(DataFlex) Auto-Refresh O365 Access Token when Sending Email

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Demonstrates how to automatically recover from an expired access token when sending email from smtp.office365.com using OAuth2 authentication. If the server responds with an error indicating that the access token is expired, then we refresh the access token and retry.

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

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoJsonToken
    Boolean iSuccess
    Handle hoMailman
    Variant vEmail
    Handle hoEmail
    Handle hoOauth2
    Variant vSbJson
    Handle hoSbJson
    String sTemp1
    Integer iTemp1

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

    // An Office365 OAuth2 access token must first be obtained prior
    // to running this code.

    // First get our previously obtained OAuth2 access token.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJsonToken
    If (Not(IsComObjectCreated(hoJsonToken))) Begin
        Send CreateComObject of hoJsonToken
    End
    Get ComLoadFile Of hoJsonToken "qa_data/tokens/office365.json" To iSuccess

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

    Set ComSmtpHost Of hoMailman To "smtp.office365.com"
    Set ComSmtpPort Of hoMailman To 587
    Set ComStartTLS Of hoMailman To True

    // Use your Office365 email address for the SmtpUsername.
    Set ComSmtpUsername Of hoMailman To "OFFICE365_EMAIL_ADDRESS"
    Get ComStringOf Of hoJsonToken "access_token" 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 "MY_NAME <OFFICE365_EMAIL_ADDRESS>"
    Get ComAddTo Of hoEmail "John Doe" "somebody@example.com" To iSuccess

    // 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
        Showln "Mail Sent!"
        Procedure_Return
    End

    // If we fall through to here, it means something failed.
    // If we failed because of an invalid or expired access token, we should get this SMTP status code and error message:
    //    response: 535 5.7.3 Authentication unsuccessful [CH2PR19CA0023.namprd19.prod.outlook.com]
    //    status code: 535
    Get ComLastSmtpStatus Of hoMailman To iTemp1
    If (iTemp1 <> 535) Begin
        Get ComLastErrorText Of hoMailman To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // If we get here, it means the SMTP status code equaled 535, which is an authentication failure.
    // Let's refresh the access token, and then retry..

    Get Create (RefClass(cComChilkatOAuth2)) To hoOauth2
    If (Not(IsComObjectCreated(hoOauth2))) Begin
        Send CreateComObject of hoOauth2
    End

    // Update to use your token endpoint.
    // In the Azure Portal, in "App registrations", go to "Endpoints" (located to the right of the "+ New registration" link.)
    //    Find your endpoint for the "OAuth 2.0 token endpoint (v2)"
    //    See Office365 OAuth2 Endpoints

    Set ComTokenEndpoint Of hoOauth2 To "https://login.microsoftonline.com/xxxxxxxxxx-71bf-4ebe-a866-738364321bf2/oauth2/v2.0/token"

    // Replace these with actual values.
    Set ComClientId Of hoOauth2 To "CLIENT_ID"
    Set ComClientSecret Of hoOauth2 To "CLIENT_SECRET"

    // Get the "refresh_token"
    Get ComStringOf Of hoJsonToken "refresh_token" To sTemp1
    Set ComRefreshToken Of hoOauth2 To sTemp1

    // Send the HTTP POST to refresh the access token..
    Get ComRefreshAccessToken Of hoOauth2 To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoOauth2 To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComAccessToken Of hoOauth2 To sTemp1
    Showln "New access token: " sTemp1
    Get ComRefreshToken Of hoOauth2 To sTemp1
    Showln "New refresh token: " sTemp1

    // Update the JSON with the new tokens.
    Get ComAccessToken Of hoOauth2 To sTemp1
    Get ComUpdateString Of hoJsonToken "access_token" sTemp1 To iSuccess
    Get ComRefreshToken Of hoOauth2 To sTemp1
    Get ComUpdateString Of hoJsonToken "refresh_token" sTemp1 To iSuccess

    // Save the new JSON access token response to a file.
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbJson
    If (Not(IsComObjectCreated(hoSbJson))) Begin
        Send CreateComObject of hoSbJson
    End
    Set ComEmitCompact Of hoJsonToken To False
    Get pvComObject of hoSbJson to vSbJson
    Get ComEmitSb Of hoJsonToken vSbJson To iSuccess
    Get ComWriteFile Of hoSbJson "qa_data/tokens/office365.json" "utf-8" False To iSuccess

    Showln "OAuth2 authorization granted!"
    Get ComAccessToken Of hoOauth2 To sTemp1
    Showln "New Access Token = " sTemp1

    // -------------------------------------------------
    // Retry the SMTP send using the refreshed access token.

    Showln "Retrying the send using the refreshed access token."

    Get ComAccessToken Of hoOauth2 To sTemp1
    Set ComOAuth2AccessToken Of hoMailman To sTemp1

    Get pvComObject of hoEmail to vEmail
    Get ComSendEmail Of hoMailman vEmail To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoMailman To sTemp1
        Showln sTemp1
        Procedure_Return
    End

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

    Showln "Email sent!"


End_Procedure