(Visual FoxPro) OAuth2 for a GMail using a JSON Service Account Key

Demonstrates how get an OAuth2 access token for GMail (Google Service Account) using a JSON private key.

After the access token is obtained, it may be used to send email. When the access token expires, a new access token needs to be obtained (using this same procedure).

Note: This is for OAuth2 using Google Service account keys.

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

LOCAL loFac
LOCAL lcJsonKey
LOCAL loGAuth
LOCAL loTlsSock
LOCAL lnSuccess
LOCAL loMailman
LOCAL loEmail

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

* First load the JSON key into a string.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.FileAccess')
loFac = CreateObject('Chilkat.FileAccess')
lcJsonKey = loFac.ReadEntireTextFile("qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json","utf-8")
IF (loFac.LastMethodSuccess <> 1) THEN
    ? loFac.LastErrorText
    RELEASE loFac
    CANCEL
ENDIF

* A JSON private key should look like this:

* 	{
* 	  "type": "service_account",
* 	  "project_id": "chilkattest-1350",
* 	  "private_key_id": "fa2e36ee26986eab628b59868af8bec1d1c64c38",
* 	  "private_key": "-----BEGIN PRIVATE KEY-----\nMIIEvgIjFa...28N64N2n1E4FYzBZjSdy\n-----END PRIVATE KEY-----\n",
* 	  "client_email": "598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a@developer.gserviceaccount.com",
* 	  "client_id": "598922945226-00rb0ppfg0snd9jo7bhvd4v17jtj2d3a.apps.googleusercontent.com",
* 	  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
* 	  "token_uri": "https://accounts.google.com/o/oauth2/token",
* 	  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
* 	  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/598922945226-00rb0ppfg0sndajo6bhvd4v17jtj2d3a%40developer.gserviceaccount.com"
* 	}

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.AuthGoogle')
loGAuth = CreateObject('Chilkat.AuthGoogle')
loGAuth.JsonKey = lcJsonKey

* Choose a scope.
loGAuth.Scope = "https://mail.google.com/"

* Request an access token that is valid for this many seconds.
loGAuth.ExpireNumSeconds = 3600

* If the application is requesting delegated access:
* The email address of the user for which the application is requesting delegated access,
* then set the email address here. (Otherwise leave it empty.)
loGAuth.SubEmailAddress = ""

* Connect to www.googleapis.com using TLS (TLS 1.2 is the default.)
* The Chilkat socket object is used so that the connection can be established
* through proxies or an SSH tunnel if desired.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Socket')
loTlsSock = CreateObject('Chilkat.Socket')
lnSuccess = loTlsSock.Connect("www.googleapis.com",443,1,5000)
IF (lnSuccess <> 1) THEN
    ? loTlsSock.LastErrorText
    RELEASE loFac
    RELEASE loGAuth
    RELEASE loTlsSock
    CANCEL
ENDIF

* Send the request to obtain the access token.
lnSuccess = loGAuth.ObtainAccessToken(loTlsSock)
IF (lnSuccess <> 1) THEN
    ? loGAuth.LastErrorText
    RELEASE loFac
    RELEASE loGAuth
    RELEASE loTlsSock
    CANCEL
ENDIF

* Examine the access token:
? "Access Token: " + loGAuth.AccessToken

* Now that we have the access token, it may be used to send email
* while it remains valid.  Once the access token expires, a new access token 
* should be obtained using the same code as above.

* -----------------------------------------------------------------------
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.MailMan')
loMailman = CreateObject('Chilkat.MailMan')

* Set the properties for the GMail SMTP server:
loMailman.SmtpHost = "smtp.gmail.com"
loMailman.SmtpPort = 587
loMailman.StartTLS = 1

loMailman.SmtpUsername = "YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS"
loMailman.OAuth2AccessToken = loGAuth.AccessToken

* Create a new email object
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Email')
loEmail = CreateObject('Chilkat.Email')

loEmail.Subject = "This is a test"
loEmail.Body = "This is a test"
loEmail.From = "YOUR NAME <YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS>"
lnSuccess = loEmail.AddTo("Chilkat Admin","admin@chilkatsoft.com")
* To add more recipients, call AddTo, AddCC, or AddBcc once per recipient.

* Call SendEmail to connect to the SMTP server and send.
* The connection (i.e. session) to the SMTP server remains
* open so that subsequent SendEmail calls may use the
* same connection.  
lnSuccess = loMailman.SendEmail(loEmail)
IF (lnSuccess <> 1) THEN
    ? loMailman.LastErrorText
    RELEASE loFac
    RELEASE loGAuth
    RELEASE loTlsSock
    RELEASE loMailman
    RELEASE loEmail
    CANCEL
ENDIF

* You may close the connection here.  If the connection is kept open, 
* the next call to mailman.SendEmail will continue using the already-established connection
* (and automatically re-connect if needed).
lnSuccess = loMailman.CloseSmtpConnection()
IF (lnSuccess <> 1) THEN
    ? "Connection to SMTP server not closed cleanly."
ENDIF

? "Email Sent via GMail using an OAuth2 Service Account Key."

RELEASE loFac
RELEASE loGAuth
RELEASE loTlsSock
RELEASE loMailman
RELEASE loEmail