(Visual FoxPro) Get Access Token using a Pre-Created JSON Web Token

Demonstrates how to get an access token using a pre-created JSON Web Token (JWT).

For more information, see https://developer.abnamro.com/get-started#headingFive

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

LOCAL loPrivkey
LOCAL lnSuccess
LOCAL loJwt
LOCAL loJsonHeader
LOCAL loJsonPayload
LOCAL lnCurDateTime
LOCAL lcJwtStr
LOCAL loHttp
LOCAL loReq
LOCAL loResp
LOCAL loJson

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

* We're going to duplicate this CURL statement:
* curl -X POST https://api-sandbox.abnamro.com/v1/oauth/token \
* -H "Content-Type: application/x-www-form-urlencoded" \
* -H "API-Key: xxxxxx" \
* -d 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&grant_type=client_credentials&client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ4eHh4eHgiLCJleHAiOiIxNDk5OTQ3NjY4IiwiaXNzIjoibWUiLCJhdWQiOiJodHRwczovL2F1dGgtc2FuZGJveC5hYm5hbXJvLmNvbS9vYXV0aC90b2tlbiJ9.jGwHKG_YjgKpR8NPpaLu6nJ97obeP2vcxg6fOWBKdJ0&scope=tikkie'

* Load our pre-creaed private key PEM file.
* Note: Please share your public key along with your app name and developer email id at api.support@nl.abnamro.com. 
* Token generation will not work unless public key is associated with your app.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.PrivateKey')
loPrivkey = CreateObject('Chilkat.PrivateKey')

lnSuccess = loPrivkey.LoadPemFile("qa_data/pem/abnAmroPrivateKey.pem")
IF (lnSuccess = 0) THEN
    ? loPrivkey.LastErrorText
    RELEASE loPrivkey
    CANCEL
ENDIF

* Create the JWT.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Jwt')
loJwt = CreateObject('Chilkat.Jwt')

* Create the header:
* {
*     "typ": "JWT",
*     "alg": "RS256"
* }
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJsonHeader = CreateObject('Chilkat.JsonObject')
loJsonHeader.UpdateString("typ","JWT")
loJsonHeader.UpdateString("alg","RS256")

* Create the payload:
* {
*     "nbf": 1499947668,
*     "exp": 1499948668,
*     "iss": "me",
*     "sub": "anApiKey",
*     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
* }
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJsonPayload = CreateObject('Chilkat.JsonObject')

lnCurDateTime = loJwt.GenNumericDate(0)

* Set the "not process before" timestamp to now.
lnSuccess = loJsonPayload.AddIntAt(-1,"nbf",lnCurDateTime)

* Set the timestamp defining an expiration time (end time) for the token
* to be now + 1 hour (3600 seconds)
lnSuccess = loJsonPayload.AddIntAt(-1,"exp",lnCurDateTime + 3600)

loJsonPayload.UpdateString("iss","me")
loJsonPayload.UpdateString("sub","anApiKey")
loJsonPayload.UpdateString("aud","https://auth-sandbox.abnamro.com/oauth/token")

* Produce the smallest possible JWT:
loJwt.AutoCompact = 1

lcJwtStr = loJwt.CreateJwtPk(loJsonHeader.Emit(),loJsonPayload.Emit(),loPrivkey)
IF (loJwt.LastMethodSuccess <> 1) THEN
    ? loJwt.LastErrorText
    RELEASE loPrivkey
    RELEASE loJwt
    RELEASE loJsonHeader
    RELEASE loJsonPayload
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Http')
loHttp = CreateObject('Chilkat.Http')

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.HttpRequest')
loReq = CreateObject('Chilkat.HttpRequest')
loReq.AddParam("client_assertion_type","urn:ietf:params:oauth:client-assertion-type:jwt-bearer")
loReq.AddParam("grant_type","client_credentials")
loReq.AddParam("client_assertion",lcJwtStr)
loReq.AddParam("scope","tikkie")

loResp = loHttp.PostUrlEncoded("https://api-sandbox.abnamro.com/v1/oauth/token",loReq)
IF (loHttp.LastMethodSuccess = 0) THEN
    ? loHttp.LastErrorText
    RELEASE loPrivkey
    RELEASE loJwt
    RELEASE loJsonHeader
    RELEASE loJsonPayload
    RELEASE loHttp
    RELEASE loReq
    CANCEL
ENDIF

IF (loResp.StatusCode <> 200) THEN
    ? loResp.BodyStr
    RELEASE loResp
    RELEASE loPrivkey
    RELEASE loJwt
    RELEASE loJsonHeader
    RELEASE loJsonPayload
    RELEASE loHttp
    RELEASE loReq
    CANCEL
ENDIF

* Get the JSON result:
* {
*     "access_token": "{your access token}",
*     "expires_in": "{duration of validity in seconds}",
*     "scope": "{scope(s) for which the access token is valid}",
*     "token_type": "{it is always Bearer}"
* }
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.JsonObject')
loJson = CreateObject('Chilkat.JsonObject')
loJson.Load(loResp.BodyStr)
? "access_token: " + loJson.StringOf("access_token")
? "token_type: " + loJson.StringOf("token_type")
? "expires_in: " + loJson.StringOf("expires_in")
? "scope: " + loJson.StringOf("scope")

RELEASE loResp

RELEASE loPrivkey
RELEASE loJwt
RELEASE loJsonHeader
RELEASE loJsonPayload
RELEASE loHttp
RELEASE loReq
RELEASE loJson