DataFlex

Streaming Download Large File to the Local Filesystem

See more Azure Cloud Storage Examples

Downloads a large file in a streaming fashion to the local filesystem. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoRest
    Boolean iBTls
    Integer iPort
    Boolean iBAutoReconnect
    Variant vAzAuth
    Handle hoAzAuth
    Integer iResponseStatusCode
    Variant vBodyStream
    Handle hoBodyStream
    String sErrResponse
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    // Azure File Service Example: Downloads a large file to the local filesystem using a Chilkat stream.
    // See:  https://docs.microsoft.com/en-us/rest/api/storageservices/get-file

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

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End

    // Connect to the Azure Storage Blob Service
    Move True To iBTls
    Move 443 To iPort
    Move True To iBAutoReconnect
    // In this example, the storage account name is "chilkat".
    Get ComConnect Of hoRest "chilkat.file.core.windows.net" iPort iBTls iBAutoReconnect To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Provide Azure Cloud credentials for the REST calls.
    Get Create (RefClass(cComChilkatAuthAzureStorage)) To hoAzAuth
    If (Not(IsComObjectCreated(hoAzAuth))) Begin
        Send CreateComObject of hoAzAuth
    End
    Set ComAccessKey Of hoAzAuth To "AZURE_ACCESS_KEY"
    // The account name used here should match the 1st part of the domain passed in the call to Connect (above).
    Set ComAccount Of hoAzAuth To "chilkat"
    Set ComScheme Of hoAzAuth To "SharedKey"
    Set ComService Of hoAzAuth To "File"
    // This causes the "x-ms-version: 2021-08-06" header to be automatically added.
    Set ComXMsVersion Of hoAzAuth To "2021-08-06"
    Get pvComObject of hoAzAuth to vAzAuth
    Get ComSetAuthAzureStorage Of hoRest vAzAuth To iSuccess

    // Note: The application does not need to explicitly set the following
    // headers: x-ms-date, Authorization.  These headers
    // are automatically set by Chilkat.

    // When streaming a download to the local filesystem or directed elsewhere,
    // the complete HTTP GET operation must be broken into parts.
    // For example, an HTTP GET consists of sending the request, followed by reading the response header,
    // and then finally the response body.  We'll want to read the response header, and then based
    // on the information received (such as success or failure), either read the response body
    // as an error message, or as the file data.

    // Send the HTTP GET request to download the file.
    // The share is named "pip".
    Get ComSendReqNoBody Of hoRest "GET" "/pip/somethingBig.zip" To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Read the response header.
    Get ComReadResponseHeader Of hoRest To iResponseStatusCode
    If (iResponseStatusCode < 0) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Response status code = " iResponseStatusCode

    // We expect a 200 response status if the file data is coming.
    // Otherwise, we'll get a string response body with an error message(or no response body).
    If (iResponseStatusCode = 200) Begin

        Get Create (RefClass(cComChilkatStream)) To hoBodyStream
        If (Not(IsComObjectCreated(hoBodyStream))) Begin
            Send CreateComObject of hoBodyStream
        End

        // The stream's sink will be a file.
        Set ComSinkFile Of hoBodyStream To "qa_output/somethingBig.zip"

        // Read the response body to the stream.  Given that we've
        // set the stream's sink to a file, it will stream directly
        // to the file.
        Get pvComObject of hoBodyStream to vBodyStream
        Get ComReadRespBodyStream Of hoRest vBodyStream True To iSuccess
        If (iSuccess <> True) Begin
            Get ComLastErrorText Of hoRest To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        Showln "Successfully received the large file."

    End
    Else Begin
        Get ComReadRespBodyString Of hoRest To sErrResponse
        Get ComLastMethodSuccess Of hoRest To bTemp1
        If (bTemp1 <> True) Begin
            Get ComLastErrorText Of hoRest To sTemp1
            Showln sTemp1
        End
        Else Begin
            Showln sErrResponse
        End

    End



End_Procedure