  "refresh_token": "N/A",
' 	  "expire_time": "2017-04-16T14:44:20Z"
' 	}

set json = Server.CreateObject("Chilkat_9_5_0.JsonObject")
json.EmitCompact = 0
set dtExpire = Server.CreateObject("Chilkat_9_5_0.CkDateTime")

' First, we'll see if this file already exists from previously
' running this code.
tokenFilePath = "qa_data/tokens/ebay.json"
set fac = Server.CreateObject("Chilkat_9_5_0.FileAccess")
If (fac.FileExists(tokenFilePath) = 1) Then
    success = json.LoadFile(tokenFilePath)

    ' Get the current date/time, then get the expire date/time from the JSON.
    set dtNow = Server.CreateObject("Chilkat_9_5_0.CkDateTime")
    success = dtNow.SetFromCurrentSystemTime()
    ' Add 30 seconds to dtNow so that we refresh if within 30 seconds of the expiration.
    success = dtNow.AddSeconds(30)

    success = dtExpire.SetFromTimestamp(json.StringOf("expire_time"))

    If (dtNow.GetAsUnixTime(0) < dtExpire.GetAsUnixTime(0)) Then
        ' The token has not yet expired.  We can use the access token from this JSOn.
        Response.Write "<pre>" & Server.HTMLEncode( "Non-expired access token: " & json.StringOf("access_token")) & "</pre>"
        Response.End
    End If

End If

' If we fall through to here, then either the existing access token expired,
' or we haven't yet fetched an access token for the first time.
' The remainder of this code snippet fetches the access token and saves
' it to the file.

set http = Server.CreateObject("Chilkat_9_5_0.Http")

' If using the sandbox, the target endpoint will be:
' POST https://api.sandbox.ebay.com/identity/v1/oauth2/token

' If using the production (live) system, the target endpoint will be:
' POST https://api.ebay.com/identity/v1/oauth2/token

' The eBay client_id and client_secret needs to be sent
' in a Basic Authorization  request header, which has this format:
' Authorization: Basic <B64_encoded_oauth_credentials>

' Chilkat takes care of it.  You only need to set the Login = client_id,
' and password = client_secret, and indicate you want "Basic" HTTP Authorization.
http.Login = "EBAY_CLIENT_ID"
http.Password = "EBAY_CLIENT_SECRET"
http.BasicAuth = 1

' Let's do the following POST:

'   HTTP method:   POST
'   URL (Sandbox): https://api.sandbox.ebay.com/identity/v1/oauth2/token
' 
'   HTTP headers:
'     Content-Type = application/x-www-form-urlencoded
'     Authorization = Basic <B64-encoded-oauth-credentials>
' 
'   Request body (wrapped for readability):
'     grant_type=client_credentials&
'     redirect_uri=<RuName-value>&
'     scope=https://api.ebay.com/oauth/api_scope
' 

' Create an HttpRequest object to hold the request params.
set req = Server.CreateObject("Chilkat_9_5_0.HttpRequest")
req.HttpVerb = "POST"
req.AddParam "grant_type","client_credentials"
' (The RuName value that eBay assigns to your application.)
req.AddParam "redirect_uri","EBAY_RUNAME_VALUE"
req.AddParam "scope","https://api.ebay.com/oauth/api_scope"

' (The PostUrlEncoded method automatically sets the Content-Type header equal to "application/x-www-form-urlencoded")
endPoint = "https://api.sandbox.ebay.com/identity/v1/oauth2/token"
' resp is a Chilkat_9_5_0.HttpResponse
Set resp = http.PostUrlEncoded(endPoint,req)
If (http.LastMethodSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( http.LastErrorText) & "</pre>"
    Response.End
End If

' The response is JSON..
success = json.Load(resp.BodyStr)

' If the response status code is not 200, then it failed.
Response.Write "<pre>" & Server.HTMLEncode( "Response status code = " & resp.StatusCode) & "</pre>"
If (resp.StatusCode <> 200) Then
    Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( "Failed.") & "</pre>"
    Response.End
End If

' This application token is only valid for 7200 seconds (2 hours).  We'll want to refresh
' it before it expires.  (There is an online example for that..)
' For now, let's save the JSON to a file for our application to use.

' But before doing that, let's add to the JSON an expiration timestamp
' so we know when to refresh the token.
success = dtExpire.SetFromCurrentSystemTime()
success = dtExpire.AddSeconds(json.IntOf("expires_in"))
success = json.AppendString("expire_time",dtExpire.GetAsTimestamp(0))

' Persist the JSON to a file.
success = fac.WriteEntireTextFile(tokenFilePath,json.Emit(),"utf-8",0)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( fac.LastErrorText) & "</pre>"
    Response.Write "<pre>" & Server.HTMLEncode( "Failed to save eBay Application token to file.") & "</pre>"
    Response.End
End If

' We successfully retrieved a new eBay access token.
accessToken = json.StringOf("access_token")

Response.Write "<pre>" & Server.HTMLEncode( "Use this new access token: " & accessToken) & "</pre>"

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