Xojo Plugin

Streaming Download Large File to the Local Filesystem

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

Dim success As Boolean
success = False

// 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.

Dim rest As New Chilkat.Rest

// Connect to the Azure Storage Blob Service
Dim bTls As Boolean
bTls = True
Dim port As Int32
port = 443
Dim bAutoReconnect As Boolean
bAutoReconnect = True
// In this example, the storage account name is "chilkat".
success = rest.Connect("chilkat.file.core.windows.net",port,bTls,bAutoReconnect)
If (success <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

// Provide Azure Cloud credentials for the REST calls.
Dim azAuth As New Chilkat.AuthAzureStorage
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).
azAuth.Account = "chilkat"
azAuth.Scheme = "SharedKey"
azAuth.Service = "File"
// This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion = "2021-08-06"
success = rest.SetAuthAzureStorage(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".
success = rest.SendReqNoBody("GET","/pip/somethingBig.zip")
If (success <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

// Read the response header.
Dim responseStatusCode As Int32
responseStatusCode = rest.ReadResponseHeader()
If (responseStatusCode < 0) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

System.DebugLog("Response status code = " + Str(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 (responseStatusCode = 200) Then

    Dim bodyStream As New Chilkat.Stream

    // The stream's sink will be a file.
    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.
    success = rest.ReadRespBodyStream(bodyStream,True)
    If (success <> True) Then
        System.DebugLog(rest.LastErrorText)
        Return
    End If

    System.DebugLog("Successfully received the large file.")

Else
    Dim errResponse As String
    errResponse = rest.ReadRespBodyString()
    If (rest.LastMethodSuccess <> True) Then
        System.DebugLog(rest.LastErrorText)
    Else
        System.DebugLog(errResponse)
    End If

End If