(DataFlex) 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

Use ChilkatAx-9.5.0-win32.pkg

Procedure Test
    Handle hoFac
    String sJsonKey
    Handle hoGAuth
    Variant vTlsSock
    Handle hoTlsSock
    Boolean iSuccess
    Handle hoMailman
    Variant vEmail
    Handle hoEmail
    String sTemp1
    Boolean bTemp1

    // 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.
    Get Create (RefClass(cComCkFileAccess)) To hoFac
    If (Not(IsComObjectCreated(hoFac))) Begin
        Send CreateComObject of hoFac
    End
    Get ComReadEntireTextFile Of hoFac "qa_data/googleApi/ChilkatTest-ab2ecd52ef98.json" "utf-8" To sJsonKey
    Get ComLastMethodSuccess Of hoFac To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoFac To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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"
    // 	}

    Get Create (RefClass(cComChilkatAuthGoogle)) To hoGAuth
    If (Not(IsComObjectCreated(hoGAuth))) Begin
        Send CreateComObject of hoGAuth
    End
    Set ComJsonKey Of hoGAuth To sJsonKey

    // Choose a scope.
    Set ComScope Of hoGAuth To "https://mail.google.com/"

    // Request an access token that is valid for this many seconds.
    Set ComExpireNumSeconds Of hoGAuth To 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.)
    Set ComSubEmailAddress Of hoGAuth To ""

    // 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.
    Get Create (RefClass(cComChilkatSocket)) To hoTlsSock
    If (Not(IsComObjectCreated(hoTlsSock))) Begin
        Send CreateComObject of hoTlsSock
    End
    Get ComConnect Of hoTlsSock "www.googleapis.com" 443 True 5000 To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoTlsSock To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Send the request to obtain the access token.
    Get pvComObject of hoTlsSock to vTlsSock
    Get ComObtainAccessToken Of hoGAuth vTlsSock To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoGAuth To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Examine the access token:
    Get ComAccessToken Of hoGAuth To sTemp1
    Showln "Access Token: " sTemp1

    // 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.

    // -----------------------------------------------------------------------
    Get Create (RefClass(cComChilkatMailMan)) To hoMailman
    If (Not(IsComObjectCreated(hoMailman))) Begin
        Send CreateComObject of hoMailman
    End

    // Set the properties for the GMail SMTP server:
    Set ComSmtpHost Of hoMailman To "smtp.gmail.com"
    Set ComSmtpPort Of hoMailman To 587
    Set ComStartTLS Of hoMailman To True

    Set ComSmtpUsername Of hoMailman To "YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS"
    Get ComAccessToken Of hoGAuth To sTemp1
    Set ComOAuth2AccessToken Of hoMailman To sTemp1

    // Create a new email object
    Get Create (RefClass(cComChilkatEmail)) To hoEmail
    If (Not(IsComObjectCreated(hoEmail))) Begin
        Send CreateComObject of hoEmail
    End

    Set ComSubject Of hoEmail To "This is a test"
    Set ComBody Of hoEmail To "This is a test"
    Set ComFrom Of hoEmail To "YOUR NAME <YOUR_GOOGLE_APPS_USER_EMAIL_ADDRESS>"
    Get ComAddTo Of hoEmail "Chilkat Admin" "admin@chilkatsoft.com" To iSuccess
    // 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.  
    Get pvComObject of hoEmail to vEmail
    Get ComSendEmail Of hoMailman vEmail To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoMailman To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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).
    Get ComCloseSmtpConnection Of hoMailman To iSuccess
    If (iSuccess <> True) Begin
        Showln "Connection to SMTP server not closed cleanly."
    End

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


End_Procedure