(DataFlex) Get Google API Access Token using JSON Private Key using NIST Time Server Date/Time

Demonstrates how to get a Google API access token using a JSON service account private key, using the NIST time server date/time rather than the local system date/time.

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

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoSocket
    Integer iMaxWaitMs
    Boolean iUseTls
    Boolean iSuccess
    Boolean iBigEndian
    Handle hoDt
    Boolean iBLocalTime
    Handle hoFac
    String sJsonKey
    Handle hoGAuth
    Integer iUnixTime
    Variant vTlsSock
    Handle hoTlsSock
    Boolean iSuccess
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

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

    // First, let's get the current date/time from time-c.nist.gov
    Get Create (RefClass(cComChilkatSocket)) To hoSocket
    If (Not(IsComObjectCreated(hoSocket))) Begin
        Send CreateComObject of hoSocket
    End

    // Connect to an NIST time server and read the current date/time
    Move 8000 To iMaxWaitMs
    Move False To iUseTls
    Get ComConnect Of hoSocket "time-c.nist.gov" 37 iUseTls iMaxWaitMs To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // The time server will send a big-endian 32-bit integer representing
    // the number of seconds since since 00:00 (midnight) 1 January 1900 GMT.
    // The ReceiveInt32 method will receive a 4-byte integer, but returns
    // True or False to indicate success.  If successful, the integer
    // is obtained via the ReceivedInt property.
    Move True To iBigEndian
    Get ComReceiveInt32 Of hoSocket iBigEndian To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComCkDateTime)) To hoDt
    If (Not(IsComObjectCreated(hoDt))) Begin
        Send CreateComObject of hoDt
    End
    Get ComReceivedInt Of hoSocket To iTemp1
    Get ComSetFromNtpTime Of hoDt iTemp1 To iSuccess

    // Show the current local date/time
    Move True To iBLocalTime
    Get ComGetAsRfc822 Of hoDt iBLocalTime To sTemp1
    Showln "Current local date/time: " sTemp1

    Move 10 To iMaxWaitMs
    Get ComClose Of hoSocket iMaxWaitMs To iSuccess

    // ------------------------------------------------------------------------
    // OK, we have the current date/time.  We'll use it to set the IAT property
    // in the code below.

    // 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://www.googleapis.com/auth/cloud-platform"

    // 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 ""

    // ------------------------------------------------------------------------
    // Set the IAT using the date/time from the NIST time server.
    Get ComGetAsUnixTime Of hoDt False To iUnixTime
    Showln "unixTime = " iUnixTime
    Set ComIat Of hoGAuth To iUnixTime

    // 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


End_Procedure