PowerBuilder

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. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Rest
integer li_BTls
integer li_Port
integer li_BAutoReconnect
oleobject loo_AzAuth
integer li_ResponseStatusCode
oleobject loo_BodyStream
string ls_ErrResponse

li_Success = 0

// 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.

loo_Rest = create oleobject
li_rc = loo_Rest.ConnectToNewObject("Chilkat.Rest")
if li_rc < 0 then
    destroy loo_Rest
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// Connect to the Azure Storage Blob Service
li_BTls = 1
li_Port = 443
li_BAutoReconnect = 1
// In this example, the storage account name is "chilkat".
li_Success = loo_Rest.Connect("chilkat.file.core.windows.net",li_Port,li_BTls,li_BAutoReconnect)
if li_Success <> 1 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Rest
    return
end if

// Provide Azure Cloud credentials for the REST calls.
loo_AzAuth = create oleobject
li_rc = loo_AzAuth.ConnectToNewObject("Chilkat.AuthAzureStorage")

loo_AzAuth.AccessKey = "AZURE_ACCESS_KEY"
// The account name used here should match the 1st part of the domain passed in the call to Connect (above).
loo_AzAuth.Account = "chilkat"
loo_AzAuth.Scheme = "SharedKey"
loo_AzAuth.Service = "File"
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
loo_AzAuth.XMsVersion = "2021-08-06"
li_Success = loo_Rest.SetAuthAzureStorage(loo_AzAuth)

// 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".
li_Success = loo_Rest.SendReqNoBody("GET","/pip/somethingBig.zip")
if li_Success <> 1 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Rest
    destroy loo_AzAuth
    return
end if

// Read the response header.
li_ResponseStatusCode = loo_Rest.ReadResponseHeader()
if li_ResponseStatusCode < 0 then
    Write-Debug loo_Rest.LastErrorText
    destroy loo_Rest
    destroy loo_AzAuth
    return
end if

Write-Debug "Response status code = " + string(li_ResponseStatusCode)

// 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 li_ResponseStatusCode = 200 then

    loo_BodyStream = create oleobject
    li_rc = loo_BodyStream.ConnectToNewObject("Chilkat.Stream")

    // The stream's sink will be a file.
    loo_BodyStream.SinkFile = "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.
    li_Success = loo_Rest.ReadRespBodyStream(loo_BodyStream,1)
    if li_Success <> 1 then
        Write-Debug loo_Rest.LastErrorText
        destroy loo_Rest
        destroy loo_AzAuth
        destroy loo_BodyStream
        return
    end if

    Write-Debug "Successfully received the large file."

else
    ls_ErrResponse = loo_Rest.ReadRespBodyString()
    if loo_Rest.LastMethodSuccess <> 1 then
        Write-Debug loo_Rest.LastErrorText
    else
        Write-Debug ls_ErrResponse
    end if

end if



destroy loo_Rest
destroy loo_AzAuth
destroy loo_BodyStream